Rear shocks and tokens please explain

[ashleydwsmith]

I’ve seen a lot of mention about putting tokens in shocks etc.

what do these do and how do they help?

 

[steve_sordy]

They alter the shape of the spring curve. See this:

Bikerumor Suspension Setup Series: Full Series PDF - Free Download!

Last week, we wrapped up our six-part suspension setup series. But, we realize it’s not always practical to hunt down the particular session you need,…

bikerumor.com

It is free and not dodgy. Go to page 16 for the answers you need.

 

[RustyIron]

I’ve seen a lot of mention about putting tokens in shocks etc.

what do these do and how do they help?

Your shock holds the suspension up because it has an "air spring." You have to pump up your shock to accommodate your weight. That's the air spring. It's really just an enclosed cylinder with a piston inside it.

The air spring has interesting qualities. You start with a certain pressure inside. If you compress the air spring a little, the pressure increases a little. If you compress the air spring a lot, the pressure increases a lot. The more you compress it, the more difficult it is to compress. We call this spring "progressive."

Progressivity is important. Just plopping your butt on the saddle will compress your suspension 25%-33%. When you hit a little bump, your suspension will suck it up and maybe compress another 25%. So now you've used up over half your travel on a little bump. If the spring was linear, you might hit a medium bump and blow through all your travel. But the spring is progressive, so it will soak up even the biggest hits without bottoming out.

With me so far? Good.
The addition of tokens increases the progressivity of the air spring. If your sag and damper are set up correctly and you're still bottoming out on the big hits, you might want to add a token to increase the progressiveness of the spring. Beware of falling into the trap of indiscriminately adding tokens because you're hella cool with sick tricks sending the big gnar.

If you're a math geek, it's easy to figure out. The progressiveness of an air spring is a function of the air cylinder volume when fully exended, and the air cylinder volume when fully compressed. When you add a token, it takes up space in the cylinder. The percentage of the volume when the shock is extended is small. The percentage of the volume when the shock is compressed is a lot.