Suspension - A Daft Question

loukest

Evening,

Sorry if this is a ridiculous question. Just got a new bike, I'm not new to mountain biking but have not really thought about this before now. I'm trying to set up my rear shock, I was following the instructions in the guide re setting the sag. In short, I measured the movement of the rubber ring from the seal, if it was 16mm on a 160mm travel rear shock then that would be a sag of 10%. When I was measuring the shock, it struck me that the shaft which travels inside the can on compression is not 160mm long. I therefore couldn't work out for the life of me how the shock has 160mm of travel. On the flip side, each leg of the forks measure up to what I was expecting, i.e. 160mm.

Am I missing something really obvious....

Tom

ade555

I'm sure you will get lot more technical answer from someone on here then me but I'm sure is to do with how much the actual rear wheel travel, wheel will move in sort of arch shape so the shock shaft don't have to be that long to achieve that, where front wheel only goes up and down that why you can see long stanchions. Not sure what shock you have but IU'm sure there is plenty video on youtube about rear sag.

Well this is my understanding

ade555

you can see a bit more info in this video how rear travel works

https://www.youtube.com/watch?v=A1dUV6pYztg

Suspension sag

https://www.youtube.com/watch?v=iHtVXIN1kF4

cooldad

The rear stays act as levers, so the wheel might move 160mm, but the shock will move a lot less. Measure the actual travel of the shock and then work out how much travel of that you need for the right sag.

loukest

Thanks for the help all, I think I'm about there with it. I take it the fork is as per my initial assumption as the travel is straight up and down rather than in an arc...?

rockmonkeysc

You want a lot more than 10% sag. Most bikes need at least 20%
I'm running 35% sag on my rear shock but not many bikes can get away with quite that much.