Holding Your Line

[Cobie Fair]

Cobie, just so you know I bought TOTW II dvd. I think there is a shot on the steering bike with 2 up riders. The rear rider was steering while the front rider was controlling the throttle. The amazing shot was when after making the steering input into the turn the rear rider let go of the steering handle bars, while the front rider kept on the throttle. Bike still turned on its line.

And yes there is a cameo appearance of you in this dvd too.

 

Quite right there is a cameo--I'm the rider in front on the No B/S bike

 

CF

[636rider]

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Is it because the change in trail cause the bike to turn in more suddenly, changing the radius of the turn too quickly and increasing the centripetal acceleration so quickly that the friction of the tire is overwhelemed? This makes sense, as it is only the front wheel that gives way.

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R Sole,

This makes sense to me too.

[636rider]

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I came up with a few theories:

1) Perhaps the weight shift to the front of the bike causes the forks to dip, and the steering geometry to change, causing a quick change in turn in (i..e a suddenly decreasing turn radius) that increases the cenripetal forces due to the sudden changes in radius? To my mind then, this effect would not be seen in bicycles with no suspension? maybe a cyclist can confirm this?

 

2) Is it because the sudden deceleration causes the front tyre to start skidding, and the dynamic friction afforded by a slipping front tyre is a lot less than the rolling friction? Although this does not make sense as there si noreason the tyre would not just continure to roll?

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It seems 1) is reasonable. Due to sudden "increasing" of centripetal force, there is additional forward component of the centripetal force, so that the front tire needs to fight the original centripetal force plus this new slightly forward component---the tire keeps on rolling, but also slipping to side-forward until down too.

[Shakespear]

Thanks K,

I love it when you give us drills like this to master a technique. I have often felt like I can't wait to try something like this after getting it from you.

Nic