Suspension Basics

KTM Mike

Mi. Trail Riders
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#1
I have not ever really messed with suspension set up, but have some very basic ideas of what to look for... but really have no clue if I am "reading" what my bike is doing and relating that to what clicker to spin etc!

so - what are the signs of:

to much or to little compression dampening, rebound etc. to much/little preload/sag, wrong spring rates?

what traits would the bike show when things are out of whack?

I am attempting to dial in my 97 KTM 300EXC (bought it used dont even know what stock settings are), have made some minor progress but - always looking for more. any specific suspension set up suggestions? 190 lbs plus gear, beginer C class enduro racer, trail rider.

specifically i am hoping to get the bike to do better in the endless whoops around here! also - back end tends to kick up on sharp edges (rocks and roots) i believe thats to much compression dampening (?). bike tends to push the front occasionally (to much sag in the rear?)

any advice appreciated (other than sell the KTM - I love it!)
:confused: :confused:
 

KTM Mike

Mi. Trail Riders
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#3
smilinicon

thanks for the link - mx techs site does provide a lot of what i was looking for. How is MX tech with setting up off road bikes? are there others who specialized in off road vs mx?
 
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#4
Yes, there are many who setup suspensions (MX and off-road). I have dealt with Jeremy Wilke in person and I was impressed with his integrety, so I use MX-Tech. Set sag measurements and then use the tuning guide... if you cannot work a handling symptom out by a combo of clickers, oil height and preload adjustments, then consider a re-valve job.
 
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#5
susp

i keep a log of track ,track cond. , tire press., susp. settings,,etc.....,how it all worked and what might be better,,,this is a great help so you dont go chasing your tail!!! its real easy to make a quick basic form in any word processor software,, put it in a 30 cent binder and keep it in your gear bag,,,, it really is a big help,,,,and remember if your riding woods,, too much rebound will result in broken bones very quickley,,,it takes just one root!!! good luck....cw:scream:
 

HiG4s

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#6
Atlanta, MI< isn't that near Rose City? I use to live in MI and ride up there once an awhile. Yeah there are lots of sand whoops there, but I found even more down here. I'm still trying to get my Husky dialed in, so far it doesn't compare to my old 89 KTM 250/EXC in the whoops. I would expect you will be able to get a 97 set fine to handle the whoops without a re-valve as long as you have the right springs for your weight. Of course, everyone I have heard of that had Jermey redo their shocks and forks has said they came back way better than stock.
 

KTM Mike

Mi. Trail Riders
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#7
Originally posted by HiG4s
Atlanta, MI< isn't that near Rose City? I use to live in MI and ride up there once an awhile. .....I would expect you will be able to get a 97 set fine to handle the whoops without a re-valve as long as you have the right springs for your weight.....
Yep - Atlanta is about oh, 50 or 60 miles north of Rose City, 32 miles east of Gaylord. tons of whoops -but also i run into fair bit of roots etc. On Sunday i rode the Hunt Creek loop and some of the MCCT that goes south down to it.. mix of sections with tighter stuff with rocks and roots then sections with sandy whoops... and i am now learning those are likely the two extremes of suspension set up!

cw242 - the log book is a great idea... now if i only had the time to really mess with all this..., hmmm broken bones... been there done that a few times to many... hold on while i go check my rebound! :scream:

it sounds like the next thing i had better pin down is the spring rate issue - sag etc before i can really judge the rest of it. 95 mm seems to be the hot number for rear sag... i have no idea where my bike is... stay tuned! thanks again all for the advice
 
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#8
why doesnt MX-TECH.COM have a tuning guide up for MX? They have awesome information on their other guides but i was looking forward to seeing an MX guide. Does any other suspension sites have a tuning guide for MX?
 

Jeremy Wilkey

Owner, MX-Tech
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#10
It's burried in the down loads..


Getting started, shock:
Setting the rebound:
1.) Find a relatively fast straight with braking bumps leading into the entrance of a corner. Reduce (Turn clicker out) the rebound damping until the rear end begins to hop or feel loose. Finally, increase (Turn clicker in) the rebound damping until the sensation goes away.
2.) Find a jump that tends to launch the motorcycle out. The rear end should absorb and then smoothly lift the motorcycle into the air. If the rear end bounces up, add rebound. (Turn clicker in)
3.) Find some large whoops. The motorcycle should track straight through the whoops with the rear wheel extending to the ground before the next impact. If it does not perform as described as above, it is packing and the rebound damping should be reduced! (Turn clicker out) (Please note the guide for sand set-up, as these rules don't apply for sand.)
Setting the compression:
1.) Find a corner with acceleration bumps on the exit. The rear of the motorcycle should follow the ground. If the rear end "breaks up", soften the compression. (Turn clicker out) (If this fails soften the rebound two clicks.) (Turn clicker out)
2.) Find some rough sections, a large jump and a couple of "G-Outs". The shock should bottom on the roughest section but it should not be a slamming sensation. Add compression to fight bottoming. (Turn clicker in.) But avoid going to far as small bump ride will be sacrificed in the trade. Remember the adjusters have a primary effect on the low speed, so even a large change in setting may only affect bottoming resistance slightly. Remember bottoming your suspension is not necessarily a bad thing. You should strive to bottom off the biggest bottoming load obstacle on the track. If you don't you're not getting maximum plushness from your suspension.
Getting started, forks:
Setting the compression:

1.) The forks should react to all track variations. If the forks seem harsh on small bumps or holes, soften the compression. (Turn clicker out) If they aren't, stiffen (Turn clicker in.) until they do feel harsh and then turn back a click or two.
2.) Now find the rough part of the track again. The forks should bottom over the worst obstacle. If harsh bottoming occurs, add oil in 5 mm increments.
Setting the rebound:
The rebound damping is responsible for the stability and the cornering characteristics of the motorcycle.
1) Find a short sweeper. When the forks compress for the turn, the speed at which the forks return is the energy that pushes your front wheel into the ground. If the forks rebound too quickly, the energy will be used up and the bike will drift wide, or wash. If the rebound is too slow, the bike will tuck under and turn too soon to the inside. Find the appropriate balance for each track.
2). With the bike turning well, the wheel should return to the ground quickly yet not deflect off berms or bounce off jumps.
Going to different tracks:
For hardpack to intermediate:
Set the compression softer, (Turn clicker out) front and rear to help get maximum wheel contact and plushness.
Sand tracks:
(Non-square edged bumps); More low speed compression and rebound are necessary. Start by adding 1-2 clicks (Turn clicker in.) of rebound and as the track gets rough, add compression 1-4 clicks. (Turn clicker in.) (Supplementary sand set-up techniques). Harshness is a result of packing in forks. Remember to add compression (Turn clicker in) to help keep the front end from packing. The rear suspension will exhibit packing by swapping. To eliminate swapping begin adding compression (Turn clicker in) until the bike tracks straight and then add rebound (Turn clicker in) to keep the rear following the terrain of each whoop. Don't be concerned if your clickers are nearly maxed out in sand conditions. Unless of course you had your bike revalved for sand.
Supercross:
(G-load, curb hits); G-loads produce slow piston speeds. This means that less dampening is produced by the shock and forks in a situation that causes more of a bottoming load. To set your bike up for Supercross adjust the compression stiffer (Turn clicker in) on the suspension (2-6), clicks and in some circumstances raise oil level and/or change to stiffer springs.
Unpleasantries?
Headshake:
Adjust the forks lower in the triple clamps.
Excessive rear end kick:
Check for packing, which is identified by kick to side in hard to loam conditions. If you observe packing, soften rebound. (Turn clicker out.) This cannot be avoided if you brake improperly and lock the rear wheel up and/or pull in the clutch, on the entrance to corners.
Keep a record of the different settings if you race different tracks. That way you can start at a point that worked well the previous times.