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Discussion Starter · #1 ·
Hey guys, this is kind of a technical question so if you know the answer to this please elaborate. I was talking to someone about the traction of the tires. He told me that as you go faster, the coefficient of friction is actually increased on the tire itself, which in laymens terms means you have more traction. Basically, he said that as you go faster, you can picture your tire unravling and having more contact patch with the road. (faster you go=more tire contact per time= more traction) Now, I know temperature has a huge factor on this but I want to leave that out because i'm just dealing with tire contact patch with the road per time (seconds for instance).
Does this make sense to any of you guys? If so, does this explain why I can be going through the city streets through a sharp turn at low speed and feel "slippage" of my front or back tire without being in such a lean angle...vs....hauling ass through the exit ramps of freeways at sharp lean angles with no slippage whatsoever. (not taking tire temperature into account) If you know the physics of this, I would love to know!
 

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Warning: science content

The coefficient of friction between your tire and the road does NOT increase with speed, it is a constant (for all practical purposes). Yes, the coefficient of friction can change but since the coefficient of friction is a fraction (greater than 0, less than 1) any changes due to speed, temperature, etc., are negligible. Study after study have shown that the most important factor is the road surface. However, the faster your tire spins the taller it gets, meaning less rubber is in contact with the road, meaning less friction (due to reduced contact patch) in a straight line. When you lean into a corner your speed has decreased and your suspension is loading the tire causing the contact patch to flatten (very slightly) increasing your contact patch and traction. The most important variable relating to the coefficient of friction in a traction scenario will always be the quality and cleanliness of the road surface.
 

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If you watch top fuel drag racing, you can see what I think your friend is talking about. The tire will increase in diameter from the centrifugal force. While this may make for a potentially longer contact patch it narrows the width of the contact patch. However a drag slick and a motorcycle tire are different types of construction and I can't imagine there is any tangible effect for a motorcylce tire.
 

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The coefficient of friction between your tire and the road does NOT increase with speed, it is a constant (for all practical purposes). Yes, the coefficient of friction can change but since the coefficient of friction is a fraction (greater than 0, less than 1) any changes due to speed, temperature, etc., are negligible. Study after study have shown that the most important factor is the road surface. However, the faster your tire spins the taller it gets, meaning less rubber is in contact with the road, meaning less friction (due to reduced contact patch) in a straight line. When you lean into a corner your speed has decreased and your suspension is loading the tire causing the contact patch to flatten (very slightly) increasing your contact patch and traction. The most important variable relating to the coefficient of friction in a traction scenario will always be the quality and cleanliness of the road surface.

exactly. I agree 110% the faster your going the more your suspension loads, the bigger your contact patch gets.
 

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Can't the coefficient of friction be higher than 1 when you bring the sticky factor in. IE dragster tires pulling upwards of 4-5 g's.
 

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Discussion Starter · #6 · (Edited)
Wow, thats really interesting! That really starts to make more sense now. I never even considered the increased suspension load (hence increased traction) into the equation. That, including the warmed up tires can defintetly explain why you can haul ass around turns at high speeds. The more I ride, the more I realize it can be an art and skill that never ends! :cheers-004:
 

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the bikes suspension is designed to put traction where its needed when its needed, for instance if you hit the throttle real hard the back tire will plant thus giving the tire more "stick" if you will, & same goes for when you hit your brakes the bike then plants the front & gives more traction there
 

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i'll throw another in the mix.

at high speeds, when straight up, the rear tire will slip some. this is why long highspeed runs wear tires out fast. theyre constantly slipping, if only ever so slightly.
 

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Discussion Starter · #10 · (Edited)
good point!

i'll throw another in the mix.

at high speeds, when straight up, the rear tire will slip some. this is why long highspeed runs wear tires out fast. theyre constantly slipping, if only ever so slightly.
yep, and i think this video shows what you mean...wait till the end! :buzzsaw:Think also about all that air you gotta push when your tire is fighting the road too.

http://www.youtube.com/watch?v=CT-wrLOY4q8
 
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