Shock spring length question

[markgoodrich]

My aftermarket shock "relaxed" spring length is 168mm. Installed length, using manual adjuster, is now 152.5mm. From there I can crank in more using the hydraulic adjuster. My question: is it normal to have this much reduction in the spring length to get proper sag?

[Quinn]

Sounds like you need to add more fried food. Sorry, couldn't resist.

 

 

[Selden]

What is your definition of "proper" sag? 15mm difference doesn't sound like much to me, but it all depends on the spring rate. Rule of thumb would be to aim for static sag 35% of total travel (possibly more if you have short legs) with 0 turns on the hydraulic adjuster.

[ShovelStrokeEd]

15mm of preload on that short a spring sounds to be a lot to me but I'm not sure enough about the rate of the standard spring or what your weight is.

 

When Jim Lindemann ordered my Ohlins shock for my Sprint, he asked the distributor what the factory spring rate and preload was. He then specified the next up rate on the spring and much less (factory was 20mm new was 5mm) preload. Turns out to have been perfect on my bike for me. I run no hydraulic preload when solo and about 1.5 turns with 120 odd lbs of luggage aboard. The ride is just amazing. Felt a hair stiff at first but one click less compression damping fixed that. Cushy ride with no bad movement either solo or loaded.

[markgoodrich]

What is your definition of "proper" sag? 15mm difference doesn't sound like much to me, but it all depends on the spring rate. Rule of thumb would be to aim for static sag 35% of total travel (possibly more if you have short legs) with 0 turns on the hydraulic adjuster.

 

Good question; 30% is what I think we went for when we installed the shock; took 6 turns on the preload adjuster (which blew a seal 9000 miles later), leaving only 3 turns for two-up and fully loaded. The ride was miles better, but when the seal blew, the supplier added in the manual preload when he installed the new adjuster, giving the measurements I mentioned. My question, really, should have been "is the spring the right one, or should I go through the considerable brain damage to get a more appropriate one?" As I said, I was a happy boy until the seal on the preload adjuster blew. Now I'll be riding with no additional preload when solo, with all ten turns available to tune the ride for when my wife and all our stuff is aboard.

 

Ed, to answer your question, I weight about 220 with all my gear on (the gear is really, really heavy. No, really!)

 

Thanks for the answers, guys.