Square Taper Cranks vs. Splined Cranks.


If you’re just starting out getting into riding one wheelers, then to you, a crank might be a crank. However, there are some fine differences in the types of cranks out there and, considering how you ride and where, it might make a difference in the overall toughness of the unicycle you ride. 

The two main types of cranks commonly available today are square taper cranks and splined cranks; splined cranks contain a subset of cranks known as ISIS cranks. The construction of each of these types of cranks impacts the durability of the connection of the crank arm to the hub axle of the unicycle.

Square taper cranks, which are also known as cotterless cranks, have a square cross section that fits into a correspondingly square receptacle in the hub axle. The connection of the crankset to the axle is completed with a nut or bolt. In order to provide a secure fit, the hub axle receptacle and the crankset need to fit tightly together; it is friction that enables the rider to transfer the rotational force from the pedals through the crankset into the hub and drive the wheel. 

Because the cross section of these cranksets has four corners (they’re “square” taper spindles), a lot of force is concentrated at the corners. Therefore, you must never ride a unicycle with cotterless cranks if the cranks are loose. Doing so could result in deformation of either the hub axle or the cranks themselves. If this happens you’ll never be able to get a secure fit again. 

By contrast, splined cranks and ISIS cranks have several splines or “teeth” along the taper of the crank, that fit into corresponding recesses in hubaxles designed to receive them. They have more than four “corners,” and larger diameter spindles, which makes them much more durable and provides a better, more secure fit than can be achieved with square taper cranks

Because of their structural integrity, splined cranks, specifically ISIS cranks, have become the standard for unicycle cranks and are common on mountain unicycles, freestyle unicycles, and even road unicycles. There are two things you must be aware of, however. One is that splined cranks are not interchangeable; two unicycles with splined cranks may require very different cranksets. The other is that you need to ensure you install and tighten the cranksets on the proper side of the axle. Riding a unicycle with the splined cranks on the wrong sides will cause irreparable damage.

Are you looking for more information on the difference between square tapers, ISIS and other types of splined cranksets? Perhaps you’d like to find new cranks for your unicycle and want to be sure you’re getting the right model. You can find unicycle cranksets for sale, along with valuable resources on installation and replacement right at Unicycle.com. 

Visit their website today and pick yourself up a new crankset for your favorite ride; they even have the bolts, spacers, wrenches, and other tools you’ll need to complete the job. Check out their collection and if you can’t find what you need on your own, just call them at 678-494-4962.


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