Do Square Taper Cranks Offer Any Advantages?
If you get serious about personally selecting your preferred one-wheeler by your riding discipline, it won’t be long before you get familiar with cranksets.
Cranksets provide an interface between the pedals (and thus, the rider) and the hub axle of the wheel.
Many unicycles are made with splined cranks, featuring 19mm to 22mm diameter axials which have many teeth that provide a very secure, very strong grip against the hub axle. Some use a special type of splined crank called an ISIS crankset.
However, many more - especially beginner and affordable unicycles - feature a basic type of crankset known as a square taper crank which has a 17mm diameter axial.
Why Square Taper Cranks Are Popular
First, if you’re not familiar with square taper cranks, these are the type of cranks that are square in cross-section. They’re also known as cotterless cranks.
If you remove them from the hub axle of the wheel, you’ll see that they have a square shape - a square taper spindle - when you look at them point-on.
The hub axle that corresponds to square taper cranksets is also square in cross-section. These types of cranksets are easy to install; first, you push them into the hub axle interface until they are snug. This creates a friction fit. Then you secure the cranksets on the wheel with a nut or bolt.
This is one of the advantages of square taper cranks. They are easy to install and can be removed, maintained or replaced easily at home with a few tools like a crank extractor and a socket wrench or an Allen wrench.
However, there is another reason that square taper cranksets are so common, especially on beginner and affordable unicycles. They are relatively easy to produce, as well as inexpensive.
Their low cost and general practicality make them popular, especially on models that are supposed to introduce people to the sport of unicycling.
They also afford a secure grip and are fairly strong. So long as you ensure that they are properly affixed and tightened before riding, they’re suitable for learning, some freestyle riding, and even commuting.
However, it’s important to note that if you ever ride a unicycle that has square taper cranks, and the cranksets are loose in the hub, you risk destroying the unicycle by doing so. If the cranks are loose, you can either deform the crankset or hub axle, which causes irreversible damage.
Another thing is that square taper crank sets, though they are practical for beginner unicycles and select other applications, are not usually seen as strong enough for trials riding, trick trending, or mountain unicycling (Muni riding).
These shortcomings have caused some to develop a preference for another type of crankset, known as a splined crankset.
Alternatives to Square Taper Cranks
If square taper cranks are square in cross section, splined cranks are “toothed,” or more properly “splined.”
This means that they have ridges or “splines” running along the spindle at the end of the crank arm that connects to the hub axle.
Splined cranks, because of their teeth, deliver greater friction between the hub axle and the crank arms. Because of this, there are more points concentrating the sheer stress, distributing it over a greater surface area. This is what enables splined cranks to offer superior strength when compared to square taper crank sets.
They also attach differently. Some Splined cranks affix to the hub axles with a bolt, others through a series of washers and shims. ISIS cranks are a special type of splined crank that, like cotterless (square cranks) can be pressed into the hub axle prior to securing in order to provide a friction fit. These require a crank extractor for removal.
Either way, all forms of splined cranks (including ISIS cranks) must be periodically tightened in order to ensure their security from time to time. They can become loose due to use, and like square taper cranks, if you ever ride a unicycle with loose splined cranks, you can damage the cranks and the hub axle.
It’s also critical to ensure that you only ever install splined cranks on the proper side of the unicycle in order to prevent damage. Riding a unicycle with splined cranks installed on the wrong side can also cause irreversible damage.
Want to Learn More?
So, in a nutshell, square taper cranks are popular because they are relatively easy to install, provide a decent, secure fit, and are fairly affordable to produce, in contrast with ISIS and other splined cranks which are much more expensive.
We carry replacement crank arms, pedals, and unicycle tools. You can check out some of our square taper and splined cranksets via the link above to see if we carry what you need to make a replacement or repair.
You can also contact us directly at 678-494-4962 if you’re not sure what parts you need and we would be happy to help.