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Condensed Answer: Theoretically, downhill bikes can be used uphill, but their geometry, weight, and lack of low gears make them very inefficient climbers. If climbing is a priority, downhill bikes are not an option.

The Downsides Of Using a Downhill Bike Uphill

• Anti-climbing Geometry

As the name suggests, downhill bikes are engineered to excel at descending on uneven terrain rather than climbing it. As with other machinery, form always follows function.

The properties that render a downhill bike good at descending make it a poor climber.

The first issue would be the extra slack head tube angle.

The head tube angle is the angle formed by the head tube and the ground. A slacker head tube angle positions the front wheel further in front of the rider. This geometry allows the wheel to pass over large obstacles with greater ease while reducing the chance of going over the handlebars.

The slack head tube angle, however, requires a slacker seat tube angle. Or in other words, the seat has to be repositioned closer to the rear wheel. As a result, the rider is more upright. The upright position increases drag because the rider’s torso acts as a sail.

• Weight

Downhill bikes are the heaviest mountain bikes of all for the following reasons:

a. Full-suspension (the front and rear shock add additional weight)

b. Overbuilt Frame

Downhill bikes use double-crown forks with lots of travel that heavily stress the head tube.

Consequently, the frames of downhill bikes are reinforced to the maximum. The extra material adds weight to the bike.

c, Overbuilt components

To avoid failure, all downhill components (cranks, rims, hubs, axles…etc.) are maximally thick and strong. The robustness comes at the expense of extra weight.

• High Gearing

Downhill bikes come with 7-10 speeds consisting of mid and high gears. The absence of low gears makes pedaling uphill an unpleasant experience.

The table below contains the gearing of popular downhill bikes:

Conclusions:

• Most downhill bikes have 7 speeds.
• The lowest gear/cog has about 25 teeth.
• The front chainring is of medium size.

In different, trail bikes often have 10-12 gears with a very large cog at the back with at least 32 teeth. A larger cog makes it easier to climb because the rear wheel rotates less per one revolution of the cranks.

Of course, the user can install a 12-speed cassette with lower gears on a downhill bike too, but the change will not compensate for the rest of the drawbacks that downhill bikes have during ascents.

• Soft Suspension

Suspension eats pedaling energy. Hence why full-suspension bikes are so slow on the street. Every time the rider spins the cranks, some of the pedaling effort is absorbed by the compressing suspension.

Technically, some suspension models have a lockout function designed to fix this problem, but those are usually found on XC bikes which are better climbers, to begin with.

Pure downhill suspension rarely has locking capabilities because the bike isn’t designed for riding around the block as efficiently as possible anyway.

• Uncomfortable Seat Angle

The seat of downhill bikes positions the rider behind the pedals and makes for inefficient pedaling. Hence why riders often get out of the saddle when they want to power through an incline.

This effect is amplified to a larger degree when the rider elevates the saddle to a position allowing full knee extension. In some cases, it feels as if you’re about to fall behind the rear tire.

• Low Bottom Bracket

Downhill bikes have a lower bottom bracket than trail bikes. The purpose of this engineering is to lower the center of mass and increase the bike’s stability.

A lower bottom bracket increases the potential of the so-called pedal strike (the pedals hitting the ground when pedaling in a turn).

On a downhill bike used as such pedal strikes aren’t a big issue because the rider isn’t pedaling much to begin with. There are downhill descents done even without a chain. However, a downhill bike that’s going to be used as a multi-machine will display this problem more frequently.

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If the goal is to have a bike that’s decent at descending but also capable at the park and uphill, a better choice would be to get a trail bike with a single-crown fork.

Trail bikes have less suspension travel, higher gearing, and a more comfortable pedaling position. Of course, an enduro bike isn’t as fast as a dedicated downhill bike when descending on off-road terrain, but it doesn’t fall that far behind while remaining capable on other fronts.

Summary: What You Need To Know

A downhill bike makes for a poor climbing experience for the following reasons:

• Non-efficient upright position
• The seat is positioned too far back and makes for inefficient and uncomfortable pedaling
• The suspension of the bike is tuned for descending and eats a lot of pedaling power.
• The bicycle is heavy and positions a lot of the rider’s weight over the rear wheel.

Ultimately, a downhill bike isn’t designed for climbing. Even a small incline could make for a poor experience. Hence why downhill bikers rely on lifts to get up a hill.

If a rider wants a bicycle that can descend while remaining capable on a climb, a better choice would be to get an aggressive hardtail or an enduro bike.