Suspension guru's...

[Concep Two9]

How much effect does the rear wheel position in the swingarm have on rear shock performance? I'm thinking my KX250 wheel is too far back and softening the action, to where it's hard find a good setting.

[alward25]

What is the shock's history? spring, valving, service.  Is your spring for your weight?  Sag?  If the wheel is all the way back is will affect performance, more leverage.  Wrong spring is frequently the problem. 

[Concep Two9]

Thought I might get those questions, so.. PC revalved set up for me, last service was around 6 months ago, with 4-5 rides since. Static sag is in the right range so my spring should be correct. Race sag, 100-103. The problem is I'm having to dial in more compression than I think should be nessesary, to rid the to-soft feel. The wheel IS pretty far back, so considering knocking out a chain link to see if that helps.

[Dutch-K5 Fan]

I don't think there's much difference between race sag with wheel up front, and wheel al back.
Can be measured easy without chain to be sure.
For my self have never feld much difference.

Have been reading the Suspension Bible from Race Tech for 3 weeks now, it's real fun.
On the chapter: Troubleshooting it says.

SHOCKS
Feels Loose/ Shock Pumps:

A: not enough low-speed rebound damping
B: not enough high-speed rebound damping
C: not enough low-speed compression damping
D: springrate too soft
E: too little preload

So testing is the only option to find out if it's A,B,....... or E

Hope it helps.

Dutchie

[don46]

Wheel position can have some effect the further back will create more leverage, but, I wouldn't think it would be significant. Have you checked your Nitrogen pressure or had it recharged? you will need a bottle ant the right set up to do it properly, if you check it using a gauge you will lose to much pressure and that will make your shock really soft. Nitrogen pressure does help a little bit.  I would think that a couple of clicks of compression would help your cause, if it kicks after compression then I'd add rebound.  some valving makes very little difference till you get almost all the way in or out

[Sapper]

The positioning of the rear wheel fore or aft isn't going to have any effect when only moving less than an inch. Granted the front wheel placement has an effect due to it being the lead wheel. The rear wheel trails.

I'd say it's either in your track conditions and the suspension isn't set up for it or your adjustments aren't right. Since you said it was built for you, I'd set the clickers in the middle and start from there.

I have all the settings written down for my sons bikes, for the tracks we frequent based on track conditions. Muddy, hard pack, loamy, etc. Even fork height settings. I don't make an absolute science every race like the pros do, these are just things I did along the way and wrote them down and it helps.

[Concep Two9]

Thanks for the input!, I also had a couple tuners offer some thoughts, here's what they had to say;


Actually the position has a lot more to do with sag numbers than actual suspension action / although the engineers here will dispute that /  its just what you feel as a rider You will be able to feel how it wants to 'turn in ' longer - slower / shorter - quicker - the latest bike to really feel the effects of the rear wheel is the 10-13 yz450f . If you moved it from the front of the slot to the rear , then that huge change would probably need a little compression tuning as well .Small changes / like adjusting the chain , you wont feel anything



For the most part, damping is a velocity (shock compressive/rebound speed) sensitive feature - force relative to speed.  Moving the wheel around within its limits won't change the shock speed much so it won't have much of an effect on the damping.  Spring rate is a position sensitive feature - force relative to position, and moving the wheel back gives more leverage on the linkage so you will end up with slightly softer suspension.  If you move your wheel around, just re-set your sag and you should be fine.  There shouldn't be much of any change to damping. 

[ewilly]

I am always looking for suspension tricks to avoid paying $$$

THX