The Downhill bike (Explained)

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The Downhill bike (Explained)

Post by Admin on Fri Mar 13, 2009 1:45 pm

The Downhill bike (Explained)

http://www.mtb-freeride.com/ride/freeride_explained/dhbike.asp



A downhill bike will have most of the following characteristics:

Long travel full suspension frame:



i.e. about 6-8 inches of travel. The frame will be beefed up to make it stronger than a normal bike with gusseting (extra metal plates incorporated into the frame during manufacture).

The geometry will be different to incorporate the suspension movement and are usually shorter in length for better handling.

The shock will connect the rear wheel via a swing arm or linkage to the shock, usually a coil over type shock (a spring over the shock body containing the damping mechanisms) the other end will be connected to the main frame.

This is known as a single pivot or a linkage frame design respectively, this ensures that the suspension works at all times, without too much rider, pedal or braking induced bob.

A long travel suspension fork:


These normally have about 6 inches of travel and are of the triple clamp verity. Meaning the legs are held together by three clamps / crowns, however itís only two as the third is the hub. Triple clamps are generally laterally stiffer giving better steering and braking, however this is not always the case.

Some single crown forks can be better than some lesser quality triple clamps. The springs are inside the legs, as is the damping mechanism, most forks have adjustable damping for rebound and compression.

Downhill specific build up including:

Disc brakes:



They giving improved stopping power in all conditions with out damaging the rim through braking action. Plus you can still ride a buckled wheel, within reason.

Bars and stem:


Long strong bars, to improve control and shorter stem to give the correct rider cockpit position.

The saddle should have strong rails and a non-slippy surface.

Single chain ring and chain device:


Less of a range of gears are needed for downhill, so a single chain ring is used. The chain device stops the chain from bouncing of the chain ring.

Wheels and tires


Wider stronger rims and fat tire with aggressive tread patterns improve grip. Tire choice is extremely important and can win or lose a race. Thicker tubes are used which enable lower pressures to be run therefore giving more tread to ground = more grip.


A downhill bike is obviously different from a cross country bike in many ways, but the less obvious things are important to. Such as:

Head angle:



A slacker head angle slows down the steering allowing the bike to be more stable at speed. It also allows for the riders natural position, when the bike is positioned on a slope.

Weight: A downhill bike feels reassuringly heavy due to the fact that every thing is over engineered for strength. When you first ride a decent full-susser it feels slow and unresponsive, but put a turn of speed and a few trail obstacles in itís path and it will come to life.

Youíll never go back to your twitchy hard tail again. Well not for a while anyway.

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