By Steve Francis
If you ride or have ever ridden a motorcycle, then you have experienced the feeling of total freedom. A motorcycle of today is so easy to ride all you really have to do is keep your balance and hang on. Well, it may not be quite that simple. There are a few variables that come into play such as weather, road conditions, and other motorists. Of the three just mentioned, which do you think is the most important? If you said other motorists, you are correct.
According to the National Highway Safety Administration nearly half of all motorcyle fatalities were caused by a crash with another vehicle. Half of those involved alcohol and a little over a third involved speeding. Now if someone pulls out in front of you, there's not much you can do about that. The alcohol and speeding are well within a person's control, so that is on that person and nobody else.
The term "motorcycle safety" is overused. I prefer personal safety. After all, I can replace the motorcycle. I can't replace myself or my passenger quite that easily. With that thought, I offer the following. Nothing new, just a few things that could save a life.
Be very careful when entering an intersection and be especially alert for someone turning left in front of you. Always be prepared to take evasive action. Be aware when riding with the sun at your back. Even with your headlight on, don't assume the approaching motorist can see you. Be careful when taking curves because we all know what a little loose gravel can do. Don't drink and ride a motorcycle.
These are just a few reminders that never hurt to be mentioned from time to time. Oh yes. There is something else. Always wear protective clothing and a helmet. It's amazing what they can do for you.
Now for the real surprise. Bet you didn't see this coming. It just so happens that RitzyShopper.com has the finest motorcycle parts and accessories you will find anywhere on the planet. Motorcycle helmets that are Dot or Snell rated. Motorcycle boots, jackets, gloves and ATV gear are available now. Anything you need from tires to casual wear is waiting for you here. Be a RitzyShopper and remember it's not motorcycle safety that counts. It's personal safety!!
Steve Francis writes articles primarily for http://www.RitzyShopper.com It is enjoyable work as I get to write about different topics related to products marketed by top quality merchants. This particular article dealt with motorcycle safety. Be a http://www.RitzyShopper.com by visiting our merchants and getting your proper motorcycle and ATV protective gear today!
Thursday, May 31, 2007
Monday, May 28, 2007
The Women's No-B.S. Beginning Guide to Motorcycles - Part One
By Janet Green
I've said it before: women learn differently than men. My personal feeling is that we're more cautious, more studious, and less "just do it." We're also pretty supportive of each other in general, but when serious questions arise about how, exactly, one gets started riding motorcycles, that can lead to inadvertant sugar-coating and very vague answers given in such a round-about way as to be completely meaningless. So here is an attempt to bust through all the nicey-nice... you can still get that elsewhere... and just answer some questions directly. We'll take it in small chunks because, well, it's just easier to write it that way.
The first question for a new rider always comes from that place in the woman's heart that wants to be practical, yet take a risk, yet not have any nasty surprises as she's getting started down a new road. The question is, "What do I need to get started?"
It's tempting to try to pass this question off with something really vague and diplomatic like, "That's different for every person." But since this isn't the nicey-nice Beginner's Guide, I'll take a stand and say you can actually boil it down to a short list of five things you need to get started riding. Here they are:
You need a practice bike. Borrow or buy a small-cc brike from someone who can show you the proper start-up procedure for that bike. (They're not going to teach you to ride, but it would be helpful if they could show you how to start the bike.) Don't forget insurance.
You need some safety gear. A DOT-approved helmet, leather or armored textile jacket, and sturdy riding boots that cover your ankles and have solid gripping soles are necessities. Some type of gloves, at least the fingerless style that cover your palms, are also a good idea.
You need instruction. You can learn from a trusted, experienced friend or spouse, but you run the risk of picking up bad riding habits. The Motorcycle Safety Foundation (MSF) offers courses at venues across the country, and some insurance companies offer a discount if you train with MSF.
You need a practice area. Just because you pass your MSF doesn't mean you'll feel comfortable enough to cruise out on the highway immediately. A large parking lot, preferably empty, is ideal.
Finally, you need support, or at least encouragement, preferably from an experienced rider. Tackling a new skill is always easier if you have someone to cheer you on or even help you learn and practice. At a minimum, you need a person who will speak encouraging words and who won't constantly berate you for trying or blather on about the horrible accident their friend's cousin was in.
So that's it, the bare necessities if you want to learn to ride. Don't skimp on 'em!
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
I've said it before: women learn differently than men. My personal feeling is that we're more cautious, more studious, and less "just do it." We're also pretty supportive of each other in general, but when serious questions arise about how, exactly, one gets started riding motorcycles, that can lead to inadvertant sugar-coating and very vague answers given in such a round-about way as to be completely meaningless. So here is an attempt to bust through all the nicey-nice... you can still get that elsewhere... and just answer some questions directly. We'll take it in small chunks because, well, it's just easier to write it that way.
The first question for a new rider always comes from that place in the woman's heart that wants to be practical, yet take a risk, yet not have any nasty surprises as she's getting started down a new road. The question is, "What do I need to get started?"
It's tempting to try to pass this question off with something really vague and diplomatic like, "That's different for every person." But since this isn't the nicey-nice Beginner's Guide, I'll take a stand and say you can actually boil it down to a short list of five things you need to get started riding. Here they are:
You need a practice bike. Borrow or buy a small-cc brike from someone who can show you the proper start-up procedure for that bike. (They're not going to teach you to ride, but it would be helpful if they could show you how to start the bike.) Don't forget insurance.
You need some safety gear. A DOT-approved helmet, leather or armored textile jacket, and sturdy riding boots that cover your ankles and have solid gripping soles are necessities. Some type of gloves, at least the fingerless style that cover your palms, are also a good idea.
You need instruction. You can learn from a trusted, experienced friend or spouse, but you run the risk of picking up bad riding habits. The Motorcycle Safety Foundation (MSF) offers courses at venues across the country, and some insurance companies offer a discount if you train with MSF.
You need a practice area. Just because you pass your MSF doesn't mean you'll feel comfortable enough to cruise out on the highway immediately. A large parking lot, preferably empty, is ideal.
Finally, you need support, or at least encouragement, preferably from an experienced rider. Tackling a new skill is always easier if you have someone to cheer you on or even help you learn and practice. At a minimum, you need a person who will speak encouraging words and who won't constantly berate you for trying or blather on about the horrible accident their friend's cousin was in.
So that's it, the bare necessities if you want to learn to ride. Don't skimp on 'em!
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
Friday, May 25, 2007
The Women's No-B.S. Beginning Guide to Motorcycles - Part Two
By Janet Green
The next question new riders often ask is, "What kind of bike should I get?" This question has a zillion possible correct answers, depending on your comfort-level with riding at the time you're ready to shop, the type of bike you want to own (sport bike? cruiser?), your budget, your personal tastes, brand appeal, etc. For simplicity's sake, though, I'll take a stab and answer the question directly assuming you want a cruiser that's similar to what you used in your MSF course.
The three major manufacturer bikes I would recommend for absolute beginners are:
The Yamaha Virago 250 - a great-looking, easy to handle V-twin.
The Honda Rebel 250 - classic-styled, chain-driven 250
The Kawasaki 125 - single-cylinder five-speed, air-cooled commuter bike
If you're confident in your abilities but not ready for the heavyweight cruisers, there are a few more choices. These are my favorites, in no particular order:
The Yamaha VStar 650 - Classic, custom, or Silverado styling; an awesome middleweight cruiser you may never outgrow.
The Honda VLX or VLX Deluxe - Low to the ground, four-speed 600.
The Honda 750's: Aero & Spirit - five-speed bikes with forward controls
Harley Davidson Sportster 883, Standard or Low - If your heart's set on Harley, the 883 has the HD looks, sound and agility. Of the majors, only the Honda Aero has a lower seat height.
Kawasaki Vulcan - sizes range from 500 to the 900 Classic.
Suzuki Boulevard C50 and S50 bikes - five speeds, forward controls, higher seat height
For a more thorough comparison of these and other bikes, try the BikerChickNews Short Rider Spreadsheet. Although it was intended to be a round-up of cruiser models for shorter riders, it also serves well as a guide to mid-weight bikes from various manufacturers. It's by no means complete, but it might be a good place to start.
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
The next question new riders often ask is, "What kind of bike should I get?" This question has a zillion possible correct answers, depending on your comfort-level with riding at the time you're ready to shop, the type of bike you want to own (sport bike? cruiser?), your budget, your personal tastes, brand appeal, etc. For simplicity's sake, though, I'll take a stab and answer the question directly assuming you want a cruiser that's similar to what you used in your MSF course.
The three major manufacturer bikes I would recommend for absolute beginners are:
The Yamaha Virago 250 - a great-looking, easy to handle V-twin.
The Honda Rebel 250 - classic-styled, chain-driven 250
The Kawasaki 125 - single-cylinder five-speed, air-cooled commuter bike
If you're confident in your abilities but not ready for the heavyweight cruisers, there are a few more choices. These are my favorites, in no particular order:
The Yamaha VStar 650 - Classic, custom, or Silverado styling; an awesome middleweight cruiser you may never outgrow.
The Honda VLX or VLX Deluxe - Low to the ground, four-speed 600.
The Honda 750's: Aero & Spirit - five-speed bikes with forward controls
Harley Davidson Sportster 883, Standard or Low - If your heart's set on Harley, the 883 has the HD looks, sound and agility. Of the majors, only the Honda Aero has a lower seat height.
Kawasaki Vulcan - sizes range from 500 to the 900 Classic.
Suzuki Boulevard C50 and S50 bikes - five speeds, forward controls, higher seat height
For a more thorough comparison of these and other bikes, try the BikerChickNews Short Rider Spreadsheet. Although it was intended to be a round-up of cruiser models for shorter riders, it also serves well as a guide to mid-weight bikes from various manufacturers. It's by no means complete, but it might be a good place to start.
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
Tuesday, May 22, 2007
Motorcycle Tire Basics
By Ray Taylor
This is the first in a series of articles exploring motorcycle tire basics and various basic dynamic characteristics of the handling behavior of motorcycles. Overall this is a very complex subject and needs a good level of mathematics and physics to properly understand what's happening. However, in these articles I'll try and explain the basics with the absolute minimum of mathematics, but where this is unavoidable I'll not go beyond simple trigonometry. For those that are unhappy with any mathematics at all, don't worry, just skip those parts and the rest should still prove useful. I'll try and illustrate the mechanics with many sketches and graphs.
It seems incredible that just two small contact patches of rubber, can support our machines and manage to deliver large amounts of power to the road, whilst at the same time supporting cornering forces at least as much as the weight of the bike and rider. As such the tires exert perhaps the single most important influence over general handling characteristics, so it seems appropriate to study their characteristics before the other various aspects of chassis design. When Newton first expounded to the world his theories of mechanics, no doubt he had on his mind, things other than the interaction of motorcycle tires with the road surface. Never-the-less his suppositions are equally valid for this situation. In particular his third law states, "For every force there is an equal and opposite force to resist it." or to put it another way "Action and reaction are equal and opposite."
Relating this to tire action, means that when the tire is pushing on the road then the road is pushing back equally hard on the tire. This applies equally well regardless of whether we are looking at supporting the weight of the bike or resisting cornering, braking or driving loads. What this particular law of Newton does not concern itself with, is which force is the originating one nor indeed does it matter for many purposes of analysis. However, as a guide to the understanding of some physical systems it is often useful to mentally separate the action from the reaction. The forces that occur between the ground and the tires determine so much the behaviour of our machines, but they are so often taken for granted. tires really perform such a multitude of different tasks and their apparent simplicity hides the degree of engineering sophistication that goes into their design and fabrication. Initially pneumatic tires were fitted to improve comfort and reduce loads on the wheels. Even with modern suspension systems it is still the tires that provide the first line of defence for absorbing road shocks. To explore carcass construction, tread compound and tread pattern in great detail is beyond the scope of this book. Rather we are concerned here with some basic principles and their effects on handling characteristics.
Weight Support
The most obvious function of the tire is to support the weight of the machine, whether upright or leaning over in a corner. However, the actual mechanism by which the air pressure and tire passes the wheel load to the road is often misunderstood. Consider fig. 1, this sketch represents a slice through the bottom of a rim and tire of unit thickness with an inflation pressure of P. The left hand side shows the wheel unloaded and the right hand side shows it supporting the weight F. When loaded the tire is compressed vertically and the width increases as shown, perhaps surprisingly the internal air pressure does not change significantly with load, the internal volume is little changed. At the widest section (X1) of the unloaded tire the internal half width is W1, and so the force normal to this section due to the internal pressure is simply 2.P.W1 . This force acts upwards towards the wheel rim, but as the pressure and tire width are evenly distributed around the circumference the overall effect is completely balanced. This force also has to be resisted by an equal tension (T) in the tire carcass.
The loaded tire has a half width of W2 at it's widest section (X2) and so the normal force is 2.P.W2 . Therefore, the extra force over this section, when loaded, is 2.P.(W2 � W1) but as the tire is only widened over a small portion of the bottom part of the circumference, this force supports the load F. The above describes how the inflation pressure and tire width increase produce forces to oppose the vertical wheel loading, but does not completely explain the detail of the mechanism by which these forces are transferred to the rim. The bead of a fitted tire is an interference fit over the bead seat of the wheel rim, which puts this area into compression, the in-line component of the side-wall tension due to the inflation pressure reduces this compression somewhat. This component is shown as F1 on the unloaded half of F1 = T.cos(U1). The greater angle U2 of the side-wall when loaded means that the in-line component of the tension is reduced, thereby also restoring some of the rim to tire bead compression. This only happens in the lower part of the tire circumference, where the widening takes place. So there is a nett increase in the compressive force on the lower rim acting upward, this supports the bike weight. The nett force is the difference between the unloaded and loaded in-line forces,
F = T.(cos( U1) -cos(U2))
The left hand side shows half of an inflated but unloaded tire, a tension (T) is created in the carcass by the internal pressure. To the right, the compressed and widened shape of the loaded tire is shown.
Suspension Action
In performing this function the pneumatic tire is the first object that feels any road shocks and so acts as the most important element in the machine's suspension system. To the extent that, whilst uncomfortable, it would be quite feasible to ride a bike around the roads, at reasonable speeds with no other form of bump absorption. In fact rear suspension was not at all common until the 1940s or 50s. Whereas, regardless of the sophistication of the conventional suspension system, it would be quite impractical to use wheels without pneumatic tires, or some other form of tire that allowed considerable bump deflection. The loads fed into the wheels without such tires would be enormous at all but slow speeds, and continual wheel failure would be the norm. A few figures will illustrate what I mean:--Assume that a bike, with a normal size front wheel, hits a 25 mm, sharp edged bump at 190 km/h. This not a large bump. With no tire the wheel would then be subject to an average vertical acceleration of approximately 1000 G. (the peak value would be higher than this). This means than if the wheel and brake assembly had a mass of 25 kg. then the average point load on the rim would be 245 kN. or about 25 tons. What wheel could stand that? If the wheel was shod with a normal tire, then this would have at ground level, a spring rate, to a sharp edge, of approx. 17-35 N/mm. The maximum force then transmitted to the wheel for a 25 mm. step would be about 425-875 N. i.e. less than four thousandths of the previous figure, and this load would be more evenly spread around the rim. Without the tire the shock loads passed back to the sprung part of the bike would be much higher too. The vertical wheel velocity would be very much greater, and so the bump damping forces, which depend on wheel velocity, would be tremendous. These high forces would be transmitted directly back to bike and rider. The following five charts show some results of a computer simulation of accelerations and displacements on a typical road motorcycle, and illustrate the tire's significance to comfort and road holding. The bike is traveling at 100 km/h. and the front wheel hits a 0.025 metre high step at 0.1 seconds. Note that the time scales vary from graph to graph. Three cases are considered:
� With typical vertical tire stiffness and typical suspension springing and damping.
� With identical tire properties but with a suspension spring rate of 100 X that of the previous.
� With tire stiffness 100 X the above and with normal suspension springing.
So basically we are considering a typical case, another case with almost no suspension springing and the final case is with a virtually rigid tire. Structural loading, comfort and roadholding would all be adversely affected without the initial cushioning of the tire. Note that the above charts are not all to the same time scale, this is simply to better illustrate the appropriate points.
This shows the vertical displacement of the front wheel. There is little difference between the maximum displacements for the two cases with a normal tire, for a small step the front tire absorbs most of the shock. However, in the case of a very stiff tire, the wheel movement is increased by a factor of about 10 times. It is obvious that the tire leaves the ground in this case and the landing bounces can be seen after 0.5 seconds.
These curves show the vertical movement of the C of G of the bike and rider. As in Fig 1 it is clear that the stiff tire causes much higher bike movements, to the obvious detriment of comfort.
Demonstrating the different accelerations transmitted to the bike and rider, these curves show the vertical accelerations at the C of G. Both of the stiffer tire or stiffer suspension cases show similar values of about 5 or 6 times that of the normal case, but the shape of the two curves is quite different. With the stiff suspension there is little damping and we can see that it takes a few cycles to settle down. The second bump at around 0.155 seconds is when the rear wheel hits the step, this rear wheel response is not shown on the other graphs for clarity.
Front wheel vertical acceleration for the two cases with a normal tire. The early part is similar for the two cases, the suspension has little effect here, it is tire deflection that is the most important for this height of step. As in Fig 5 the lack of suspension damping allows the tire to bounce for a few cycles before settling down.
As in these curves are of the wheel acceleration, the values of the normal case are overwhelmed by the stiff tire case, with a peak value of close to 600 G compared with nearly 80 G normally. Again note the effects of the landing bounces after 0.5 seconds. This high acceleration would cause very high structural loading.
As the tire is so good at removing most of the road shocks, right at the point of application, perhaps it would be worth while to consider designing it to absorb even more and eliminate the need for other suspension. Unfortunately we would run into other problems. We have all seen large construction machinery bouncing down the road on their balloon tires, sometimes this gets so violent that the wheels actually leave the ground. A pneumatic tire acts just like an air spring, and the rubber acts as a damper when it flexes, but when the tire is made bigger the springing effect overwhelms the damping and we then get the uncontrolled bouncing. So there are practical restraints to the amount of cushioning that can be built into a tire for any given application.
Effects of Tire Pressure
Obviously, the springing characteristics mentioned above are largely affected by the tire inflation pressure, but there are other influences also. Carcass material and construction and the properties and tread pattern of the outer layer of rubber all have an effect on both the springing properties and the area in contact with the ground (contact patch). Under and over inflation both allow the tire to assume non-optimum cross-sectional shapes, additionally the inflation pressure exerts an influence over the lateral flexibility of a tire and this is a property of the utmost importance to motorcycle stability. Manufacturers' recommendations should always be adhered to.
The influence of tire pressure on the vertical stiffness of an inflated tire, when loaded on a flat surface. These curves are from actual measured data. Note that the spring rate is close to linear over the full range of loading and varies from 14 kgf/mm. at 1.9 bar pressure to 19 kgf/mm. at 2.9 bar. The effective spring rate when the tire is loaded against a sharp edge, such as a brick, is considerably lower than this, and is more non-linear due to the changing shape of the contact area as the tire "wraps" around the object.
This spring rate acts in series with the suspension springs and is an important part of the overall suspension system. An interesting property of rubber is that when compressed and released it doesn't usually return exactly to it's original position, this is known as hysteresis. This effect is shown only for the 1.9 bar. case, the curve drawn during the loading phase is not followed during the unloading phase. The area between these two curves represents a loss of energy which results in tire heating and also acts as a form of suspension damping. In this particular case the energy lost over one loading and unloading cycle is approximately 10% of the total stored energy in the compressed tire, and is a significant parameter controlling tire bounce.
Vertical stiffness of a standard road tire against a flat surface at different inflation pressures. This data is from an Avon Azaro Sport II 170/60 ZR17. The upward arrows indicate the compression of the tire and the 2nd line with the downward arrow (shown only at 1.9 bar for clarity) shows the behaviour of the tire when the load is released. The shaded area between the two lines represents a loss of energy called hysteresis. This acts as a source of suspension damping and also heats the tire. (From data supplied by Avon tires.)
Lateral stiffness of the same tire shown in fig. 9. The vertical load was constant at 355 kgf. and the wheel was kept vertical. As expected the tire is somewhat stiffer with the higher inflation pressure but loses grip or saturates at the lower lateral load of 460 kgf. compared to 490 kgf. at the lower pressure. (From data supplied by Avon tires.)
Contact Area
The tire must ultimately give it's support to the bike through a small area of rubber in contact with the ground, and so "contact patch area = vertical force � average contact patch surface pressure". This applies under ALL conditions.
The contact patch surface pressure is NOT however, the same as the inflation pressure, as is sometimes claimed. They are related but there are at least four factors which modify the relationship. Carcass stiffness, carcass shape, surface rubber depth and softness, and road surface compliance. If we have an extremely high carcass stiffness then inflation pressure will have a reduced influence. Let's look at this in a little more detail and see why:
If a tire was made just like an inner tube, that is from quite thin rubber and with little stiffness unless inflated, then the internal air pressure would be the only means to support the bike's weight. In this case the contact patch pressure would be equal to that of the internal air pressure. For an air pressure of 2 bar and a vertical load of 1.0 kN. Then the contact area would be 5003 sq.mm. If we now increased the air pressure to say 3 bar the area would fall to 3335 sq.mm.
Let's now imagine that we substitute a rigid steel tubular hoop for our rim and tire, the area in contact with the ground will be quite small. If we now inflate the hoop with some air pressure, it doesn't take much imagination to see that, unlike the inner tube, this internal pressure will have a negligible effect on the external area of contact. Obviously, a tire is not exactly like the steel hoop, nor the inner tube, but this does show that the carcass rigidity can reduce the contact surface area as calculated purely from inflation pressure alone.
I did 2 sets of tests. For the first I kept the tire inflation pressure constant at 2.4 bar and varied the tire load between 178 and 1210 N. (allowing for the weight of the glass and wooden beams). Secondly, I keep a constant load of 1210 N. and tried varying the inflation pressure between 2.4 to 1 bar. Even with a generous allowance for experimental error the effects are clear. The graphs show that the results appeared to fit reasonably well to a smooth line, there wasn't much scatter.
Point (1) on the curve with constant inflation pressure, shows how the actual contact patch pressure is lower (just over half) than the inflation pressure, or in other words the contact area is greater. This is due to the rubber surface compliance, thus this is more important at low vertical loads, whereas carcass stiffness became more important as the load rose as shown by points (3) to (6) where the actual contact pressure is higher than the air pressure, i.e. reduced area of contact.
Measurement setup. Various weights were placed on the end of a beam, which also loaded the tire via a thick plate of glass. The beam was arranged to apply the load to the tire with a 4:1 leverage. So a 25 kgf. weight would load the tire with 100 kgf. By tracing over the glass the contact area was determined.
The top plot shows the measured contact patch pressure at various wheel loads for a constant inflation pressure of 2.4 bar. The lower curves show the contact pressure at various inflation pressures for a fixed load of 1210 N. The numbers at the data points correspond with the contact area tracings in the previous sketch. The plain line on each plot shows the case of the contact patch pressure being equal to the inflation pressure.
The carcass stiffness helps to support the machine as the air pressure is reduced, the contact patch pressure being considerably higher than the inflation pressure. It looks as though the two lines will cross at an air pressure of about 3.5 bar. (although this was not tested by measurement), at which point the surface rubber compression will assume the greatest importance. This is as per the steel hoop analogy above.
We can easily see the two separate effects of surface compliance and carcass stiffness and how the relative importance of these varies with load and/or inflation pressure.
These tests were only done with one particular tire, other types will show different detail results but the overall effects should follow a similar pattern.
Area Under Cornering
Does cornering affect tire contact area? Let's assume a horizontal surface and lateral acceleration of 1G. Under these conditions the bike/rider CoG will be on a line at 45� to the horizontal and passing through the contact patch. There will a resultant force acting along this line through the contact patch of 1.4 times the supported weight.
This force is the resultant of the supported weight and the cornering force, which have the same magnitude, in this example of a 45� lean. The force normal to the surface is simply that due to the supported weight and does NOT vary with cornering force. The cornering force is reacted by the horizontal frictional force generated by the tire/road surface and this frictional force is "allowed" by virtue of the normal force.
Therefore, to a first approximation cornering force will NOT affect the tire contact area, and in fact this case could be approximated to, if we were just considering the inner tube without a real world tire. However in reality, the lateral force will cause some additional tire distortion to take place at the road/tire interface and depending on the tire characteristics, mentioned above, the contact area may well change.
Another aspect to this is of course the tire cross-sectional profile. The old Dunlop triangular racing tire, for example, was designed to put more rubber on the road when leant over, so even without tire distortion the contact patch area increased, simply by virtue of the lean angle.
by Ray Taylor
http://www.CarsNet.com/motorcycle
Ray Taylor owns the real world San Diego Auto Swap and also owns http://www.CarsNet.com and http://www.SanDiegoAutoSwap.com
This is the first in a series of articles exploring motorcycle tire basics and various basic dynamic characteristics of the handling behavior of motorcycles. Overall this is a very complex subject and needs a good level of mathematics and physics to properly understand what's happening. However, in these articles I'll try and explain the basics with the absolute minimum of mathematics, but where this is unavoidable I'll not go beyond simple trigonometry. For those that are unhappy with any mathematics at all, don't worry, just skip those parts and the rest should still prove useful. I'll try and illustrate the mechanics with many sketches and graphs.
It seems incredible that just two small contact patches of rubber, can support our machines and manage to deliver large amounts of power to the road, whilst at the same time supporting cornering forces at least as much as the weight of the bike and rider. As such the tires exert perhaps the single most important influence over general handling characteristics, so it seems appropriate to study their characteristics before the other various aspects of chassis design. When Newton first expounded to the world his theories of mechanics, no doubt he had on his mind, things other than the interaction of motorcycle tires with the road surface. Never-the-less his suppositions are equally valid for this situation. In particular his third law states, "For every force there is an equal and opposite force to resist it." or to put it another way "Action and reaction are equal and opposite."
Relating this to tire action, means that when the tire is pushing on the road then the road is pushing back equally hard on the tire. This applies equally well regardless of whether we are looking at supporting the weight of the bike or resisting cornering, braking or driving loads. What this particular law of Newton does not concern itself with, is which force is the originating one nor indeed does it matter for many purposes of analysis. However, as a guide to the understanding of some physical systems it is often useful to mentally separate the action from the reaction. The forces that occur between the ground and the tires determine so much the behaviour of our machines, but they are so often taken for granted. tires really perform such a multitude of different tasks and their apparent simplicity hides the degree of engineering sophistication that goes into their design and fabrication. Initially pneumatic tires were fitted to improve comfort and reduce loads on the wheels. Even with modern suspension systems it is still the tires that provide the first line of defence for absorbing road shocks. To explore carcass construction, tread compound and tread pattern in great detail is beyond the scope of this book. Rather we are concerned here with some basic principles and their effects on handling characteristics.
Weight Support
The most obvious function of the tire is to support the weight of the machine, whether upright or leaning over in a corner. However, the actual mechanism by which the air pressure and tire passes the wheel load to the road is often misunderstood. Consider fig. 1, this sketch represents a slice through the bottom of a rim and tire of unit thickness with an inflation pressure of P. The left hand side shows the wheel unloaded and the right hand side shows it supporting the weight F. When loaded the tire is compressed vertically and the width increases as shown, perhaps surprisingly the internal air pressure does not change significantly with load, the internal volume is little changed. At the widest section (X1) of the unloaded tire the internal half width is W1, and so the force normal to this section due to the internal pressure is simply 2.P.W1 . This force acts upwards towards the wheel rim, but as the pressure and tire width are evenly distributed around the circumference the overall effect is completely balanced. This force also has to be resisted by an equal tension (T) in the tire carcass.
The loaded tire has a half width of W2 at it's widest section (X2) and so the normal force is 2.P.W2 . Therefore, the extra force over this section, when loaded, is 2.P.(W2 � W1) but as the tire is only widened over a small portion of the bottom part of the circumference, this force supports the load F. The above describes how the inflation pressure and tire width increase produce forces to oppose the vertical wheel loading, but does not completely explain the detail of the mechanism by which these forces are transferred to the rim. The bead of a fitted tire is an interference fit over the bead seat of the wheel rim, which puts this area into compression, the in-line component of the side-wall tension due to the inflation pressure reduces this compression somewhat. This component is shown as F1 on the unloaded half of F1 = T.cos(U1). The greater angle U2 of the side-wall when loaded means that the in-line component of the tension is reduced, thereby also restoring some of the rim to tire bead compression. This only happens in the lower part of the tire circumference, where the widening takes place. So there is a nett increase in the compressive force on the lower rim acting upward, this supports the bike weight. The nett force is the difference between the unloaded and loaded in-line forces,
F = T.(cos( U1) -cos(U2))
The left hand side shows half of an inflated but unloaded tire, a tension (T) is created in the carcass by the internal pressure. To the right, the compressed and widened shape of the loaded tire is shown.
Suspension Action
In performing this function the pneumatic tire is the first object that feels any road shocks and so acts as the most important element in the machine's suspension system. To the extent that, whilst uncomfortable, it would be quite feasible to ride a bike around the roads, at reasonable speeds with no other form of bump absorption. In fact rear suspension was not at all common until the 1940s or 50s. Whereas, regardless of the sophistication of the conventional suspension system, it would be quite impractical to use wheels without pneumatic tires, or some other form of tire that allowed considerable bump deflection. The loads fed into the wheels without such tires would be enormous at all but slow speeds, and continual wheel failure would be the norm. A few figures will illustrate what I mean:--Assume that a bike, with a normal size front wheel, hits a 25 mm, sharp edged bump at 190 km/h. This not a large bump. With no tire the wheel would then be subject to an average vertical acceleration of approximately 1000 G. (the peak value would be higher than this). This means than if the wheel and brake assembly had a mass of 25 kg. then the average point load on the rim would be 245 kN. or about 25 tons. What wheel could stand that? If the wheel was shod with a normal tire, then this would have at ground level, a spring rate, to a sharp edge, of approx. 17-35 N/mm. The maximum force then transmitted to the wheel for a 25 mm. step would be about 425-875 N. i.e. less than four thousandths of the previous figure, and this load would be more evenly spread around the rim. Without the tire the shock loads passed back to the sprung part of the bike would be much higher too. The vertical wheel velocity would be very much greater, and so the bump damping forces, which depend on wheel velocity, would be tremendous. These high forces would be transmitted directly back to bike and rider. The following five charts show some results of a computer simulation of accelerations and displacements on a typical road motorcycle, and illustrate the tire's significance to comfort and road holding. The bike is traveling at 100 km/h. and the front wheel hits a 0.025 metre high step at 0.1 seconds. Note that the time scales vary from graph to graph. Three cases are considered:
� With typical vertical tire stiffness and typical suspension springing and damping.
� With identical tire properties but with a suspension spring rate of 100 X that of the previous.
� With tire stiffness 100 X the above and with normal suspension springing.
So basically we are considering a typical case, another case with almost no suspension springing and the final case is with a virtually rigid tire. Structural loading, comfort and roadholding would all be adversely affected without the initial cushioning of the tire. Note that the above charts are not all to the same time scale, this is simply to better illustrate the appropriate points.
This shows the vertical displacement of the front wheel. There is little difference between the maximum displacements for the two cases with a normal tire, for a small step the front tire absorbs most of the shock. However, in the case of a very stiff tire, the wheel movement is increased by a factor of about 10 times. It is obvious that the tire leaves the ground in this case and the landing bounces can be seen after 0.5 seconds.
These curves show the vertical movement of the C of G of the bike and rider. As in Fig 1 it is clear that the stiff tire causes much higher bike movements, to the obvious detriment of comfort.
Demonstrating the different accelerations transmitted to the bike and rider, these curves show the vertical accelerations at the C of G. Both of the stiffer tire or stiffer suspension cases show similar values of about 5 or 6 times that of the normal case, but the shape of the two curves is quite different. With the stiff suspension there is little damping and we can see that it takes a few cycles to settle down. The second bump at around 0.155 seconds is when the rear wheel hits the step, this rear wheel response is not shown on the other graphs for clarity.
Front wheel vertical acceleration for the two cases with a normal tire. The early part is similar for the two cases, the suspension has little effect here, it is tire deflection that is the most important for this height of step. As in Fig 5 the lack of suspension damping allows the tire to bounce for a few cycles before settling down.
As in these curves are of the wheel acceleration, the values of the normal case are overwhelmed by the stiff tire case, with a peak value of close to 600 G compared with nearly 80 G normally. Again note the effects of the landing bounces after 0.5 seconds. This high acceleration would cause very high structural loading.
As the tire is so good at removing most of the road shocks, right at the point of application, perhaps it would be worth while to consider designing it to absorb even more and eliminate the need for other suspension. Unfortunately we would run into other problems. We have all seen large construction machinery bouncing down the road on their balloon tires, sometimes this gets so violent that the wheels actually leave the ground. A pneumatic tire acts just like an air spring, and the rubber acts as a damper when it flexes, but when the tire is made bigger the springing effect overwhelms the damping and we then get the uncontrolled bouncing. So there are practical restraints to the amount of cushioning that can be built into a tire for any given application.
Effects of Tire Pressure
Obviously, the springing characteristics mentioned above are largely affected by the tire inflation pressure, but there are other influences also. Carcass material and construction and the properties and tread pattern of the outer layer of rubber all have an effect on both the springing properties and the area in contact with the ground (contact patch). Under and over inflation both allow the tire to assume non-optimum cross-sectional shapes, additionally the inflation pressure exerts an influence over the lateral flexibility of a tire and this is a property of the utmost importance to motorcycle stability. Manufacturers' recommendations should always be adhered to.
The influence of tire pressure on the vertical stiffness of an inflated tire, when loaded on a flat surface. These curves are from actual measured data. Note that the spring rate is close to linear over the full range of loading and varies from 14 kgf/mm. at 1.9 bar pressure to 19 kgf/mm. at 2.9 bar. The effective spring rate when the tire is loaded against a sharp edge, such as a brick, is considerably lower than this, and is more non-linear due to the changing shape of the contact area as the tire "wraps" around the object.
This spring rate acts in series with the suspension springs and is an important part of the overall suspension system. An interesting property of rubber is that when compressed and released it doesn't usually return exactly to it's original position, this is known as hysteresis. This effect is shown only for the 1.9 bar. case, the curve drawn during the loading phase is not followed during the unloading phase. The area between these two curves represents a loss of energy which results in tire heating and also acts as a form of suspension damping. In this particular case the energy lost over one loading and unloading cycle is approximately 10% of the total stored energy in the compressed tire, and is a significant parameter controlling tire bounce.
Vertical stiffness of a standard road tire against a flat surface at different inflation pressures. This data is from an Avon Azaro Sport II 170/60 ZR17. The upward arrows indicate the compression of the tire and the 2nd line with the downward arrow (shown only at 1.9 bar for clarity) shows the behaviour of the tire when the load is released. The shaded area between the two lines represents a loss of energy called hysteresis. This acts as a source of suspension damping and also heats the tire. (From data supplied by Avon tires.)
Lateral stiffness of the same tire shown in fig. 9. The vertical load was constant at 355 kgf. and the wheel was kept vertical. As expected the tire is somewhat stiffer with the higher inflation pressure but loses grip or saturates at the lower lateral load of 460 kgf. compared to 490 kgf. at the lower pressure. (From data supplied by Avon tires.)
Contact Area
The tire must ultimately give it's support to the bike through a small area of rubber in contact with the ground, and so "contact patch area = vertical force � average contact patch surface pressure". This applies under ALL conditions.
The contact patch surface pressure is NOT however, the same as the inflation pressure, as is sometimes claimed. They are related but there are at least four factors which modify the relationship. Carcass stiffness, carcass shape, surface rubber depth and softness, and road surface compliance. If we have an extremely high carcass stiffness then inflation pressure will have a reduced influence. Let's look at this in a little more detail and see why:
If a tire was made just like an inner tube, that is from quite thin rubber and with little stiffness unless inflated, then the internal air pressure would be the only means to support the bike's weight. In this case the contact patch pressure would be equal to that of the internal air pressure. For an air pressure of 2 bar and a vertical load of 1.0 kN. Then the contact area would be 5003 sq.mm. If we now increased the air pressure to say 3 bar the area would fall to 3335 sq.mm.
Let's now imagine that we substitute a rigid steel tubular hoop for our rim and tire, the area in contact with the ground will be quite small. If we now inflate the hoop with some air pressure, it doesn't take much imagination to see that, unlike the inner tube, this internal pressure will have a negligible effect on the external area of contact. Obviously, a tire is not exactly like the steel hoop, nor the inner tube, but this does show that the carcass rigidity can reduce the contact surface area as calculated purely from inflation pressure alone.
I did 2 sets of tests. For the first I kept the tire inflation pressure constant at 2.4 bar and varied the tire load between 178 and 1210 N. (allowing for the weight of the glass and wooden beams). Secondly, I keep a constant load of 1210 N. and tried varying the inflation pressure between 2.4 to 1 bar. Even with a generous allowance for experimental error the effects are clear. The graphs show that the results appeared to fit reasonably well to a smooth line, there wasn't much scatter.
Point (1) on the curve with constant inflation pressure, shows how the actual contact patch pressure is lower (just over half) than the inflation pressure, or in other words the contact area is greater. This is due to the rubber surface compliance, thus this is more important at low vertical loads, whereas carcass stiffness became more important as the load rose as shown by points (3) to (6) where the actual contact pressure is higher than the air pressure, i.e. reduced area of contact.
Measurement setup. Various weights were placed on the end of a beam, which also loaded the tire via a thick plate of glass. The beam was arranged to apply the load to the tire with a 4:1 leverage. So a 25 kgf. weight would load the tire with 100 kgf. By tracing over the glass the contact area was determined.
The top plot shows the measured contact patch pressure at various wheel loads for a constant inflation pressure of 2.4 bar. The lower curves show the contact pressure at various inflation pressures for a fixed load of 1210 N. The numbers at the data points correspond with the contact area tracings in the previous sketch. The plain line on each plot shows the case of the contact patch pressure being equal to the inflation pressure.
The carcass stiffness helps to support the machine as the air pressure is reduced, the contact patch pressure being considerably higher than the inflation pressure. It looks as though the two lines will cross at an air pressure of about 3.5 bar. (although this was not tested by measurement), at which point the surface rubber compression will assume the greatest importance. This is as per the steel hoop analogy above.
We can easily see the two separate effects of surface compliance and carcass stiffness and how the relative importance of these varies with load and/or inflation pressure.
These tests were only done with one particular tire, other types will show different detail results but the overall effects should follow a similar pattern.
Area Under Cornering
Does cornering affect tire contact area? Let's assume a horizontal surface and lateral acceleration of 1G. Under these conditions the bike/rider CoG will be on a line at 45� to the horizontal and passing through the contact patch. There will a resultant force acting along this line through the contact patch of 1.4 times the supported weight.
This force is the resultant of the supported weight and the cornering force, which have the same magnitude, in this example of a 45� lean. The force normal to the surface is simply that due to the supported weight and does NOT vary with cornering force. The cornering force is reacted by the horizontal frictional force generated by the tire/road surface and this frictional force is "allowed" by virtue of the normal force.
Therefore, to a first approximation cornering force will NOT affect the tire contact area, and in fact this case could be approximated to, if we were just considering the inner tube without a real world tire. However in reality, the lateral force will cause some additional tire distortion to take place at the road/tire interface and depending on the tire characteristics, mentioned above, the contact area may well change.
Another aspect to this is of course the tire cross-sectional profile. The old Dunlop triangular racing tire, for example, was designed to put more rubber on the road when leant over, so even without tire distortion the contact patch area increased, simply by virtue of the lean angle.
by Ray Taylor
http://www.CarsNet.com/motorcycle
Ray Taylor owns the real world San Diego Auto Swap and also owns http://www.CarsNet.com and http://www.SanDiegoAutoSwap.com
Saturday, May 19, 2007
Do Electric Scooters Really Offer Better Alternative Transportation?
By Ahmed Bushra
There's a lot of hype over electric scooters these last couple of years, but is it really a wise investment?
Kids love them, but are they useful for adults looking to commute?
Many commuters, including college students, love the ease and portability of electric scooters. It is without doubt that the electric scooter has become a more than viable form of alternative transportation, and its here to stay...
This is because it is cheap to own, operate, and maintain an electric scooter. With gas prices rising, electricity is a much more inexpensive source of power.
The only real drawback of owning an electric scooter is the speed that they typically reach, usually between 18-25 mph, which can be quite slow. However, if you're only traveling within a 2 to 3 mile radius, then its the perfect solution.
There are a variety of styles and brands on the market, but as in any industry, you have your share of bad quality rip-offs and real brand-names.
Some of the better brand names include: Razor, Schwinn, X-treme, and Mongoose.
The typical standard warranty is between 1-3 months, with a 6-month warranty on batteries.
Batteries are re-chargeable, but the usual life is between 6-18 months, after which they need replacement. Its always wise to buy an extra battery for backup.
You can choose from 100 watts to 600 watts, with the most popular models being around 400-500 watts. The higher the wattage, the more weight the scooter can push and the steeper hills it can handle.
Hills are an important consideration when purchasing an electric scooter. Regardless of the scooter's power output, you'll notice a significant decrease in speed when going up hills. If you're planning to ride in a hilly area, then a gas-powered electric scooter is a better option, as long as its 49cc and under.
Legally, electric scooters are very well-appreciated. Most states do not regulate electric scooters the same way moped and gas scooter are regulated, in order to encourage the use of renewable energy and reduce pollution. Moreover, accidents associated with electric scooters are usually much less than with gas-powered ones.
Cost for the typical brand-name model is between $300 and $600, depending mainly on power output. Beware of buying on Ebay, because the scooter may not come with a warranty or availability of parts, two very important factors when considering a purchase.
The bottom-line is that electric scooters offer a very viable form of alternative transportation, and anyone commuting within a 2-3 mile radius should consider having one.
Learn more about choosing electric scooters here...
Ahmed Bushra owns and operates http://www.quality-discount-scooters.com, where he offers help, advice, and products to people looking for gas & electric scooters. If you want help choosing the right scooter, please visit his website: http://www.quality-discount-scooters.com
There's a lot of hype over electric scooters these last couple of years, but is it really a wise investment?
Kids love them, but are they useful for adults looking to commute?
Many commuters, including college students, love the ease and portability of electric scooters. It is without doubt that the electric scooter has become a more than viable form of alternative transportation, and its here to stay...
This is because it is cheap to own, operate, and maintain an electric scooter. With gas prices rising, electricity is a much more inexpensive source of power.
The only real drawback of owning an electric scooter is the speed that they typically reach, usually between 18-25 mph, which can be quite slow. However, if you're only traveling within a 2 to 3 mile radius, then its the perfect solution.
There are a variety of styles and brands on the market, but as in any industry, you have your share of bad quality rip-offs and real brand-names.
Some of the better brand names include: Razor, Schwinn, X-treme, and Mongoose.
The typical standard warranty is between 1-3 months, with a 6-month warranty on batteries.
Batteries are re-chargeable, but the usual life is between 6-18 months, after which they need replacement. Its always wise to buy an extra battery for backup.
You can choose from 100 watts to 600 watts, with the most popular models being around 400-500 watts. The higher the wattage, the more weight the scooter can push and the steeper hills it can handle.
Hills are an important consideration when purchasing an electric scooter. Regardless of the scooter's power output, you'll notice a significant decrease in speed when going up hills. If you're planning to ride in a hilly area, then a gas-powered electric scooter is a better option, as long as its 49cc and under.
Legally, electric scooters are very well-appreciated. Most states do not regulate electric scooters the same way moped and gas scooter are regulated, in order to encourage the use of renewable energy and reduce pollution. Moreover, accidents associated with electric scooters are usually much less than with gas-powered ones.
Cost for the typical brand-name model is between $300 and $600, depending mainly on power output. Beware of buying on Ebay, because the scooter may not come with a warranty or availability of parts, two very important factors when considering a purchase.
The bottom-line is that electric scooters offer a very viable form of alternative transportation, and anyone commuting within a 2-3 mile radius should consider having one.
Learn more about choosing electric scooters here...
Ahmed Bushra owns and operates http://www.quality-discount-scooters.com, where he offers help, advice, and products to people looking for gas & electric scooters. If you want help choosing the right scooter, please visit his website: http://www.quality-discount-scooters.com
Wednesday, May 16, 2007
Accessory Necessities - Advice for New Riders on Typical Bike Modifications
By Janet Green
The more you ride, the more you're going to notice "little things" that need to be addressed with further modifications to the bike. Fortunately, there are "after market" parts for every problem you'll experience. Here are a few of the more common post-purchase "mods" you might want to make!
Problem: You feel like those cows in the movie "Twister."
When you're ready to hit the highway, the first thing you'll notice is how windy it is out there and how much you feel like you and your bike are being tossed around, even on a day when the treetops aren't swaying in the breeze. That's aerodynamics at work: you on your motorcycle are meeting air as you travel, and the fact that you're basically a squared off, upright object is causing the air to hit you head-on in a most un-dynamic way. The need for protective eyewear quickly becomes apparent, and if you're wearing a helmet you'll notice that the force � even on a calm day � can push your whole head backwards as the air tries to make a kite out of your visor.
Solution: Add a windshield!
Adding a windshield to your bike makes the kind of night-and-day difference in highway riding that makes you smack your own forehead and ask yourself why you didn't do it sooner. The main thing the windshield does is deflect the frictional force that hits your body-and-bike "object" as it moves down the road. It doesn't help you much in the case of a strong cross-wind, but it definitely protects your head and body from taking the brunt of the air's force as you travel forward. It's important to note that it doesn't take a big, wide windshield to reduce this force. Even a small "sport" windshield will dramatically change the way air flows over your bike, reducing the air's impact on you. Don't feel like you have to settle for a big police cruiser-style 'shield if that's not the look you want.
Problem: Your bike emits a low, efficient "whirring" sound instead of a satisfying rumble
Solution: Pipe up!
Okay, we all know that the main reason to change those exhaust pipes is simple: we love the rumble, and we want to make some noise, good citizenship be damned! And, you can make a pretty good argument for the notion that "loud pipes save lives." But there's another reason to change out the pipes: different exhaust changes the way air flows through the bike's engine, which can give you more horsepower at higher RPM's. If you change your exhaust, you'll probably also need to re-jet the carbureator, to account for the easier-breathing engine. One down-side here is that you could lose pep on the bottom end: things may feel a little sluggish when you pull away from that intersection. So, while you might find that shiney new (rumbly) pipes will increase your hp and your overall "wow" factor, they also might change the way you feed the throttle when you take off from a stop.
Problem: your wrists ache from gripping the bars and keeping the throttle open.
Solution: Get a Grip � A hand-grip, that is!
The degree to which your hands, wrists and forearms ache after a ride can be addressed in a number of ways, not the least of which is to simply relax a little... if you're a new rider, you're probably using the "death grip" on those handlebars. This will quickly make your forearms ache, and simply relaxing your grip a bit will make a noticeable difference.
Your bike's handlebars and handgrips might also be causing you problems. Particularly with drag bars, which put your hands in a parallel-to-the-ground position when riding, comfortable handgrips might be an easy change that will make a big difference. If you have drag bars and find your hands aching, try putting on a set of comfort grips to provide some padding as your weight comes down on your hands and wrists. And, don't forget the wrist-rest! You can attach a simple little device to the right hand grip that allows you press down with the heel of your hand and open your fingers, keeping the throttle open while you relax your grip. This is, frankly, a life-saver on longer trips.
Problem: You have nowhere to put your stuff.
Solution: Bag it.
In the male world, it's probably bikers who can most identify with women who say they need a place to put their stuff. Those bar-hopping chopper guys aside, bikers who travel on their bikes appreciate their saddlebags, t-bags, and little pouches and pockets of every size and purpose. Fortunately, solutions to this problem are plentiful. Options range from large full saddlebags that mount on the back of the bike, collapsible rolling suitcases that attach to the sissy bar, to pouches that fit on the inside of your windshield or attach to your own belt loops for quick access to frequently-needed items.
Problem: Your bike seems dull, lifeless, utterly without bling
Solution: Go shopping!
This is why motorcycles are the perfect hobby for women who love to shop: there's always some bit of chrome you can add to brighten things up or some accessory you can add to make things more fun or more convenient. The possibilities here are endless, from a chrome choke knob cover or a fully-chromed engine and transmission case for maximum shine, to leather or vinyl saddlebags or other totes for maximum storage. And here's even MORE good news: you can pick a theme, and choose bits that dress up the bike in a highly personalized style. Trying to scare the kiddies? Try the skull theme! Want to create at least the illusion of speed, even while you're still learning? Maybe flames are for you! Finally, don't ignore yourself: that awesomely courageous, "I am Woman Hear Me Roar" rider � you deserve to outfit yourself in the best protective gear, the coolest biker-babe t-shirts, and anything else that tells the world "I ride and I love it!"
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
The more you ride, the more you're going to notice "little things" that need to be addressed with further modifications to the bike. Fortunately, there are "after market" parts for every problem you'll experience. Here are a few of the more common post-purchase "mods" you might want to make!
Problem: You feel like those cows in the movie "Twister."
When you're ready to hit the highway, the first thing you'll notice is how windy it is out there and how much you feel like you and your bike are being tossed around, even on a day when the treetops aren't swaying in the breeze. That's aerodynamics at work: you on your motorcycle are meeting air as you travel, and the fact that you're basically a squared off, upright object is causing the air to hit you head-on in a most un-dynamic way. The need for protective eyewear quickly becomes apparent, and if you're wearing a helmet you'll notice that the force � even on a calm day � can push your whole head backwards as the air tries to make a kite out of your visor.
Solution: Add a windshield!
Adding a windshield to your bike makes the kind of night-and-day difference in highway riding that makes you smack your own forehead and ask yourself why you didn't do it sooner. The main thing the windshield does is deflect the frictional force that hits your body-and-bike "object" as it moves down the road. It doesn't help you much in the case of a strong cross-wind, but it definitely protects your head and body from taking the brunt of the air's force as you travel forward. It's important to note that it doesn't take a big, wide windshield to reduce this force. Even a small "sport" windshield will dramatically change the way air flows over your bike, reducing the air's impact on you. Don't feel like you have to settle for a big police cruiser-style 'shield if that's not the look you want.
Problem: Your bike emits a low, efficient "whirring" sound instead of a satisfying rumble
Solution: Pipe up!
Okay, we all know that the main reason to change those exhaust pipes is simple: we love the rumble, and we want to make some noise, good citizenship be damned! And, you can make a pretty good argument for the notion that "loud pipes save lives." But there's another reason to change out the pipes: different exhaust changes the way air flows through the bike's engine, which can give you more horsepower at higher RPM's. If you change your exhaust, you'll probably also need to re-jet the carbureator, to account for the easier-breathing engine. One down-side here is that you could lose pep on the bottom end: things may feel a little sluggish when you pull away from that intersection. So, while you might find that shiney new (rumbly) pipes will increase your hp and your overall "wow" factor, they also might change the way you feed the throttle when you take off from a stop.
Problem: your wrists ache from gripping the bars and keeping the throttle open.
Solution: Get a Grip � A hand-grip, that is!
The degree to which your hands, wrists and forearms ache after a ride can be addressed in a number of ways, not the least of which is to simply relax a little... if you're a new rider, you're probably using the "death grip" on those handlebars. This will quickly make your forearms ache, and simply relaxing your grip a bit will make a noticeable difference.
Your bike's handlebars and handgrips might also be causing you problems. Particularly with drag bars, which put your hands in a parallel-to-the-ground position when riding, comfortable handgrips might be an easy change that will make a big difference. If you have drag bars and find your hands aching, try putting on a set of comfort grips to provide some padding as your weight comes down on your hands and wrists. And, don't forget the wrist-rest! You can attach a simple little device to the right hand grip that allows you press down with the heel of your hand and open your fingers, keeping the throttle open while you relax your grip. This is, frankly, a life-saver on longer trips.
Problem: You have nowhere to put your stuff.
Solution: Bag it.
In the male world, it's probably bikers who can most identify with women who say they need a place to put their stuff. Those bar-hopping chopper guys aside, bikers who travel on their bikes appreciate their saddlebags, t-bags, and little pouches and pockets of every size and purpose. Fortunately, solutions to this problem are plentiful. Options range from large full saddlebags that mount on the back of the bike, collapsible rolling suitcases that attach to the sissy bar, to pouches that fit on the inside of your windshield or attach to your own belt loops for quick access to frequently-needed items.
Problem: Your bike seems dull, lifeless, utterly without bling
Solution: Go shopping!
This is why motorcycles are the perfect hobby for women who love to shop: there's always some bit of chrome you can add to brighten things up or some accessory you can add to make things more fun or more convenient. The possibilities here are endless, from a chrome choke knob cover or a fully-chromed engine and transmission case for maximum shine, to leather or vinyl saddlebags or other totes for maximum storage. And here's even MORE good news: you can pick a theme, and choose bits that dress up the bike in a highly personalized style. Trying to scare the kiddies? Try the skull theme! Want to create at least the illusion of speed, even while you're still learning? Maybe flames are for you! Finally, don't ignore yourself: that awesomely courageous, "I am Woman Hear Me Roar" rider � you deserve to outfit yourself in the best protective gear, the coolest biker-babe t-shirts, and anything else that tells the world "I ride and I love it!"
Janet Green is the editor and chief biker chick at Biker Chick News, a popular web destination for women who ride motorcycles. For her complete ride journal, plus news and links of interest to women who ride, visit http://www.Bikerchicknews.com.
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