Off Road Unicycles
Rough Terrain Unicycles
by John Foss
Most commonly called Mountain Unicycling or Muni, this riding style has attracted tons of attention, both from unicyclists and the news media. But we don’t all live near mountains, so Rough Terrain Unicycling is a more accurate name. Anyplace a mountain bike can go, a mountain unicycle can go as well (and sometimes better).
Muni has been the swiftest growing and most popular form of unicycling in recent years. People found that it was not only possible, but loads of fun to ride in the dirt! But it was hard on the equipment. Not only did the bumps take their toll, the relatively narrow street unicycle tires, with their requisite high pressure, did not mix well with dirt and rocks.
So people started customizing their unicycles. This started with the addition of pinned pedals and knobby tires. It then went on to wider tires and wider frames to fit them and brakes. In addition, many unicycle saddle lift handles were developed just for rough terrain unicycling.
But more attention was needed on the heart of the unicycle, the axle/hub assembly. Thanks again to the BMX and mountain bike community, a stronger form of drive train already existed, but not for unicycles. They had to be adapted into a wheel hub. Low-cost unicycles were just never intended for big drops, constant exposure to bumps and rocks, and the incessant hard torque of pedaling on the steep stuff, both up and down. Regular (square-taper) unicycle axles simply broke under the strain.
Finally, in 1999 you could buy the first-ever production unicycle with a splined axle, only available in the U.S. at unicycle.com. Since that first one, hand-built by David Mariner as the DM ATU, many others have come along to provide more variety, lower prices and a wider range of choices!
What's a splined axle and why do I want one?
Basically it’s an axle with a substantially wider diameter and an attachment system (spline-shaped) that provides a much more secure fit to the crank arms. The ends of the axle and holes in the cranks look like little stars or gears. Not only do the cranks stay on better, the whole setup is quite a bit stronger than the old stuff.
The role of unicycle axle cannot be filled by standard bicycle parts, because a unicycle combines the wheel hub and pedal axle into a single unit. So the splined axle was a very big step for unicycling. But the various spline systems are not compatible, so you have to match the cranks to the splines on the axle. ISIS is one system. Profile and Qu-Ax are others.
As mountain unicycling became more popular, more and more designers, builders and engineers started experimenting and making unicycles and parts. Many of these new designs and components made their first appearances here. As a result, there are more choices in the area of mountain unicycles than anywhere else!
How do I choose a rough terrain unicycle?
There are three main factors that will determine how much strength you need:
1. Rider weight
2. Type of terrain it will be ridden on
3. Aggressiveness of rider
To these, add some of the less pragmatic factors:
1. How much are you willing to spend
2. Components and features you want
3. "Cool factor"
There are lots of choices and some are very close equivalents. Some of the main differences:
- Handmade vs. mass-produced frame: There is more inherent quality, craftsmanship and owner pride in a handmade unicycle. They cost more because most are built in small numbers, usually by master frame builders.
- Brakes vs. no brakes: Brakes are mostly used for going downhill. On very steep descents they add a level of control you can’t have without them. On longer, more gradual descents, setting a brake to a constant friction level will save your knees a lot of strain Depending where you live, you might have no need for brakes.
- Fat vs. fatter tire: More air volume in a tire makes it absorb the bumps better and is also better to land on in large drops. Once you ride a 3-inch-wide tire you’ll never want to go back to a narrower one. In general, the wider the tire, the more terrain it can handle. The tradeoff in the wide tires is more weight. If you’re interested in pure speed, watch the weight.
- Splined axle: A splined axle is aimed at the serious rider, one who is going to hit the bumps and drops hard. Different axle brands use different numbers of splines with different shapes, meaning you cannot mix and match crank arms among different splined axle types.
- Crank Arms: Weak cranks will bend if you hop or drop a lot. Steel is generally stronger than aluminum alloys, but this depends more on the design and treatment of the metal in manufacture. Cranks for the splined axles are usually very strong to match the strength of their axles. You need splined cranks for the splined axles, cotterless cranks for cotterless (square taper) axles.
- Pedals: For rougher terrain, riders usually want a lot of grip. When you’re around dirt, mud and water, you want a secure connection to your pedals. Pedals with removable pins are popular, because you can replace them when they get dull. But wear your protection (shin guards or leg armor), because those pedals can be hard on shins and calves!
- Pads: The rougher the terrain or the higher your drops, the more important it is to be protected. There is a wide range of choices for your protection. The important thing is wear something before you need it!
- Helmet: Absolutely essential for any kind of rough terrain. Though head injuries in unicycling are rare, you only get one brain. Use it and wear a helmet.