Fork angle question

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Mar 14, 2001
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#1
is there an optimal fork angle for all around conditions, reason i ask is, my friend who has the same bike as i do, but he is shorter, so he took the bike to the local suspension guru here De Wayne Jones, to lower the ride of his cr125. he shaved the seat, and lowered the forks and rear susp. the front fork is way lowered, the tops of the forks are well through the top triple clamp. he adjusted the rear to match. did all the shock settings sag etc.
after all that i took the bike out to try it out. the bike turns so well,
i'm guessing thats beause the forks are shortened creating a shorter wheel base. but i overheard de wayne jones say angle is important too. i'm probably just gonna get my suspension set up by him too, but i'm just wondering if there are certain parameters for fork angle.
 

marcusgunby

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#2
There is no optimum fork angle it has to be determined by a huge number of variables like weight/c of g /intended use/trail and im sure hundreds of others ,this is why teams soends hours playing with different setting trying to get the best compomise.I once rode a trail bike on a mx course and it too steered way better than my Cr but i wouldnt like to hit 4th gear bumps on it. :p
 

Jeremy Wilkey

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#3
Mr. Jones is a FT guy primarly and fork angle in FT is a issue.. But swingarm angle is even more important..

Jer
 

JTT

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#6
Jer, I'm curious, you mentioned swingarm angle being important, but aside from moving the pivot piont, how do you lower a bike without effecting the angle?
 
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#7
Using a simple background would show that depending on the angle the fork is at, the forces exerted will vary, so changes in specs of tube diameters, materials, etc has to be determined. Also, a fork that has more rake will probably need somewhat stiffer valving for little stuff yet need softer valving for jumps. I'm not sure if this is exactly right but using 2nd year physics courses it seems to work in my head. :P