We can tweak many things on our bikes; one of the most debated elements is crank lengths. Some cyclists feel best riding with short, crank arms, while others prefer longer ones. But why is this? The answer lies in how crank length affects comfort power and your peddling style. Everybody's different, so there is no universal standard for every cyclist. So in this blog, we will go into the details of what is the best crank length for cycling? 

Crank length is the distance between the centre of the pedal axle and the bottom bracket spindle. In other words, it's how long each crank arm is from the pedal hole to the crank arm bolt. The most common sizes range from 165 mm to 175 mm for road bikes. However, mountain bikers often ride with crank lengths of 170 mm and 175 mm or even as short as 165 mm. So which one is best? Well, it all depends on how you like your peddling to feel and your body's proportions. 

Every time you push your pedal with your foot, it makes a circle. Longer crank arms create a large circle, while shorter cranks make a smaller one The larger the circle, the more torque you have, but it requires a wider range of motion. On the other hand, a smaller circle reduces your range of motion, which can help your cadence and reduce hip and ankle strain. Often, cyclists prefer shorter cranks as they help them spin faster. However, longer cranks are beneficial during steep climbs. 
 
What feels "right" often comes down to biomechanics, flexibility, and muscle strength. That's why professional bike fitters pay close attention to crank length. When you get it right, comfort and efficiency line up nicely. 

• Promotes quicker cadence with less knee and hip flexion
• Favoured by riders with shorter legs or flexibility concerns
• Reduces the "dead spot" at the top of the pedal stroke

• A common default for many road bikes
• Balances torque and cadence for a wide range of riders
• Suitable for those who want a middle-ground option 

• A popular length on many standard road bikes
• Suits average-height cyclists with typical leg lengths
• Offers a mix of leverage and pedalling fluidity 

• Increases leverage, which can feel helpful on steep climbs
• Requires more knee and hip movement per stroke
• Often chosen by taller cyclists with longer inseams
• Might strain joints if your flexibility or leg length is limited 

When choosing crank length, your inseam measurement is incredibly important. Taller cyclists may prefer longer cranks, but those with shorter inseam measurements may find them cumbersome or uncomfortable. You can use your inseam as a guide for sizing your cranks, but it is often better to try different lengths to see which feels better. 

Your riding style and discipline make a difference to crank length. Generally, mountain bikers ride with shorter cranks, especially on technical terrain. This gives them extra clearance when riding over rocks and roots. However, if you race on the track, you may prefer a length that will optimise speed and torque. Road cyclists often prioritise cadence comfort and aerodynamics. 

How you pedal can make a difference in which crank length to go for. For example, do you like to spin high RPMs or stay on the big gears? Shorter cranks can make high-cadence peddling easier, while longer cranks benefit riders who prefer to use brute force. Experimenting with different crank lengths can give you an idea of your natural peddling style. 

The length of your crank makes a difference in how your knees and hips bend. When your bike has longer cranks, there is more flexion at the top of each pedal stroke. On the contrary, shorter cranks reduce that bend, which can help you if you have joint issues. Therefore, you could try riding with shorter cranks if you have recurring knee pain. 

Rotor Bike Components designs innovative cranksets with modular concepts. Our crank arms come in various lengths and materials. Most models allow you to pair them with different spindles and chainrings. You can mix and match to suit road, gravel, or mountain bike setups. 
Here's a quick rundown of some notable Rotor crank arms: 

• Often used for road cycling, with lengths typically ranging from 165 mm to 175 mm.
• The arms are CNC-machined aluminium, offering strength without excessive weight.
• Pairs well with Rotor's direct mount chainrings or traditional spider setups.

• Lightweight carbon construction for reduced mass.
• Similar length options are available to the aluminium ALDHU line.
• Can be used for road, gravel, or cyclocross with appropriate chainrings. 

• Shares modular features with ALDHU, letting you swap spindles easily.
• Often found with length choices around the 170–175 mm range.
• Provides a sturdy, cost-effective alternative to premium carbon arms.

• Tailored for mountain biking, with robust arms that handle off-road stress.
• Crank lengths often include 165 mm or 170 mm to enhance pedal clearance.
• Typically pairs with Rotor's MTB-specific chainrings for single or double setups. 

• The carbon version of the KAPIC series, shedding weight without sacrificing strength.
• Offers high stiffness for explosive MTB efforts.
• Maintains the same modular approach for ring combinations. 

1. Start with Your Height and Inseam: See where you fit in typical ranges (e.g., 170–175 mm for average heights).
2. Consider Your Ride Discipline: Road or gravel riders might lean toward 170–175 mm. MTB riders may choose 165–170 mm for clearance.
3. Think About Your Style: Do you prefer high-cadence spinning or grinding big gears? Shorter cranks help spinning, and longer cranks assist leverage.
4. Check Past Crank Experience: If you've experienced knee pain on 175 mm cranks, test 170 mm. If you feel under-geared on climbs, maybe try 172.5 mm or 175 mm.
5. Aim for Versatility: Rotor's modular cranks let you change arms without replacing everything. Start with one length, then adjust if needed. 

Crank length is a personal choice shaped by body size, flexibility, and riding styles. Rotor Bike offers plenty of crank length options, from short 165 mm to longer 175 mm or more. They also come in different materials, such as aluminium or carbon, to match your budget. 
 
Choosing your crank length involves considering cadence, joint health, and overall comfort. Don't be afraid to experiment with different crank lengths, but do it thoughtfully. A subtle change can enhance pedalling smoothness or reduce discomfort. Ultimately, the "best" crank length is the one that feels natural and supports your style.

Check out our range of cranks in our online store. 

#Happy riding ROTORian