Wednesday, December 07, 2005

The Bouncing Bits: Dealing With "Fire"

Yesterdays post was pretty much a detailed physical description of the make-up of a front suspension fork. Today I'd like to describe what happens when your fork is "at work", and some of the terminology used to describe it.

I like to think of trail obstacles as "fire". Small little bumps are not very "hot". Not much fire there, so they are easily dealt with. The bigger the obstacle, the "hotter" it is to handle. More obstacles mean more "fire" to deal with. When you're riding rigid, you have to be very carefull in how you deal with all that heat. With the right suspension, you roll right on through- no sweat! So, using that metaphor, let's take a look at what happens when a bicycle equipped with a suspended front fork hits some "fire".

When a front wheel hits a trail obstacle big enough to activate your front shock, the forward velocity and weight of the bike/rider combination combine with that obstacle, (and your tire's pressure, wheel deflection, blah, blah, blah.....can we just keep things on a simple plain here?)
anyway.....that all combines to make the fork compress. In other words, the "fire" is absorbed into the fork where the heat gets dissapated, and you go merrily about your way dodging squirrels and rabbits. Well, you actually have something else going on there at that moment, too.

When the "fire" is out, the fork will want to extend to its original length. This is called rebound. So, we have compression, and rebound. These two actions are controlled by what is inside your fork. This can vary depending upon how old your fork is, and in some cases it may not even be inside your fork! Most of the time it is though. So, what-is-it? You say....What is it? ( One of my favorite songs, sorry!)

Well the main component that helps absorb the fire is some sort of spring. It's also the device that keeps the bike/rider combination from compressing the fork under it's weight. Several things can be utilized as a spring device. Air and coiled steel wire are the most common types of springs in shocks these days. Sometimes an old-skooler can be seen sporting a fork with elastomeric material for a spring. Yeeeeaaaaah! Those guys got The Funk goin' on! The rebound action is usually controlled by something in your fork, too. No rebound control is a bad thing! Think of your front wheel/tire combination in your hand. You drop the wheel/tire combination on the ground. What happens? Your wheel/tire combo goes flipping about wildly all over the place. What we have here is....failure to have rebound control! Some wheels you jus' cain't reach! git wot we had heeyah lass week..........whoops! A movie quote used in another of my favorite songs! need rebound control! Believe it! Things that control rebound in today's forks? Friction, oil, air, and a combination of all three sometimes!

Okay, that is enough silliness for today. Tomorrow we will look some more at "Dealing With "Fire".

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