Leverage Ratios?

[ECOdork]

It seems like "leverage ratios" (as they relate to suspension) are the hip thing to talk about these days.

What are the details? Which suspension is the numerator and which the denomenator? If I hear something like 2:1 are we talking 2 units (in/mm) of front to 1 unit (in/mm) of rear or is it the other way around?

[CalEpic]

Has someone been hanging out on the Turner board on MTBR?

If not, the answers to all your questions complete with charts and graphs for the asking.

[mtnbikej]

Originally Posted by texlepomis

It seems like "leverage ratios" (as they relate to suspension) are the hip thing to talk about these days.

What are the details? Which suspension is the numerator and which the denomenator? If I hear something like 2:1 are we talking 2 units (in/mm) of front to 1 unit (in/mm) of rear or is it the other way around?

OK.....I'll bite.

Leverage ratios are related to rear shocks/suspension. For example: Your bike gets 5+" of rear travel. Your rear shock does not compress 5". Usually your shock will compress 2-2.25" So basically your rear wheel moves 2" for each 1" the shock compresses........ 2:1 ratio.

Simple huh?????

mtnbikej

[TURNERob]

Yeah mtnbikej has it right. Say on the Turner 5 Spot the travel is 5" and the shock stroke is 2", so the leverage ratio is 2.5 to 1. You divide the amount of travel by the shock stroke.

[ECOdork]

alright, that seems to make sense.
Thanks guys!

Now I can at least sound like I know what I'm talking about!

[Pho'dUp]

That's good info. But what travel rates? Some suspension designs like my Spec. Enduro have been described as having a falling rate suspension. I've read that's why it's better to have an air shock that is more progressive in its compression. I think the 5-spot is supposed to have a rising rate?

Anyone cue in on this one?

[Ladd Jasper]

Originally Posted by Pho'dUp

That's good info. But what travel rates? Some suspension designs like my Spec. Enduro have been described as having a falling rate suspension. I've read that's why it's better to have an air shock that is more progressive in its compression. I think the 5-spot is supposed to have a rising rate?

Anyone cue in on this one?

I'm no engineer, so in layman's terms:

A shock (or fork) designed with a rising rate will become increasingly harder to compress as it goes through its stroke. Think of using a floor pump with your finger over the valve--easy for the first few inches, but it will ramp up quickly beyond that.

A falling rate will, of course, perform in the opposite manner. The further into its stroke, the easier continued compressing becomes.

A linear rate will remain constant through its entire stroke.

[Skeeter]

A progressive rising rate is the best setup. You want the first portion of travel to be softer to absorb small bumps and rocks and the suspension to get progressively stiffer throughout its travel range so that you dont bottom out doing your 5' hucks.

As far as leverage ratio, an ideal setup would be equal, i.e. 1" suspension travel = 1" shock travel. The closer the ratio the better shock performance you would receive.