Downhill frames can be categorized according to the suspension type they use, each with its own particularities. There are three basic types of rear suspension: four bar linkage, single pivot and multi-link designs. Four bar linkage designs have a pivot in the chainstay and the shock is bolted to the frame at one end. Single pivot suspension designs allow the rear wheel to pivot around a single point on the frame. Multi-link or virtual pivot designs use a rigid rear triangle that is connected to the frame and shock by two links, allowing for a variable axle path and isolation of pedaling forces. Regardless of the type, modern downhill bikes all perform extremely well. The feel of each design, however, is quite different and every rider will have his or her own preference.
The most common way to size a downhill bike is the horizontal distance between the center of the head tube and the center of the seat tube. This measure is called 'effective top tube length' and sometimes 'horizontal top tube length'. The taller you are, the longer the top tube you'll want. In general, riders more than 5'11" tall ride large downhill frames.
Most manufacturers provide suggested sizing charts, and because models vary so much between categories, we recommend searching for the chart specific to the bike you're interested in. It's important to note that everyone has different riding preferences, so it's best to test out a variety of sizes before making a final decision.
The overall feel of a bike is largely dependent on what material(s) the frame is made of, so this is an important consideration.
Aluminum - Aluminum is light, stiff, and affordable, making it the most commonly used frame material. Because it is so stiff, aluminum bikes are characterized by a slightly rougher ride than those made from chromoly or titanium.
Carbon Fiber -
Carbon fiber is basically very thin strands of carbon that can be twisted and woven together, like cloth. To make carbon fiber take on a permanent shape, it can be layered over a mold, then coated with a stiff resin or plastic. It is among the lightest materials and is commonly used for high-end cross-country and all-mountain bikes. More recently it has found its way into some downhill and freeride frames. Because carbon technology is advancing very quickly, costs are being lowered and durability is increasing.
Chromoly Steel -
Chromoly (a steel alloy) is lighter than high-tensile steel, strong, responsive, and offers a relatively supple ride. However, it is heaver than aluminum, carbon, and titanium.
Material Combinations -
If a frame is made of more than one material, it is usually carbon fiber and a metal - either steel, aluminum, or titanium. Material blends are not common, but constructing various parts of a frame from different materials is (ie - a carbon fiber front triangle with an aluminum swingarm). A frame made out of more than one material can help provide better stiffness, compliance, or damping in specific areas.
Things To Look For When shopping for a new downhill frame, the first thing to consider is your riding style. Needless to say, all riders have a unique approach to piloting their bikes downhill. Some choose to stay close to the ground, pumping and pedaling whenever possible, others take to the air at every available opportunity and many fall somewhere in between. More conservative riders may prefer a frame with a longer wheelbase and chainstays, as this creates a more stable bike at speed that will hug the ground more easily. If your race run usually incorporates a handful of daring gaps, and bike-handling is one of your strengths, then a bike with short chainstays and plenty of room in the cockpit will help you get airborne more often. Finally, most bikes can be set up for any riding style thanks to modern suspension technology's tuneability, so don't feel too constrained by available geometries.
How Much To Spend Dedicated downhill frames range in price from $1700 to over $4000.
Models in the $1700- $2500 range are aluminum designs intended for the weekend warrior looking for value and durability rather than ultimate performance. These models use simple suspension designs like a four bar linkage or single pivot, come with shocks that have limited adjustability and feature slightly more forgiving geometries.
Frames $2500-$3300 range offer the same geometry and shock options as the more expensive versions, but use aluminum tubing. This price range is perfect for experienced riders looking to stay competitive or young shredders who want to step up their game.
Finally, downhill frames costing over $3300 are top of the line bikes, made from either aluminum or carbon fiber. These frames will satisfy the needs of the most competitive racers.
Before buying, be sure to do your research and read product reviews. Reviews are a great way to find out specifics about a particular model, user impressions, and things to watch out for. After you've purchased a product and had enough time to thoroughly test it, we encourage you to leave a review for other people to see when they are researching bikes and parts on the web.