Square taper cranks are so common on modern unicycles that some sources list them as “standard,” and they certainly are common, but what exactly are they, and why?
Also known as cotterless cranks, square taper cranks have a tapered end that is square in cross-section. This tapered end corresponds to a hub axle that has a square receptacle.
These square cranks are tapered so as to be forced into the square hub axle and pushed in until a friction fit has been achieved. Once they are forced into the hub axle they can be secured with a bolt or a nut, holding them in place.
The square crankset cannot rotate within the hub axle, enabling the rider to transfer power from the cranksets into the wheel, powering the unicycle.
The reason they are so common is twofold – it is a basic design and it is easy (and economical) to manufacture. Because they are relatively affordable and simple, many unicycles, specifically beginner and affordable unicycles, have them.
They’re also perfectly useful for most riders, as long as you observe a few common points.
Before Riding with Square Taper Cranks
The most important thing you have to keep in mind if you have a unicycle with square taper cranks is that you must never ride a unicycle with cotterless cranks if the cranksets are loose or improperly secured.
Any interplay – no matter how slight – between the square taper and the hub axle will place an immense amount of torsional stress on both. In extreme cases, the hub axle’s resistance on the taper can distort or round the angles of the cranksets, enabling it to rotate within the axle.
If this happens, your cranksets (or your hub axle or both) will be permanently damaged, irreparable, and will need to be replaced. Simply ensure that your cranksets are properly secured before riding, and you should be able to avoid this problem.
Also, keep in mind that while cotterless cranks are great for learning and freestyle, they’re not necessarily the best option out there for advanced tricks and mountain unicycle riding.
Are There Better Options?
While square taper or cotterless cranks are common among many unicycles, there are stronger options out there known as splined cranksets.
In cross-section, instead of having four 90 degree corners, making a square, splined cranks have a series of “teeth” that fit into a corresponding hub axle. One popular version of splined cranks is known as an ISIS crank, which stands for International Spline Interface Standard.
Splined cranks like ISIS cranks are stronger before there is a greater total surface area of contact in the interface between the hub axle and the end of the crankset. They are better able to tolerate the rigors of mountainous terrain or trial riding, for example.
One thing you must be aware of with ISIS cranks is that they can require more maintenance than square taper cranks and must never be installed on the wrong side of the unicycle. Doing so, like riding with loose cotterless cranks, will destroy them.
Where Can I Get Square Taper Crank Sets?
Interested in getting a new, compatible pair of square taper cranks for your current unicycle? Have questions about sizing, compatibility, or other features? Check out Unicycle.com.
Unicycle.com carries a wide range of unicycle crank arms and pedals for replacement or upgrades, in an equally wide range of sizes and configurations. Before you make a repair or replacement, get in touch with their customer service team for assistance.
They can be reached on their website, Unicycle.com, via live chat, or by phone at 678-494-4962