Types of Cranksets and Crank Length: A Short (but Helpful) Guide

Types of Cranksets and Crank Length: A Short (but Helpful) Guide

11/09/20

Whether you’re simply looking for more information on the types or cranks that come with, or can be used with, unicycles or you simply want to learn more about the unique features and strengths of each place, you’re in the right place.

It might not be the best-understood subject in the world of unicycling, but we pride ourselves on being the first source our clients come to when they need to learn something new. It’s the same reason you can lean on our team of experts to teach you more about the impact of tire size and width on how a unicycle will handle.

But tire size and width aren’t the only things affecting your control over your unicycle. Cranksets play a part in maneuvering and handling a unicycle, and among the several types that exist, there are some unique features that make them desirable (or undesirable) given the situation.

Things that Matter: Cranksets

Just in case you are a beginner in this, it would help to know what we are going to address. A crank or a crankset, which is also sometimes known as a chainset where there is a chain drive involved, is the part of the unicycle to which the pedals and the wheel are attached. It is the portion of the machine that connects and translates the force from the rider’s legs into the rotational energy that the unicycle requires to move. See the picture at the right for a visual representation of cranks. With this high-level view, you might be starting to get an impression of just how important the cranks are; like the tire and the rim of a unicycle, the cranks must be able to handle a lot of force and are therefore one of the most important components of a unicycle.

Types of Cranks

There are a few types of cranks that are fairly common in unicycles made today, and among them are the cotterless cranks (or square taper cranks), ISIS cranks, and splined cranks on which this article will focus, along with a few more.

Cotterless Cranks - A.K.A. Square Taper Cranks

Cotterless cranks are also known as square taper cranks and are very common in modern unicycles, particularly in some of the more affordable models produced today. The reason for their prevalence is twofold; they are affordable to produce, and they are relatively easy to install.

Cotterless cranks have tapered ends that are square in cross-section (hence square taper crank) that are fit over the hub axle (which should also be square) and then secured with a not or a bolt. These types of cranks can afford a fairly quick, snug fit, but care must be exercised when riding a unicycle with these types of cranks.

If these cranks become loose while riding, the immense force placed on the squared angles of the corners can cause them to become deformed. If that happens, you will never be able to fit square tapers in the slot again. This amounts to irreparable damage to the unicycle and a safety concern as well.

Installation

To remove or install square taper cranks, you will need a crank extractor as well as a socket wrench or an Allen wrench. First, you will need to remove the dust cap if there is one. Then, unscrew the nut or bolt that holds the crank arms on the hub.

Insert the outside threaded portion of the extractor inside the crank, making sure the threads are seated correctly. Turn the handle on the extractor to remove the cranks, and then unthread the tool from the crank to separate them.

To replace them or install new cotterless cranks, first make sure that you are using the proper crank on each side of the unicycle (right-hand crank on the right side, left hand on left). Then, seat the square opening of the crank over the axle and push it into place, then lock it into place with the bolt or nut before replacing the dust cover over the cap.

ISIS Cranks

ISIS cranks are a type of splined cranks, which means that they have little teeth or protrusions from the end of the hub. These types of cranks are more expensive to produce than square taper cranks, but they also form a very sure fit against the hub and are very durable. This makes them useful in situations where there will be a lot of stress and force placed on the axle. These types of cranks are similar to cotterless cranks in that they are pressed to fit over the axle and they also require a crank extractor to remove or replace them.

Installation

To install or replace ISIS cranks, you will also need a crank extractor as you would with cotterless cranks. Something to keep in mind here is that some crank extractors have interchangeable heads so that they can be used with both of these types of cranks. However, it is important to use only compatible parts.

First, remove the crank bolt from the center of the crank arm with the use of a fitting wrench. Insert a crank puller into the internal threads, making sure that the threads are seating properly and that you have a tight fit. Using a fitting wrench, remove the crank extractor and crank from the unicycle.

Splined Cranks

Splined cranks are like ISIS cranks in that they have little teeth to provide a better fit to the axle; the main difference here is that they do not press onto the axle in order to achieve a good fit. Like ISIS cranks, they are much more durable than cotterless cranks, and when properly maintained and tightened stand up well to stress. Some use a bolt to keep the crank arm on whereas others use a series of washers and shims. These types of splined cranks need to be tightened periodically to prevent them from becoming loose. If you ride a unicycle with splined cranks make sure that you never ride them if they are loose, and never install the cranks on the wrong side of the axle.

Installation

Installing splined cranks other than ISIS cranks can be a bit less straightforward because there is more than one style. If you are looking at removing or replacing the splined crank arms on your unicycle but you are not sure how to proceed, please contact us.

Cottered Cranks

There are no new unicycles produced with cottered cranks, which are held in place via a combination of friction and a cotter pin. If you have a unicycle that has cottered cranks, see below for how to remove them. Just be careful when you do so.

Installation

To remove cottered cranks, first, unscrew the bolt on the end of the cotter pin and then gently tap it to back it outwards. You can use a mallet for this but we advise against using one with a metal head because you can damage the cotter pin or even bend it, which will make it almost impossible to remove.

When you replace cottered cranks you should also replace the cotter pin if you can find a compatible unit. Again, as mentioned above, make sure that you install the right crank on the right side and the left crank on the left side before proceeding with the replacement.

Crank Length by Discipline

In addition to the fact that the type of crank fitting can impact the strength and durability of the crank arm, the length can also affect its fitness to a situation. While unicycles may come with cranks ready to go, you might find, personally, that cranks of different lengths suit you better, given your measurements and your pursuits. Take a look below to learn more about some common disciplines and what crank lengths are appropriate.

Freestyle Unicycling

Freestyle unicycling is a form of indoor unicycling that is performed for competition, and as such, riders may need to exercise a precise degree of control over the unicycle. With that said, freestyle unicycles come in a bunch of sizes and configurations. Theoretically, any unicycle could be used for freestyle riding.

However, as a general rule, freestyle riders tend to prefer short cranks as it gives them a lot of control over the unicycle. A lot of strength and experience is required to leverage that control, though, so learners may prefer slightly longer cranks.

Mountain Unicycling

Mountain unicycling, also known as Muni riding, is the sport of riding unicycles on slopes or trails. Consider the situations surrounding mountain unicycle-riding - the rider has to extract every ounce of the mechanical advantage he or she can get from the ‘levers’ of the crank arms. For that reason, it is fairly common for muni riders to prefer unicycles with longer cranks.

Touring Unicycle

Touring, also known as long-distance unicycling, has become more popular in recent years. Unsurprisingly, since the main thing that will impact the speed and efficiency of a unicycle is the wheel diameter, long-distance riders prefer these. Long-distance unicycles are usually outfitted with larger wheels, sometimes in 32-inch or even in 36-inch diameters.

While learners of this type of riding tend to start with longer cranks because they are more forgiving, as a rider develops strength and stamina he or she may gravitate towards shorter cranks. Though they are less forgiving, they also enable the rider to translate greater rotational distance through the circumference of the tire from the diminished rotational distance of the smaller crank arms.

Street Riding Unicycles

Street riders hone their skills with tricks and by adroitly clearing obstacles, effectively the same as street riding as performed with a bicycle. Doing so requires a unicycle that is geared towards allowing the rider to exert a lot of control over it, rather than by being designed for optimum speed and efficiency.

Unsurprisingly, unicycles designed for street riding tend to have smaller wheels and fat tires for better traction. There are a few different lengths of cranks that are suitable for street riders. On the shorter end, the cranks can afford greater control, but on the longer end, they can provide more leverage and power. The rider’s preference, within reason, will dictate the fitness of the size of the cranks. However, if you want to get some more insight into what sizes are fitting and why check our page on crank lengths and suitability.

Giraffe Unicycles

Unlike most other types of unicycles, giraffe unicycles connect their crank arms to the axle of the wheel via a chain. This is because giraffe unicycles are too tall for a rider sitting in the saddle to reach the axle with their legs.

This makes giraffe unicycles inherently more risky to ride; in fact, those that ride them often do for the “stunt value.” Longer cranks give the rider the ability to leverage more power more easily, and shorter cranks afford more control as mentioned elsewhere in this article - for example, the Club 5’ Deluxe Giraffe Unicycle (pictured to the left) comes with cotterless 127mm cranks.

Thinking about Getting into It?

Learning to ride a unicycle will be a challenge, but don’t let the uncertainty of a challenge turn you off to learning something new. While you will need to develop skills you may have never had before, learning to ride a unicycle can make you a better athlete, will afford you a great workout, and will be fun to learn overall. If you want to learn more about some of the unique benefits that come along with tackling the challenge of learning to ride a unicycle, read our blog on Five Great Reasons to Get Yourself a Unicycle.

Reach Out to Us!

Do you still have questions, or you aren’t sure where to start? Get in touch with a member of our team! We’d be more than happy to get a new rider into the sport, and we’re always here to answer your questions.

If you don’t get us via the live chat on our website, give us a call! You can reach us at 678-494-4962.