jtown

This is on the rear shock. What's it's purpose?

Scooby Snax

I was told it was for setting the sag.

That is what they said when we tried to adjust it, and the dude looks at me and said "aw man somone didnt put the ring back on"

Or it could be like the extra scews the guys at Broil King put in the BBQ's, no peticular purpose, but to make you wonder what its for.

Scoob

TandemGeek

Yes, it's for setting sag and checking travel. You push it up to where it contacts the shock body and then put your riding weight on the bike. When you get off the bike you measure the distance from the shock body to the O-ring and that's how much sag you're getting from your shock given its settings and your weight. If you notice that the O-ring is all the way back on the shock after a ride that means your shock has bottomed out.

If an O-ring is missing you can temporarily use a zip-tie and/or put a zip-tie on your fork to do the same thing, i.e., to check sag when you're setting up the fork and/or testing to see it it bottoms out after making adjustments. I wouldn't leave the zip tie on for prolonged riding as it is more likely to collect grit and scratch the stanchions.

bac

I always thought that saq was a vertical measurement. Wouldn't the ring travel distance be a different number then? In other words, if the shock/bike specifies a sag setting of 10mm, a 10mm vertical measurement would not equate to 10mm of travel as measured by the ring.

Now I'm confused. Which one is it??? Anyone??? :confused:

TandemGeek

Go read this...
https://www.foxracingshox.com/mountai.../manual15.html

Sag is controlled & measured at the shock. Each shock and fork manufacturer provides guidelines for how much sag their products should have to provide riders with the optimal amount of net shock travel. Having 1/2" of sag on a rear shock or 1" on a fork will equate to an amount of physical bike height adjustment, but it's all measured at the shock and/or fork.

bac

ThanX for straightening that up for me. I wonder why they suggest doing 2 measurements and then doing the math? Would it not be easier (and the same measurement) to just measure the O-Ring movement distance?

ThanX again!!!

TandemGeek

Because the guys who develop this stuff are engineers and the "correct" way is to measure the change in overall shock length (sag) from bolt-to-bolt.

Yes, it is and thankfully guys who actually ride mountain bikes provided feedback to product managers who then forced the engineers to add the O-ring. This makes life just a little easier for the average joe who wants to set up his shock and who doesn't have an spare engineer standing by with a steel rule at 10pm when he gets inspired to tweak his ride.

In defense of the engineers, the O-ring does have the potential to collect grit that will scratch the stanchion which is not a good thing. So, with the engineers in mind, keep your O-ring at the far end of the shock where it won't do any damage and be sure to clean the stanchion and O-ring before sliding it up to check sag.

bac

ThanX again, Livngood!!