Pedal Power and The Importance of Crank Arms on Recumbent Trikes

Welcome back to another Utah Trikes article. Recently we’ve gotten a couple questions asking about why having the correct crank length on your pedals is important so we thought in this article we would go through why crank length is important, how it affects your ride, and how to change your crank length. Let's get into it!

What is Crank Length?

what does a crank arm do besides connect your trikes pedals to the gearing? Well Cranks can be one of the most important parts of your trike. Their main function is that they allow for the power put into the pedals by your legs to move the gearing, utilizing the leverage created by the pedals distance from the center of the crank which is what we call crank length.

Crank length is the distance between the center of the bottom bracket and the center of the pedal axis. Which is basically just the distance between the pedal and the center of the front gearing.

There is a variety of crank lengths but the most common ones available are between the 170 to 175 range but there are also cranks that are in the range of 165 and 180 mm.

Why is Crank Length important?

Now you are probably wondering how much just a couple millimeters of a crank arm could influence your ride anyways. And the answer is just a little bit of extra or too little length of your pedals can over extend your muscles and start to cause pain.

When you are looking for a trike and you’re being measured, you are going to be positioned so you are sitting comfortably and the length of the boom is adjusted so your pedal at maximum extension will be just short of having your leg fully extended. You’re doing this for two reasons, you are getting as much power possible from each stroke of the leg. Two, by not having your leg fully extended it reduces the chance that your feet may slip off the pedal.

Also by having a fully extended leg you will be locking your knee in each stroke which will cause you to become tired sooner and could result in injury.

once you've been sized to your trike and you may find that your rides can be uncomfortable and sometimes it’s a little difficult to walk after the ride because your knee is bothering you or your hips are sore.

So why is this happening? Its because most bike part manufacturers just go with the standard crank lengths. Because there are so many sizes of people its a lot simpler to stick with an average length.

Finding the right crank length is a little tricky to determine and takes a little bit of time and some dedication on the part of the rider. If you're going for the most performance enhancing adjustments it will be a lot of tinkering to get your trike adjusted just right, but for the average rider who's looking for a little extra comfort you'll be adjusting your crank arm length and then your x seam to fit properly.

So now that we know why crank arms need to be adjusted to fit the rider. How do you know when your trike needs that crank arm upgrade?

So now that we know why crank arms need to be adjusted to fit the rider. How do you know when your trike needs that crank arm upgrade?

How do I know if changing crank lengths will be beneficial?

If you are feeling pain in your knees this is usually the cause of too harsh of a knee angle caused by longer crankarms. If you have a harder time bending your knees a longer crank arm will bring your knees up to a harsher angle. When you adjust the crank length to be shorter the angle is much less harsh and easier on the knees.

If you find that your knees are not staying straight for the full stroke of the pedal then you are probably compensating for your legs coming too close to your body and adjusting yourself for immediate comfort only to create a different problem.

If your hips are sore then you are probably compensating for improper crank arm length by rocking side to side. This could be for a variety of reasons, but the most common issue would be that with longer cranks you might not be able to extend your leg fully, or deliver enough power to keep your cadence up

In response you may be shifting from side to side to compensate and meet the full extension of your crank arms. If you are noticing these kinds of things while riding, then shorter crank arms may be the solution or at least part of the solution to reduce stress on key hinging points on your body like the knees and hips. A benefit of shorter crank arms is it can help prevent “Pedal Steering”. Pedal steering is usually caused from mashing your pedals or in other words all of your power is only going in the downward stroke. This can lead to over exerting yourself to get the right power output, and general discomfort.

You can prevent this by having a properly fitted crank arm length, or If you have a way to strap your feet to the pedals like clipless pedals and bicycle shoes then you will also gain a more even power output on the downward stroke and upward stroke, as well as a more seamless stroke for the entire rotation.

Pedal mashing and its effects are much more likely with longer crank arms as you are trying to relieve stress and pressure on your leg that is on the upward swing by either knocking/shooting your knees out and away from the body to alleviate your gut so you can breathe easier. To relieve this pressure on the upward leg you rock your hips to send power to the extended leg thus mashing the pedal on a downward strike. All of this causes an imbalance on the trike (not to mention the body) and can create a swaying sensation (pedal steering) as you pedal.

While it is true that you are not getting the same amount of force or torque per individual stroke of the pedal as you would with longer cranks compared to shorter, but you might actually get an overall better power output in the long run. You are able to keep your legs aligned properly and get more continual motion by having your feet slightly closer in the pedal rotation.This can also be applied outside of comfort and more in the realm of the type of riding style you are trying to achieve. For most people crank arm length doesn't make a huge difference on your ability to ride, but it can influence how comfortable your ride is for the type of riding you are doing.

If you are a racing oriented rider longer crankarms are going to influence your ride more than shorter crank arms. The length of the crankarms allows for more leverage on your pedals which will make keeping a consistent speed easier to achieve with a lower cadence.

You will also have slightly more bend in your knees which can deliver a higher physical power input giving you more speed with a consistently lower cadence. Taking more effort to push the crank but letting you get more out of it. But as mentioned in the last section larger crank arms will cause more stress to be placed on you knees and hips to achieve this higher power output, but if your main goal is go fast a more intense workout is expected.

If you are more of a casual rider a shorter crank length could be the better option for you. Shorter crank arms decrease the amount of torque needed to make a full pedal revolution and are great for changing pace.

When you pedal with shorter crank arms your pedal revolutions will be shorter and maybe feel a little off at first as you get used to it. But they are easy to adapt to with their low muscle demand. Whichever size cranks you go for, it's important to note that it can feel a little strange at first and you just have to go on a couple rides to fully get used to the new crank style. With all of this crank arm info you may be wondering if there is an easier way to get different crank arms, or you aren't needing crank arms for a specific performance style at all and are just trying to get a trike that fits you properly beyond a usual trike's limitations.

For that we have a solution and that is our Revolution Crankarm shortners. This is a crankarm addition that we designed here at Utah Trikes in Springville Utah. Its function is to give you a simple way to make your crank arms shorter without having to buy all new crank arms. These crank arm shorteners are great too because they have multiple points of adjustment. So if you're experimenting with what crank length is right for you you have the room to try out 4 different adjustments to see what's right.

It's also great If you have multiple riders that will be using your trike that are slightly different heights. Shorter crankarms can also substitute for a shorter boom to a point, so if you and your trike partner have slightly different heights these shorteners are great for a quick versatile boom adjustment alternative without having to adjust your chain. And even for single riders with miss matched leg lengths you are able to adjust each pedal at different distances to make up for the difference between pedal reach. But the biggest uses our customers find for these shorteners is to shorten a boom past its limits. A boom can only go so short even when we cut it down to be even shorter than standard. But sometimes for a particularly small rider it still isn't short enough for them to pedal comfortably, so the crank arm shorteners are great for shortening that boom just enough to make sure our rider can have an ideal riding experience. This is also really helpful because some cranksets don't allow for crank arm swapping. Most commonly the FSA Gossamer crankset found on the Catrike models.

The Revolution Crankarm shorteners have adjustment settings of 19.05 millimeters to 41.275 millimeters. That's an adjustment range of 22.225 millimeters giving you the equivalent of a 143 millimeter crank arm on its lowest setting with the standard Catrike Crankset. Farther than you could go with any standard crank arm adjustment to accommodate for an even wider range of people. The crankarm is a part of a trike that is often overlooked, but can make a big difference in your comfortability and maybe even be something that you've been missing this whole time.

Crankarm adjustments are fairly simple but it's important to note that on adjustment when your crankarms become shorter it can alter your pedaling and power output similarly to if you adjusted your front gearing. For example every 10 millimeter your Crank Arm is adjusted shorter; it's the equivalent of going 2 teeth bigger on your front ring. This is why some riders may find it harder to get up steep hills and have to shift down with shorter cranks more often.

Now many of us out there are riding for the exercise benefits as well as being able to enjoy time outdoors. If you are not able to enjoy your ride or your time is limited because of discomfort in the knees, hips, or breathing, changing the crank arm length may be beneficial to your time on and off the trike. This adjustment can help with recovery time due to better body alignment.

Here at Utah Trikes we offer a wide variety of crank arms from 152 to 175mm. As well as our Revolution crank arm shorteners. For most people a small adjustment of around 2.5 mm won’t do much but a change of around 10mm will definitely do it for you.
Having a crank length that’s right for you can make a big difference when riding. You can take unneeded pressure off of your legs and be more worried about having a good time than your body hurting.

While it may take some time in the beginning to figure out what crank length is right for you and if you should change crank lengths it’s worth it in the end. Not only will you be able to have a more comfortable ride but you’ll see improvements in speed and a better fit on your trike.

Thank you so much for reading! If you want to stay up to date with all things trikes make sure to bookmark our article page so you don't miss our newest articles. If you have any personal experience with crank arm adjustments consider leaving a comment down below and let us know we would love to hear about your experience.

With that remember to relax spin fast and ride trikes.