Rear shock preload - Glenn has it figured out

[GMP]

Wow, that sounds really off. At one time early last year I peaked at 195 lbs. in shorts, so figure I was close to your weight geared up. Same '07 bike too. My 5.4 spring was set to approx 10mm and worked good. My race sag is about 110mm. Maybe your spring is not really testing at 5.4? Is that 20mm preload what it takes to get the bike to steer or to meet a certain sag number?

[stainlesscycle]

something is just wonky. it's felt low in the back for a while now, ever since i lost damping - 've rebuilt it twice, and it seems 100% but once it gets hot it sucks. i even switched to just air to try hope when it heats up it would stiffen up. maybe my settings are way off. i have the sachs with the 16mm shaft, but it has 12mm i.d. where the valving sits......... just haven't been happy with it for the last month or 2.

what is your spring length when you get 10mm of preload? i may have a 5.2 on there or something goofy. i'm getting a 5.6 from something else to try it out. i'm 190 in street clothes. it's just felt soft in the back to me. like unbalanced..

[Jakobi]

I'm 75kgs in shorts. Around 90-95kgs geared up. Just put a 5.4 Ohlins on the TTX and started at 10mm preload but the static sag came in around 42mm. Added a few more turns by hand to get the static to 35mm. This puts my race sag just over 100 without gear. Haven't measured in gear to confirm yet.

[wence]

Stainless, You have not got the dodgy shock problem that occurred with the 07 sachs shock. Mine had the problem and when it got hot the shock just pogo'd all over the place.Once fixed it was great.
Cheers Mark

By the way my ohlins shock has some numbers that I can't see then 10/52 , so I assume mine is a 5.2? It is yellow by the way.
I currently must be in a good paddock(or just need to drink less and exercise more), but I weigh about 90 kilos(200 pounds), in street clothes.
I think I am up for a new spring??

[stainlesscycle]

Originally Posted by wence

Stainless, You have not got the dodgy shock problem that occurred with the 07 sachs shock. Mine had the problem and when it got hot the shock just pogo'd all over the place.:

that's what mine did - tore into it, changed fluid, etc and it was fixed it seemed. i'll get some sag numbers tomorrow maybe. static is fine, the race sag is way off.

[wence]

There was a seal or something that needed to be replaced as a fix for it. Did you do this?

[GMP]

Does it measure soft as in way too much sag, or does it feel soft as in a possible compression damping problem? If you lost rebound I would expect it to ride high and kick, not what you describe. Sure you got all the air out? I did mine three times to be sure, first time seemed OK at first but there was trapped air.

[stainlesscycle]

it only kicked when it got hot. fluid was bad, reservoir seal was bad (there was a small amount of fluid in res).

i switched to bladder setup.

definitely no air in there. works fine with no spring. when it gets hot it was pogo'ing. doesnt seem so bad now, just seems like it's riding low in the stroke, or maybe i'm just hyper sensitive? it seems like i can throw a leg over it much easier than usual.... what is recommended psi ??

i'll post comparative sag numbers tomorrow

[wence]

Just reset my preload on the shock.
It had 16 mm of preload on it and the sag was:
Unloaded on stand:595
Bike resting on ground:557
Me on it no riding gear:465

This gave me a static sag of 38mm and a rider sag of 130???

I adjusted preload on the shock to 10mm.
Unloaded:595
Bike on ground:550
Me on it as above:460

Giving me a static sag of 45mm and a rider sag of 135mm.

Hmmmm

As I said before, I will take it for a blast tomorrow and see what its like, but I reckon I will be up for a new 5.4 or 5.6.
Anyone got one that will fit??
Cheers Mark

[Jakobi]

Originally Posted by wence

Just reset my preload on the shock.
It had 16 mm of preload on it and the sag was:
Unloaded on stand:595
Bike resting on ground:557
Me on it no riding gear:465

This gave me a static sag of 38mm and a rider sag of 130???

I adjusted preload on the shock to 10mm.
Unloaded:595
Bike on ground:550
Me on it as above:460

Giving me a static sag of 45mm and a rider sag of 135mm.

Hmmmm

As I said before, I will take it for a blast tomorrow and see what its like, but I reckon I will be up for a new 5.4 or 5.6.
Anyone got one that will fit??
Cheers Mark

I've got a 5.4 weight spring on my 888 that I only had one ride on before I bought the TTX. Still planning on running the 888 as a spare. Shame you don't live around the corner or I could have let you borrow that too. I'd offer to post it but might cost more than its worth considering Auspost and the size and weight of the spring.