Aftermarket fork lockouts

Kowalski675

Ouija wrote:

bennett_346 wrote:

I understand the stuff about preload not affecting stiffness or spring rate, but what i've always wondered is why does it matter to adjust preload if all it does is adjust how far down into the travel the fork sits?

Surely if you buy 160mm forks for example you want as much of that to be useable travel as you can?

Because you don't want the fork to only compress (when going over a raised bump, for instance). You also want it to expand a little when the front wheel encounters a pot hole (you want the fork to expand down into the hole so that there's no sag and then return to it's slightly compressed/sag position as it comes back up the other side of the pot hole). It won't be able to do this if you've got the forks at maximum extension all the time (it'll be only able to compress). Instead, the whole front of the bike will go down into the pot hole rather than just the fork expanding down into it and leaving the handle bars at the same height. Hence the reason you ride around with the forks a little sagged (so that they're unidirectional and not monodirection).

Which is a longer way of saying that you need sag so your suspension doesn't top out. Although, admittedly, possibly better, if he doesn't understand the terminology. But I think you meant bidirectional

The Rookie

bennett_346 wrote:

That's a well explained answer, i understand now thanks. Since i've never had coil forks it's something i've always wondered but never thought about it hard enough to ask or research.

It's the same with air forks.....

Greer_

The Beginner wrote:

bennett_346 wrote:

That's a well explained answer, i understand now thanks. Since i've never had coil forks it's something i've always wondered but never thought about it hard enough to ask or research.

It's the same with air forks.....

This is actually interesting! Next question:

If its the same for air forks, how do you change the spring rate of an air fork? As putting in air sets sag, and rebound sets damping characteristics (how quickly/slowly the fork returns). Is it to do with the compression damping?

It's hard to get your head around it, as putting in more air seemingly stiffens the fork up, but does the spring rate remain the same?

supersonic

Spring rate of an air fork is directly proportional to sag. So more air = higher spring rate = less sag.

Greer_

Ahh so its not the same as coil forks then - makes more sense that the spring rate changes.

bennett_346

The Beginner wrote:

bennett_346 wrote:

That's a well explained answer, i understand now thanks. Since i've never had coil forks it's something i've always wondered but never thought about it hard enough to ask or research.

It's the same with air forks.....

It can't be, the sag is set to determine the spring rate not ride height surely?

supersonic

It is to set both: with a coil the spring rate can only be changed by changing the coil - but you can set ride height independantly with the preload adjuster (ie sag). There are subtle differences.

The Rookie

You can change spring rate on an air fork but decreasing (increasing not an option) the volume of the pressurised air can. you get plastic inserts for shocks, but their are ways of doing it with forks as well, for example I could run an SPV valve in my Manitous giving me volume adjust.

Bennet, the sag is by definition the ride height, at which point you end up with the spring rate you end up with, you then run more or less sag if you want to change the spring rate!