Rear shock preload - Glenn has it figured out

[bchatt]

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

Try setting your race (rider) sag 1st. You should aim for a rider sag of 100-110. That should result in a static sag of around 25-30 if the spring is correct for your weight. These are pretty much tried and true figures that should get most modern bikes in the ball park. Don't necessarily worry about how much preload that needs.
I weigh 75kg and get these results with a 4.8 spring, which I replaced the stock 5.2 with.
Remember, if your spring is too soft you will have less static sag than 25-30 for the race sag of 100-110, if your spring is too hard you will have more static sag for the race sag of 100-110.

As a side note my sachs shock blew apart at 50 hrs - I noticed it get all sproingy then within minutes the circlip blew out of the body. It was repaired under warranty with a newly designed seal head and has been brilliant ever since - now about 250 hours.