harsh high speed damping

[bth2]

hi all,

i am running road tyres and have a 90 nm spring in the rear. 12,000 miles.

i am very happy with the rear slow speed damping, in fact its really quite plush. unfortunately the high speed damping is very harsh and the rear skips off ripples under load(if you get what i mean).

tyre pressures = 32 - 36 . rear rebound damping 4 out from closed, rear compression 2 out from standard. my sag ,at last check , was ok.

the effect i have had is ,hitting a pothole or ripples mid corner, and the bike feels solid ,no damping and the bike looses traction and jumps sideways. obviously this only happens in certain circumstances but is a right pain sometimes.

 

any ideas ?

[williestreet]

Personally I think you have rebound set too slow.

 

When hitting bumps you want the shock to extend quickly and allow the tire to stay in contact with the road.  This becomes even more evident when leaned over.  Shock can't extend quickly enough and the rear feels like it's sliding because the tire is not putting force through the tire to the road and the tire slides sideways.

 

I run a 90N spring as well and would suggest turning the rebound adjuster fully clockwise and then setting it between 10-12 clicks out.  I run 11 out.

If you make this one adjustment and ride the bike I will bet you will now feel the bike  wallowing.

 

In my opinion it is because the shock has not enough slow speed compression.  This allows the rear to drop in it's stroke far too much on rolling bumps or sharp bumps.  Then the rebound has trouble controlling all that energy when it tries to extend.  Many will put more rebound into the shock, but in my opinion it needs more compression damping to prevent the shock using so much travel.

 

Try setting the compression to 6 clicks out from fully clockwise.   This will absorb the bumps and keep the bike from going so far into the stroke.  Rebound will have an easier time controlling the spring.

Between 4-6 clicks out the rear starts to feel more normal and controlled.  If you go too low the bumps will start to feel a bit harsh.  Back out another click if you get this sensation. 

I am at 5 clicks out.

 

My shock will get re-valved this winter for more Slow speed compression damping, but this is my fix for now.

 

Just my opinion.

 

 

 

 

 

 

 

 

Edited August 23, 2021 by williestreet

[gone2seed]

what he said. I am running the stock shock with A 8.8 spring. Working better than the forks with a .66 and race tech base valves. (race techs recommended valving is to stiff.IMO)

  Suggestion. Play with it. Take a screw driver on the next ride. Find a stretch  of bumpy road  and  run across it making changes. 

  See what works for you.

[Goldentaco]

90% of the time if you’re losing grip/drive/traction on washboard/stutter bumps it’s rebound not fast enough. 
 

Loosen it. When bike gets bouncy, tighten it. 
 

Loosen=turn Counter clockwise. 
Tighten=turn clockwise. 
 

J

[bth2]

thanks all for the great replies. as willistreet mentioned. i do have the rebound too slow because of the wallowing mentioned. feels great some of the time but not doing the more important job. 

i will try your settings and see where i am.

let us know how you get on with the revalve. i was thinking along those lines but may opt for a new shock when my oem shock is u/s.

 

cheers

brian

Edited August 23, 2021 by bth2

[bth2]

tried new settings today and tested to and from work.... much better. it seems i have been going the wrong way.

big thanks.

brian