Why Shorter Cranks May Be Worth the Upgrade

Earlier this year, I had a bike for my mountain bike. It's something I wouldn't normally do for an MTB. Some interesting insights came out of it, and I wanted to share my experience with our audience. Obsessing over small details is something I specialize in.  

When considering mountain bike upgrades, crank arms are some of the lowest on the list. I get it; new shiny suspension or wireless drivetrains are more fun. After specking my bike with higher-rise bars and a shorter stem, I laughed at the thought of cutting down my bars 20mm when my bike came specked with a 170mm crank arm, and I haven't thought twice about it. You'll rotate your crank arms a billion times over the lifespan of your bike. This planted the seed to begin my journey into finding the perfect crank arm length (for me), and it was pretty straightforward. Recently, shorter cranks have been gaining popularity among mountain bikers. In this article, we'll explore why upgrading to shorter mountain bike cranks might be a decision worth considering, as well as my experience when downsizing.

Understanding Crank Length & 5DEV

Before diving into the benefits of shorter cranks, it's essential to understand what crank length is and how it affects your riding. The crank length is the distance between the center of the bottom bracket and the center of the pedal axle. Standard crank lengths for mountain bikes typically range from 170mm to 175mm, depending on frame size. More companies have been making crank arms that range from 135mm to 175mm with everything in between. Specifically, a company called 5DEV. You may have seen their riders making a big splash in the DH racing scene this year on the Frameworks Factory Team. 5DEV has been making boujee mtb bits out of San Diego, CA, using high-precision CNC machines that significantly increase the durability and lifetime of their products. 5DEV is a division of 5th Axis, a world leader in manufacturing complex components for the aerospace and medical industries. If it's good enough for NASA, it's good enough for me.

How do you know your crank length size?

Finding your optimal crank length is a trial and error-process. However, there are tools that can make it easier to get started. 5DEV makes the "Crank Length Device" that can give you a quick base number to try. You can also go to a professional bike fitter who could give you a precise number. A DIY method you can also try is holding the textbook between your legs while in your MTB kit. Then, measure the distance from your crotch to the bottom of your shoes using a metric measuring tool. Then, to know your recommended crank length, you must get out of your calculator. Take that number, and you'll get 20% of that. Multiply that number by 0.20, and you can use that number as a base for crank length. For XC and Road, use the closest number to your measurement. Most companies will recommend sizing down 5 mm to 10 mm for trail and enduro bikes, depending on preference. This can give you a good starting point for crank lengths to test out and find the perfect fit. Helpful video link 

Benefits of Shorter Cranks

• Improved Pedal Clearance

One of the most immediate benefits of shorter cranks is improved pedal clearance. Mountain biking often involves pedaling through rocky terrain, roots, and sharp ledges. We've had a pedal strike that's halted a techy climb or tossed you over the bars on a sketchy descent. Shorter cranks reduce the likelihood of pedal strikes, allowing you to clear obstacles more efficiently and maintain momentum. This can be particularly advantageous in technical trail sections where precision and control are crucial.

• Enhanced Cadence and Efficiency

Shorter cranks can lead to a higher pedaling cadence, improving overall efficiency. A higher cadence reduces the strain on your muscles by distributing the workload more evenly and allowing for smoother, more fluid pedal strokes. This can be especially beneficial during long rides or climbs, where sustained power output is necessary. A common thought is "you have less leverage when pedaling," which is true, but when elite pro cyclists like Tadj Pocacar are using 165mm cranks on their road bikes during this year's Giro d'Italia, there is clearly something there.

• Better Joint Health

Mountain biking places significant stress on the knees and hips. Crank length can play a role in mitigating this stress. Shorter cranks can reduce the range of motion required by your knees, potentially lowering the risk of injury and discomfort. Short-term cranks can be a wise choice for riders with a history of knee problems or hip pain who want to prevent future issues.

• Improved Riding Position

Your bike's geometry and riding position are critical for comfort and performance. Shorter cranks can help you achieve a more optimal riding position by allowing for a higher saddle height without compromising your pedal reach. This can enhance your control over the bike and provide better leverage during climbs and descents. Shorter cranks can also give the bike a more maneuverable feel. You can feel the difference on big enduro bikes with slack headtube angles.

Considerations Before Upgrading

While shorter cranks offer many benefits, it's essential to consider a few factors before making the switch:

• Personal Preference and Riding Style: The ideal crank length can vary based on your riding style, physical dimensions, and personal preference. Testing different lengths to find what feels most comfortable and efficient for you is a good idea.
• Bike Fit: Ensure your bike's fit is adjusted correctly to accommodate the new crank length. This may involve minor tweaks to your saddle height and position.
• Gearing: If significantly changing your crank arm length, you may also want to size down your chain ring. This will prevent you from spinning out.
• Cost: Upgrading your cranks can be a significant investment. Weigh the potential benefits against the cost to determine if it's a worthwhile upgrade for your riding needs.

Conclusion

In the ever-evolving world of mountain biking, every component plays a role in your performance and enjoyment on the saddle. An endless array of companies want you to shell out your hard-earned cash on useless bike components, but shorter crank arms are here to stay. This blog is not an ad; I paid for all these cranks. That said, I am very impressed with the quality and attention to detail of 5DEV components. Shorter cranks offer several compelling advantages, from improved pedal clearance and efficiency to better knee health and increased maneuverability.

So, the next time you're out on the trail, consider whether switching to shorter cranks is the upgrade that takes your riding to the next level.

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