Been ignoring crank length? Find your perfect fit now for a more comfortable ride!

Crank length, the distance from the center of the bottom bracket axle to the center of the pedal axle, is a critical yet often overlooked aspect of a bicycle's setup.

Longer cranks provide greater leverage, making those grueling climbs feel a bit more manageable, as you can generate more power with each turn of the pedals.

However, this increased leverage can come at a cost. If the cranks are too long, you might find your knees and hips complaining after a long ride, the extended range of motion putting extra strain on your joints.

Shorter cranks can lead to a higher cadence, allowing for a smoother, more efficient pedaling motion.

Shorter cranks reduce the range of motion required, making each pedal stroke easier and less taxing on your muscles and joints, especially over long distances.

But why is crank length so often overlooked? Many people attribute their cycling discomfort—be it hip pain, lower back pain, or general fatigue—to poor riding posture or inadequate muscle strength, especially in the core.

They might adjust their saddle, tweak their handlebars, or invest in strength training, all the while ignoring the possibility that their crank length could be the culprit.

So, what crank length do most bike manufacturers use? Typically, bikes come with crank lengths ranging from 165mm to 175mm. But does this standard fit everyone?

Generally, taller riders with longer legs might benefit from longer cranks, while shorter riders might find shorter cranks more comfortable and efficient.

For instance, a rider with a height of 6 feet or more might prefer a crank length of 175mm, whereas a rider closer to 5 feet might find a 165mm crank more suitable.

One size doesn't fit all—data is just a guideline. Crank length varies from person to person. Next, Tesway will help you find the crank length that fits you best.

At Tesway, we understand the importance of getting the crank length just right. Our electric bikes come equipped with cranks that have been meticulously tested and adjusted to achieve the optimal length for a variety of riders.With

Tesway, you can rest assured that every aspect of your ride has been fine-tuned for the best possible experience.

With Tesway, you can rest assured that every aspect of your ride has been fine-tuned for the best possible experience.

Why You Should Calculate the Proper Crank Length

Power and Efficiency

Crank length plays a significant role in determining the leverage a rider can apply to the pedals.

Longer cranks provide greater leverage, which can be advantageous in certain situations, such as climbing steep hills or sprinting.

This increased leverage means that for every rotation of the crank, the rider can generate more torque, which translates to more power delivered to the bike's wheels.

However, this increased leverage can also lead to higher strain on the rider's muscles and joints, potentially causing fatigue and discomfort over long rides.

Shorter cranks can result in a higher cadence, promoting a smoother and more efficient pedaling motion.

A higher cadence reduces the muscular strain per pedal stroke, allowing for sustained energy output over extended periods.

This is particularly beneficial for endurance riding and long-distance cycling events, where maintaining consistent power output with minimal fatigue is crucial.

Comfort and Fit

Cranks that are too long can cause discomfort and even injury, especially to the knees and hips, due to the increased range of motion required for each pedal stroke.

This can lead to overuse injuries and strain on the joints, particularly in cyclists who ride frequently or cover long distances.

Cranks that are too short may not allow for optimal power transfer and can lead to inefficient pedaling.

Shorter cranks reduce the range of motion, which can be more comfortable for riders with limited flexibility or those recovering from injuries.

Properly fitting cranks contribute to a more natural and comfortable riding position, reducing the risk of long-term discomfort or injury, and enhancing overall cycling enjoyment.

Cadence and Pedaling Dynamics

Crank length directly affects cadence, the rate at which a rider pedals. Shorter cranks enable a higher cadence, which can lead to a smoother and more fluid pedaling motion.

This is particularly advantageous for time trials and triathlons, where maintaining a high cadence is essential for performance.

High cadence riding helps to distribute the workload more evenly across the leg muscles, reducing the likelihood of localized fatigue.

Longer cranks can slow down the pedaling rate but may provide more torque, beneficial for sprinting or power-based activities. This lower cadence, high torque approach can be advantageous in scenarios requiring sudden bursts of speed or power, such as track cycling or criterium races. However, the increased force required per pedal stroke can be taxing on the muscles and joints over time.

SEE ALSO Does E-Bike Tire Size Really Matter

More Studies!

Numerous scientific studies have explored the impact of crank length on cycling performance. 

Journal of Applied Physiology Study

A study published in the Journal of Applied Physiology examined the influence of crank length on power output.

Researchers tested crank lengths ranging from 120mm to 220mm, involving 16 well-trained cyclists.

The results indicated that there was no significant difference in maximal power output across the different crank lengths. The mean power output varied only slightly:

• 120mm cranks: 1147 watts
• 170mm cranks (standard length): 1152 watts
• 220mm cranks: 1140 watts

These findings suggest that cyclists can achieve similar power output regardless of crank length, supporting the notion that crank length may not drastically affect overall performance. 

International Journal of Sports Medicine Study

Another significant study from the International Journal of Sports Medicine focused on the impact of crank length on knee joint loading.

The research involved 12 cyclists using crank lengths of 145mm, 170mm, and 195mm, with detailed analysis of knee joint forces through motion capture and force sensors. The study found that:

• 145mm cranks: Reduced knee joint forces by approximately 10%
• 170mm cranks: Standard forces used as baseline
• 195mm cranks: Increased knee joint forces by approximately 12%

Shorter cranks could indeed reduce the stress on knee joints, potentially lowering the risk of knee injuries. These findings underscore the importance of considering individual biomechanics and comfort when selecting crank length.

Medicine & Science in Sports & Exercise Study

A study published in Medicine & Science in Sports & Exercise investigated the effects of crank length on cycling economy and muscle activation.

The study involved 10 competitive cyclists using crank lengths of 150mm, 165mm, 170mm, and 180mm, measuring oxygen consumption and electromyography (EMG) signals of major leg muscles. Key findings included:

• Oxygen consumption: No significant difference between crank lengths, indicating similar metabolic efficiency.
• Muscle activation: Shorter cranks (150mm) showed a slight increase in quadriceps and hamstring activation compared to longer cranks (180mm), which had higher calf muscle activation.

These results suggest that while metabolic efficiency remains unchanged, different crank lengths can alter muscle activation patterns, potentially affecting rider comfort and fatigue.

Crank Length Formulas

Finding the right crank length can significantly enhance your cycling performance and comfort. Here are two effective methods to calculate the crank length that suits you best, both supported by scienti

Method 1: Tibia Length Method

According to a study by Martin, James, and Spirduso, measuring the tibia length can provide a more accurate crank length recommendation than inseam length.

The tibia length is measured from the center of the ankle bone to the center of the knee joint. This method suggests that the optimal crank length is approximately 41% of your tibia length.

Step-by-Step Calculation

1. Measure Your Tibia Length

   • Sit
   • Measure the distance from the center of your ankle bone to the center of your knee joint in centimeters.

Apply the Formula

$$\text{Crank Length} = \text{Tibia Length} \times 0.41$$

For example, if your tibia length is 40 cm:

Crank Length=40×0.41=16.4 cm≈164 mm

This calculation suggests that a crank length of approximately 164 mm would be ideal for you.

Method 2: Inseam Length Method

Another commonly used method is based on your inseam length. This method provides a general guideline that works well for many riders.

Step-by-Step Calculation

1. Measure Your Inseam Length

   • Stand with your back against a wall and your feet about 6 inches apart.
   • Place a book or similar object between your legs, pushing up lightly until it touches your crotch.
   • Measure from the floor to the top of the book in centimeters. This measurement is your inseam length.

2. Apply the Formula

   A widely accepted formula to determine optimal crank length is based on your inseam measurement:

   $$\text{Crank Length} = \text{Inseam} \times 0.216$$

   For example, if your inseam is 80 cm:

   $$\text{Crank Length} = 80 \times 0.216 = 17.28 \text{ cm} \approx 172.8 \text{ mm}$$

   This calculation suggests that a crank length of approximately 172.8 mm would be ideal for you.

Adjust and Test

While these formulas provide a solid starting point, it's essential to adjust and test the crank length to suit your personal preferences and riding style. Here's how:

• Test Rides: After installing cranks of the calculated length, take your bike for several test rides. Pay attention to how your knees, hips, and overall body feel during and after the ride.
• Fine-tuning: Make small adjustments if needed. If you feel discomfort or strain, try cranks that are 2.5mm longer or shorter and see if it improves your riding experience.

Conclusion

Crank length can be both confusing and fascinating, yet it's crucial for optimal cycling performance. We hope this article has brought some clarity to the topic.

Current cranks offer a limited range of lengths, which doesn't fully cater to the diverse range of riders.

Proposals suggest that 155mm and 165mm cranks should become the new standard sizes.

Decreasing crank length generally provides more benefits compared to increasing it.

However, small adjustments of 2.5mm usually aren't significant enough to make a noticeable difference. On the other hand, changes of 10mm can have substantial and impactful effects on fit and comfort.

There are various methods to determine the best crank length, but the most effective approach considers knee and hip angles, riding style, and a bit of trial and error.

FAQs

What are the standard crank lengths used by most bike manufacturers?

Most bike manufacturers offer cranks ranging from 165mm to 175mm. However, these standard lengths may not fit all riders perfectly, which is why personalized adjustments can be beneficial.

Are there significant benefits to adjusting my crank length?

Yes, adjusting your crank length can lead to significant improvements in riding comfort and efficiency. While small adjustments of 2.5mm might not make a noticeable difference, changes of 10mm can have substantial impacts on fit and performance.

Why are shorter cranks becoming more popular?

Shorter cranks are gaining popularity because they allow for higher cadences, which can improve pedaling efficiency and reduce joint strain. They are particularly beneficial for riders who experience discomfort with longer cranks or who prefer a faster pedaling rhythm.