Posted on: Friday, January 4th, 2008 at 5:19 pm by: Terra L. Fletcher
Properly adjusted bike suspension will protect the rider from the roughness of diverse terrain. It also improves safety and efficiency because it allows a more balanced trajectory of the rider’s mass over uneven ground. Suspension can be implemented at the front fork, the seat post, the rear, and even the saddle or hubs. There are four primary areas of suspension: preload, sag, compression, and rebound.
Bike terms: Preload
Preload allows you to adjust the spring weight based on your body weight. Spring weight is the amount of force required to get the spring moving. Heavier rider equals higher preload. If you have air fork or shock, preload is adjusted by pumping air into it. Check your owner’s manual for pressure/weight guidelines. A coil sprung bike uses controls to compress the spring. Zero preload exists when adjuster knobs are turned completely counterclockwise.
Bike terms: Sag
Sag refers to the amount your saddle moves from your sitting on it. The rougher you ride, the more sag you will need to cushion the bumps. To set front sag, set your preload to zero. Have a friend and a pen. Mount the bike and rock gently to sag. Stop. Have your friend mark on the fork’s stanchion where it hits the top seal. If you race cross country, you’ll need 12%, and for downhill, 30%. Most of us need 20% of the distance of travel. If the distance is greater, increase preload. If distance is less, let air out or consider swapping for a less stiff coil spring. Hint: You want the lowest amount of preload to achieve proper sag. Too many turns of preload affects fork performance. Setting rear sag is done much the same way. Both should take you little time and few tools. Ideally, though, set sag when you purchase your bike. Qualified mechanics can do it fast, and this is the best time to decide whether you want different springs.
Bike terms: Compression
Compression is the time it takes for your suspension to slow downward force. You will need to experiment. Counterclockwise to open, clockwise to adjust. Too much compression and it will take too long, too little and you will bottom out on the slightest change in terrain.
Bike terms: Rebound
Rebound is just what it implies: the time it takes to return from full travel after compression. Rebound should be easily adjusted by clearly marked controls on your bike. If rebound is too slow, you won’t be ready for the next bump. If it is too fast, your bike suspension will feel too springy.
It is well worth the time and effort you will spend to get your suspension just right. You will be riding on a cloud, and your backside will thank you.