Ohlins DU440

[Speeddog]

Did you have the stock spring on yours?

It had a 1091-31/95, then I swapped in a -34/100.

Currently running a 600 lb/in spring on the Penske.

180# in street clothes, likely pushing 200# with gear.

[ducpainter]

It had a 1091-31/95, then I swapped in a -34/100.

Currently running a 600 lb/in spring on the Penske.

180# in street clothes, likely pushing 200# with gear.

Do you recall how much preload you needed to get the desired sag?

The only reason I ask is I don't find my Ohlins harsh at all and the stack is OEM with a stiffer spring.

[Speeddog]

On install, I set 17mm for the /95 spring, 13mm for the /100 spring.

But I was running the hydraulic preload adjuster, so it could have easily varied a good bit from that.
And I like running quite a bit of sag.

My Ohlins could have been fiddled with before I got it, 10 years old then and no way to tell.

[koko64]

It had a 1091-31/95, then I swapped in a -34/100.

Currently running a 600 lb/in spring on the Penske.

180# in street clothes, likely pushing 200# with gear.

You've made me re-evaluate my weight estimation. 200 in shorts and 210-220 in gear. The 440 is so composed and road holding is superb, but it's touring plush with the 110lb GLW riding pillion. Brings to mind your description of the compression damping as "firm". I think the spring code is well erased with time, but I may just adjust a click or two and fine tune spring preload.

That Penske was a beautifully crafted shock. It was a whole kilo+ lighter than the oem Sachs/Boge too.

[koko64]

So set the damping at stock spec and adjusted from there. I note that backing off the comp damping only lets the shock fall into its stroke too quickly so it stays at the base setting of 12 clicks out. I can fine tune overall compliance Vs control via the rebound clicker which still clearly has an effect on either fast or slow speed compression damping. I suspect it affects high speed comp damping while the comp knob controls slow speed comp damping or how quickly the shock falls through its stroke. So I'm using the comp knob to provide control and composure of the rear end while using the rebound wheel to manage overall compliance. Does this sound correct to you suspension guys?

[ducpainter]

I've never touched the rebound. I only adjust the remote reservoir and am happy.

Keep in mind...I never felt the vibration of a left main bearing that was failed.

The vet suspects the piston had been hitting the head for quite some time.

It's all perspective.

...which reminds me...I need to call him about the replacement motor that I also blew up...

[koko64]

 

[Moronic]

So set the damping at stock spec and adjusted from there. I note that backing off the comp damping only lets the shock fall into its stroke too quickly so it stays at the base setting of 12 clicks out. I can fine tune overall compliance Vs control via the rebound clicker which still clearly has an effect on either fast or slow speed compression damping. I suspect it affects high speed comp damping while the comp knob controls slow speed comp damping or how quickly the shock falls through its stroke. So I'm using the comp knob to provide control and composure of the rear end while using the rebound wheel to manage overall compliance. Does this sound correct to you suspension guys?

Hard to say from where I sit. In practice, my approach follows ducpainter's. Difference being that I reached my preferred rebound setting from trial and error. I have found a rebound setting that works everywhere, and I adjust compliance with the compression knob.

If you take a look at the chart MonsterHPD posted:



you can see that the rebound adjuster has only a small effect on compression damping, and that what effect there is becomes more prominent at high deflection speeds. (Upper curve is compression, speed rises left-to-right, chart shows rebound and compression at a range of settings for the rebound adjuster.)

So as the chart shows, using the rebound adjuster has a way bigger effect on rebound than compression.

However, adjusting rebound affects compliance, because it affects the ability of the shock to recover from one bump before it encounters the next.

Therefore my guess is that what you are feeling when you use the rebound clicker is the effect of the rebound damping on compliance at different settings (and not so much the effect of the rebound clicker on compression damping).

That is only a guess, obv.

It occurs to me - and this too is only a guess - is that the shock has too much rebound at the Ohlins reccommended rebound setting. So it is packing down a bit.

Have you tried running four clicks less rebound than Ohlins rec?

[koko64]

Thanks. That's exactly where my adjustments ended! That really helps explain what I'm feeling with the shock. And yes, I have the rebound now set at 18 clicks , so 4 more clicks out from the oem setting of 14.  [thumbsup]I first tried 16, then 18 and it's a good compromise. Playing with the compression has given me no joy and reducing  compression damping lets the shock collapse too quickly while increasing compression damping creates a harsh ride over sharp bumps. The stock compression setting works quite well.

[Moronic]

Playing with the compression has given me no joy and reducing  compression damping lets the shock collapse too quickly while increasing compression damping creates a harsh ride over sharp bumps. The stock compression setting works quite well.

This doesn't sound quite right. Might just be the language you've used. But I would expect the effect of a single click on the compression knob to be subtle. And therefore that you could use that clicker helpfully to tune your ride for different conditions.

I would expect ride compliance to improve as you wound off compression, and without any downside when you're just tooling along in a straight line.

Adding compression from minimum should then progressively firm up the rear for when you're working the bike.

It may be that the OEM compression setting is as firm as you ever need. But you should get more comfort (albeit less stability) as you wind the adjuster in the direction of soft.

Interesting that you like 16-18 out on the rebound. As I've said above, that's about where I am (on a different shock, but one that may well have the same rebound stack).

[koko64]

"Seriously, I feel one single click of compression but the rebound is less stark, but noticeable."

Edit
Testing has shown me that high speed (sharp edged bumps) are easily felt with a single click but low speed not so much. Rebound is felt more per click  for slower more rounded pot holes an d depressions causing severe packing if I went too far. After lots of testing I now think the rebound is the more intrusive adjustment

[koko64]

I have kept a record of all my adjustments, so I have set the compression damping knob all the way out (-12 clicks) to take it out of the picture and play with the rebound damping at 16 and18 clicks out (-2 & -4 from stock). A ride through the local hills left me feeling some packing at 16 clicks so now I will play with 18. Once I'm happy with rebound damping I'll add some compression damping and see how I feel. You guys are correct about there being plenty of built in compression and rebound damping on these shocks and my mistaking packing for compression harshness because the bike is well composed with all clicks out on the compression knob and I can feel the bike staying down or packing on deep, long potholes or hanging up on the crest of bumps with oem rebound settings.
Thanks for your guidance fellas.
On the track I find suspension set up so much easier.

[Moronic]

Sounds like you're on to it now. 

Good luck, and keep us posted.

[koko64]

Thanks again fellas.
Cheers.

[koko64]

Still fooling around with the shock.
Comp damping all the way out.
Rebound damping played with from a baseline of 14 out. Trying 18 out, 20 out, 22 out, 24 out, etc and back again to see what I like as a compromise.