Sunday, December 11, 2005

The Bouncing Bits: Tuning Fork

This is going to be the last installment of "Bouncing Bits" and it deals with the basic set up and fine tuning of todays front suspension forks.

As stated in previous posts, the most basic forks only have a pre-load setting that can be adjusted. (Well, okay- some don't even have that!) The pre-load is usually used to counteract the weight of the rider so that proper sag can be achieved. Sag is the term used to describe the amount that the stanchions slide into the sliders when the rider mounts the bike. Sag adjustment is based off the recommendation of the fork manufacturer.

Another common adjustment found on a little nicer fork would be rebound adjustment. This basically is an adjustment that affects the speed at which your fork will extend back to it's riding height after compressing from a trail obstacle or other input. Faster rebound for stutter bumps or continuous trail obstacles. Slower rebound for buff trail and gravity compression sections, or g-outs, as they are commonly referred to as. Of course, this is only a generalization of how you might use the rebound control. Be creative!

Very nice forks might have a compression adjustment. It will allow you to fine tune the way in which your fork "puts out the fire!" Maybe your favorite trail has a way of making your fork feel very stiff. Maybe back off the setting. Blowing through your travel on hard braking downhill? Add in some more compression damping. The term damping is used to describe the action that occurs when your fork tries to cancel out an occillation caused by a trail obstacle, or other input. The actual hardware developed to do that job is commonly referred to as a damper.

Finally, a very modern fork will probably have some sort of platform damping. Remember, damping is used to help cancel out an occillation. So, the occillation that platform damping is trying to cancel out is you! That's right! Have you ever gotten out of the saddle to power over a hill only to find that when you did this, it made your suspension fork bob up and down like a pogo stick? That's the type of input platform damping was made for! It feels stiff when pushed on from the handlebars, but still activates when the tire hits a trail obstacle. This feature is usually tuned to rider taste. Of course the ultimate canceling out of rider input is the lockout which, as the name implies, locks out the suspension aspect of your fork all together. Most often, there is a little lever mounted on the handlebar to activate/ de-activate the lockout feature.

Other than complicated tear downs and oil viscosity swaps, these are the most common features of todays suspension forks. (Negative springs not withstanding which can affect preload, compression, and rebound, all at the same time!) Anyway, remember, if you get a fork that is tunable in some way, make sure you read your fork manual, and experiment! That way, you'll know what best works for you.

I hope you found this series usefull. Much of what was discussed can also be applied to rear suspension, also. Just experiment, and it will all begin to take hold. Have fun and go ride your bike!

No comments: