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| Term |
Definition |
| Brake Bosses |
Brake bosses are where you mount v-brakes (or the old cantilever brakes) to the bike. If you are using v-brakes and looking for a new frame or forks, check that the one you want has brake bosses as some frames / forks now only have disk brake mounts. |
| Compression Damping |
Compression damping controls the speed at which a suspension system will compress when a bump is hit by the wheel. More damping results in slower movement. Over large bumps, setting lots of compression damping will prevent the suspension from "blowing through" its travel quickly, often giving the rider more control. But it will make the suspension feel "harder" to the rider over small bumps. There is no single correct setting for compression damping as it depends on personal preference, style of riding and the type of terrain encountered. |
| Crown |
The crown of a fork is the bit that connects the fork legs and the steerer tube together. Crowns are usually forged as this makes them very strong. Some are machined out of solid billets of aluminium, which is more expensive but lighter. Legs and steerer tubes can be either bonded, cold pressed or bolted in. See the definition for Stanchions for more on the various methods. |
| Disk Brake Mounts |
Disk brakes do not attach to forks and frames using the standard v-brake bosses. Instead, many forks and frames come with two small studs on the left hand side that accept bolts for disk brakes. NOTE: not all disk brake manufacturers use studs at the same spacing. While the "International Standard" mount is becoming popular, some brakes use the "Hayes" standard. Make sure your brakes and bike are compatible before you buy! |
| Dropouts |
This does not refer to tattooed downhillers who found sixth grade too tough. Dropouts are the little metal tabs on your frame and fork that keep your wheels where they should be.
There are several kinds of dropouts available at the moment. Standard dropouts are found on most cross country bikes and forks. QR20 dropouts and RockShox Tulio dropouts, which are much bigger and heavier than standard dropouts and therefore stronger, may be appropriate for the downhill and freeriding crowd. Forks, Hubs and Skewes designed for one system will not be compatible with any other.
Whenever you put your wheels back on a bike, always check the quick release skewers are seated properly in the dropouts and done up tightly. If you ever spin a wheel and it rubs hard against a brake block, check that the skewer is properly seated in the dropout before adjusting the brakes. It's quite easy to get the standard ones in slightly squint. |
| Front Mech |
See Front Derailleur. |
| Lockout |
Lockout causes a suspension system to go rigid and act like a normal "unsprung" bike.
Lockout is useful in two ways: first, it prevents the suspension from "bobbing" when a rider is pedaling on flat road or uphill; and second, it reduces the height of suspension forks (on some models) which has benefits for riding uphill.
Bobbing is regarded as inefficient and annoying, although good design and changes in riding style have made this less of a problem than it was.
Most suspension forks are quite long and when riding up a steep slope, this causes the rider's weight to be a long way back on the bike. Consequently, it is very easy to lift the front wheel off the ground with a powerful stroke, leading to "wandering" steering and interrupting the rider.
Not all suspension forks get shorter when locked out, but if you can find one that does, you will probably find lockout to be a very useful feature. |
| Preload |
Preload is the control that adjusts the amount of sag in a suspension system (front or rear). Preload is adjustable on even the cheapest equipment and is usually achieved by altering the amount of air in the positive air chamber of an air sprung system, or winding on / off the preload ring that compresses the spring on a coil sprung system. |
| Rear Derailleur |
The rear derailleur is the strange parallel linkage containing springs and wheels at the back of the bike that is used to change gear. It changes gears by derailing the chain from one sprocked onto another, hence the name.
Forcing the chain sideways off one sprocket onto another is not very sophisticated, but years of refinement have made this work suprisingly well.
The difference between derailleurs is in the amount of machining to the sprockets, the quality of bearings, the weight of materials, and the length of the cage. Short light derailleurs made of high quality materials / bearings combined with carefully machined sprockets offer the best performance for general riding. |
| Rear Mech |
See Rear Derailleur |
| Rebound Damping |
Rebound damping controls how quickly a suspension system returns to normal after being compressed by a bump.
Generally, rebound should be as quick as possible (to prepare for the next bump) without being so fast that it "kicks back" the rider. If you find you are being thrown off the bike by the suspension extending too fast after a big hit, then you do not have enough rebound damping set. If you find the suspension "packs down" and does not have time to return to normal extension on stutter bumps, then you probably have too much rebound damping set. |
| Sag |
Sag is the degree to which a shock absorber compresses with the rider sitting motionless on the bike in a normal riding position. Usually, this should be between 15% and 25% of available travel for cross country riding and slightly more for downhill riding.
Sag allows the suspension system to extend when it comes to a dip in the trail. If it had no sag and did not extend, the wheel would not follow the dip, which results in decreased traction, especially on bends. Sag is controlled by the amount of preload set. |
| Seals |
Seals keep the lubricating agent (usually oil or grease) in the moving parts of your bike and the dust and grime out.
The worst thing that you can posibly do to a sealed component (such as bottom bracket, hub or suspension fork) is to use a powerfull hose to clean it, as this tends to force water through the seals, pushing out the lubrication and promoting corrosion. |
| Sliders |
Sliders are the parts of a suspension fork that slide up and down the stanchions smoothing out bumps in the trail. Sliders are joined by a bridge and the steering ability of the fork is often determined by the stiffness of the bridge / sliders assembly. Sliders and bridges are often made of cast alloys, such as magnesium, for their light weight and stiffness. |
| Stanchions |
Stanchions are the upper portion of suspension fork legs, which are rigidly connected to the fork crown and stay still as the lower portion (sliders) move up and down absorbing bumps in the terrain. Stanchions are made from chromed steel (heavy but strong and friction free) or aluminium (coated with Teflon or some other material to prevent friction). Stanchions are either cold press fitted into the crowns, bonded or held in place by bolts. Of these options, bolts are the best as they allow replacement of a stanchion if damaged, then cold press fitting as it is light and strong. Bonding has not been very sucessful and most manufacturers have abandoned this method. |
| Steerer Tube |
The steerer tube is the tube on the front forks that sticks up from the fork crown, through the head tube of the bicycle and then joins to the stem. Historically, steerer tubes were threaded to accept a quill but now almost all are threadless to fit the popular "Ahead" system. Aluminium is the most popular material for steerer tubes, though some riders may opt for steel if they are very heavy on their bike, or are limited by budget. |
| Travel |
Travel is the maximum amount of movement that a suspension system is capable of. Currently, this ranges from about 2" at the short end of the scale up to 10" at the long travel end.
How much travel you need depends on the type of riding that you do. It is generally accepted that 2-3" is best for cross country racing, 3-5" is good for general trail riding, 4-8" is considered within the ballpark for serious "fro" or "north shore" freeriding, and anything over 6" is suitable for downhill.
Several types of suspension fork offer on-the-fly adjustment of travel which is very useful if your riding style and terrain is diverse. Other forks can be altered by disassembling them at home and moving internal spacers. This is not quite as convenient as on-the-fly adjustment but at least your travel will suit your ride. |
