Understanding Ohlin adjustments

[flm842]

My new-to-me 06 GS came equipped with Ohlin shocks which the former owner told me that he had left at "normal setting." He seemed to indicate that he had installed them and was satisfied with their base setting but that I could read the literature and adjust them for myself. This guy rode solo, same as me. He weighed about 210, I weigh about 250.

My problem is that I don't have enough time on the bike to have a feeling for shock performance and that I'm stupid. I read the Ohlin literature twice and simply could not get my head around it how to adjust these things correctly.

Is there a simple explanation for setting these things? I'm just a few days away from a long trip.

[marc]

You need a way way to hold the bike steady with you on it as normally ridden, i.e. in your riding gear without adding or removing any extra load. A buddy to stabilize the bike helps. You also need a way to do some measurements, perhaps a second buddy. It can be done alone if you have something like a wheel chock.

The goal is this... to set the "ride sag" of the bike to a certain percentage of the total suspension travel. Then you set the damping. The specs say the rear end has 200 mm of travel. The experts say the rear ride sag should be about 30% of that, or 60 mm. How you get there is to first put the bike on the center stand with the rear wheel off the ground. Measure from the axle tube to any arbitrary point directly above the axle. The top or the bottom of the R1200GS decal is handy on our bike. Write that measurement down.

Then you take the bike off the center stand and have buddy #1 hold the bike steady while you sit in the saddle with your gear and your feet on the pegs. Buddy #2 needs to repeat the measurement you did. The difference between the two measurements is your "ride sag". If it is less than 60 mm your spring didn't compress very much... back off the pre-load. If it is more than 60 mm your spring compressed too much, add pre load. I you can't get the desired sag regardless of pre-load settings the spring is not correct for your ride weight.

Once the sag is set you want to adjust the damping. The goal is allow the spring to return to its starting position after compressing without overshooting. Have one of your buddies hold the bike steady. Push down on the rear of the bike, compressing the spring. Let go. What did you see?

If the rear end rises slowly the bike is over damped. If you hit a series of bumps with an over damped bike the spring will not have time to get to its starting point when you hit the second bump, in effect adding pre load. It gets worse for the third bump. Eventually you run out of all spring travel.

If the rear end rises quickly and overshoots its starting point the bike is under damped. Hit a series of bumps and the bike will start acting like a pogo stick. Worse case the rear will actually bounce off the ground.

When you push down on the rear end then let go you want the bike to quickly return to its starting point without any extra bounce. Once you have it that way you're ready for the final adjustments.

What? Yes, the above only sets a starting point for test rides. The procedure is to ride, make a small adjustment, then ride some more. Repeat until you are happy with the results. Then do the same thing for the front

[flm842]

Marc. Well thanks for taking the time to make your post. I read it through and the light is starting to turn on. I had a buddy take a look and together we think we can sort these adjustments out. What's even better is that Im starting to understand the why and wherefore.

I'll post back after we've gone through this process and let you know the outcome. Thanks again.

[pdxrmccgs]

Sounds like you want to dig into chassis tuning.

*Race Techs Motorcycle Suspension Bible.*

An excellent book well worth the 35 bucks IMHO. I think I got mine at Amazon.

http://www.racetech.com/page.aspx?id=90