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Old 08-18-2005, 10:33 PM   #1
Thorny OP
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Joined: Aug 2004
Location: Rocky Mountains
Oddometer: 496
Question HELP: Fork Setup Question

I am looking for opinions on how the ride height of the front fork will affect the handling of my bike. The two pictures depict the top of the fork tube comming through the top of the upper clamp and bumping into the bottom of the handle bars.

LOW HEIGHT:

jimbud > Rampart Range photo

HIGH HEIGHT:

jimbud > Rampart Range photo

So again: how will the two extremes of setup affect ride and handleing.

Things to consider: I am plagued with a high speed head wobble, possibly due to poor front tire choice, or perhaps I did not return the front ride height to the same spot as it was in when stock. Other thing to consider is that I use the bike for hard riding off road including jumps, rocks, and other "Esteban trail" type of conditions.

Oh, and seat height is not an issue for me.

thanks for your oppinions.

Josh.

JBudimlya screwed with this post 08-18-2005 at 10:43 PM
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Old 08-19-2005, 03:14 AM   #2
rjf
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Location: Gosford, NSW, Aust. Scrambler, 640Adv, 300EXC
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Hi, I typed my explanation inside the quotation 'cause I wanted to use the pic's. I hope this helps ya half as much as the answers I've got to Questions around here
Quote:
Originally Posted by JBudimlya
.
Suspension tuning is bit of a black art, but heres my take on your question. ( be aware that as you move the fork position in the triple clamps you also alter the weight balance front to rear a little, which effects the damping characteristics a little, etc. also things like different tires, tire presures, shock settings, etc will also effect stability )

LOW HEIGHT:This raises the front of the bike, increasing the rake. Think of this as making it like a chopper - stable in a staight line, but is slower turning / takes more effort to turn.

jimbud > Rampart Range photo

HIGH HEIGHT:this lowers the front end of the bike, decreasing the rake. This makes it more like a sportsbike - Less stable but quicker turning / takes less effort to turn

jimbud > Rampart Range photo

Its not always that clear cut. On my R1 I lowered the front end to help it turn in Quicker. Suprizingly it also made it more stable cause it put extra weight on the front wheel, keeping it planted on the deck making the forks compress over bumps, instead of skimming the ground and making the bars flick sideways over bumps.
I've also experienced "a high speed head wobble" on my 640 adventure when I changed to Michelin Desert tires 3 weeks ago.
If I was in your position I'd set the top of the forks level with the top of the triple clamp, adjust the spring preload to the get the correct sag setting front and rear. (You ain't got external preload adjusters by the looks of those pic's), then start experimenting with the damping adjusters, starting with more compression on the forks to try and keep them higher in the stroke = more rake - more stability.
Also, some people say that steering stabilizers are a baid aid solution. I think every bike should have one.
Rhys.
Josh.
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Old 08-19-2005, 09:03 AM   #3
Jan from Finland
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Quote:
Originally Posted by JBudimlya
I am looking for opinions on how the ride height of the front fork will affect the handling of my bike. The two pictures depict the top of the fork tube comming through the top of the upper clamp and bumping into the bottom of the handle bars.
Here are two links for suspension set-up basics:

http://www.ohlins.com/pdf/07251-02.pdf (See General Handling set-up)
http://www.sportrider.com/tech/146_0006_susp_handle/
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