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Posts posted by snowman

  1. I asked the same question the guys from Continental at the June CSS at Silverstone. They replied the most important reason for not running the tyre in the opposite direction is hidden in how the tyre is actually constructed.


    Simply put the core of the tyre is made out of a long strip of "rubber". In order to make this strip a circle you have to connect its ends by overlapping them so that one is over the other. The correct direction of rotation of the tyre is such that while rotating it doesn't "hit" the edge of the overlap to eventually cause a critical damage.


    That was enough for me to stop flipping tyres :)




  2. Thank you all for the interesting discussion. I learned some curious facts - hope you did so too.


    Now, I'd like to underline what we seem to have agreed upon - rear tyre's larger patch alone does not give it better traction than the front tyre.


    If this is true I'd like to "challenge" the cornering guru Keith Code to share his opinion on the topic. As far as my memories don't play funny tricks with me I think Keith said in a movie of his that we have to roll on the throttle evenly smoothly and continuously throughout the turn so that we offload the front tyre *AND* make use of rear tyre's larger contact patch.


    I tried this technique thanks to CSS and it definitely makes miracles. BUT is the second part of the sentence true? Can we really load the rear tyre more than the front because it has a larger patch OR do we just have to offload the front as it needs grip to counteract cornering forces and to also steer the bike vs the rear tyre only having to counteract the cornering forces?


    I know many people say that you need to ride and ride and ride and not to look so much into theory. However I believe that understanding how things work can actually help you make better decisions when you need to. And maybe be less afraid of myths like "I can't ride faster because I do not have enough contact patch"...


    Thanks and hang on - spring is knocking on the door :)


  3. You will probably need powersteering to control a 180-200 mm front tyre under racing conditions. The effort required to turn the motorcycle would be massive with a big tyre. Also, the steering influence from a wide tyre when leaned over would be very hard to deal with when riding on the edge; the rider could in an extreme situation see the handlebars ripped out of his hands. Hitting the brakes mid-corner with such a wide tyre would probably be impossible. Also, it is likely that the higher weight would upset the delicate front suspension more than the rear since the fork also must deal with steering.


    I agree but I'd rather argue why the rear tyre is not as slim as the front one. Older bikes actually do have narrower rear tyres. What do you think?

  4. It's interesting to note that bicycles do not have wider rear tyres. So it probably has to do with the fact that there's an engine attached to the rear wheel. Thinking about it even the F1 cars have a lot wider rear tyres as these tyres have to transfer great power to the tarmac.


    There's even a wikipedia article here http://en.wikipedia.org/wiki/Motorcycle_tyre but it does not say anything about tyres' width.


    I hope Steve Brubaker from Dunlop will notice the topic and give some insight into this.

  5. Hey all,


    I read this article http://www.stevemund...m/friction.html and it kind of turned my understanding about traction and contact patch size around.


    If I understand correctly contact patch size doesn't matter as far as friction is concerned. All that matters is:

    1. Friction coefficient (something we cannot influence as it depends on track surface and tyre compounds)
    2. Bike + rider weight

    Well then where's "contact patch" in the grip equation? If I remember well Keith explained that by rolling on the throttle smoothly while in the corner you actually make use of the larger contact patch of the rear tyre which can carry more load. If this is true it seems these pieces of information contradict with each other.


    What is your opinion? What's the point of having a larger tyre contact patch?




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