Is Your Crank Arm Length Too Long?
LONG CRANKS DON'T LEAD TO INJURY... BODY IMBALANCES DO
While studies seem to be fixated on the length of the femur, tibia and foot, the fact is this: Inflexibility is the variable most likely contributing to the discomfort associated with long cranks. This is especially true if you don't have normal range of motion at the hip, knee and/or ankle. If this is the case, then the length of the bones is the last thing you need to worry about! Instead, you need to investigate the fascia, muscle, tendons and ligaments. These are more likely to affect your pedal stroke.
WHY LONG CRANKS ARE DESIREABLE
For every 2.5mm of increased length, you'll have the opportunity to produce an extra 70-100 watts of sprint power. This is largely due to being limited to the amount of force you can generate versus how quickly the cadence can rise. Since the body can more instantaneously increase pedal pressure/ force than it can spin from X rpm to Y rpm, you will always push more sprint power on a longer crank. This is why Mark Cavendish rides a 165mm on the track and 170mm on the road. If he were to ride a 165mm in the TDF, he will have virtually no shot at the sprint. Guaranteed.
However, if the cranks are too long for a riders' fitness, the cranks will turn too slowly and you'll push yourself away from the pedal instead of drive the pedal downwards. This is why riders on excessively long cranks will stand for light climbs, light accelerations and hard tempos- regardless of the gradient.
WHY IS THERE A TREND TO AVOID LONG CRANKS?
In races or rides where sprinting or acceleration performance isn't absolutely necessary, shorter cranks are better. You'll be able to maintain the same FTP with less muscle fatigue during and after the ride (less DOMS). Since a lot of riders also don't want to spend an extra hour or two a day on stretching, this also adds to the appeal of shorter cranks.
This is why shorter cranks are extremely popular among triathletes. They won't exhaust the muscles of their hips and legs during the bike portion, leaving them fresher for the run. Since running also requires less hamstring flexibility, they simply can't or shouldn't be able to push a long crank. Studies have found that increasing hamstring flexibility reduces running performance, so this isn't the compromise a triathlete should make.
I do want to mention the problem many short crank advocates fall victim to: going shorter, and shorter and shorter. Shorter cranks require a lot less force, so it takes more time to cause an injury. "Time" is the key word. As long as the imbalances aren't addressed, buying a shorter crank only buys more time until the injuries creep back. This leads people on this endless and expensive, counterproductive path...
HOW LONG CRANKS CAN MAKE YOU A BETTER ATHLETE
If you successfully correct all of your imbalances, you'll be able to enjoy the full benefits of a long crank. Training on a crank that pushes your limits will make you a stronger rider both aerobically and anaerobically.
Even if your FTP is the same, it will likely take longer to recover after the effort produced on the long cranks. Since cadences are lower on long cranks, the muscles of the hip, knee and ankle have to put out more force to compensate for the slower leg speed. This means more muscle damage and soreness. This is something to consider based on the ride or race you're planning to do.
This doesn't mean go to a Yoga class. While Yoga effectively targets common problematic areas, it doesn't guarantee that you're focusing exactly on the areas that need to be stretched, and if your technique isn't perfect, the effectiveness of the stretch goes down the drain. Technique is extremely important because otherwise the stretch will target areas that don't need stretching and as a result, create a new imbalance or reinforce one that was already there.
While studies seem to be fixated on the length of the femur, tibia and foot, the fact is this: Inflexibility is the variable most likely contributing to the discomfort associated with long cranks. This is especially true if you don't have normal range of motion at the hip, knee and/or ankle. If this is the case, then the length of the bones is the last thing you need to worry about! Instead, you need to investigate the fascia, muscle, tendons and ligaments. These are more likely to affect your pedal stroke.
"Inflexibility is the variable most likely contributing to the discomfort associated with long cranks."If there's a slight bit of imbalance in any of these structures, this will cause you to compensate and make it difficult to pedal comfortably. If the body wants to or can't resist compensating, injury is inevitable, and if you ignore your imbalances, you will get injured! It's better to act early and prevent an injury versus ignore joint pain until it turns into a full blown injury.
"If you ignore your imbalances, you will get injured!"If you prepare your body for the demands of a long crank, you won't develop an overuse injury- considering that you train correctly (periodization). Before blaming the cranks, I want everyone to question whether the cause of injury was actually due to a lack of corrective exercise training and body awareness.
"If you successfully correct all of your imbalances, you can ride long cranks and enjoy it."If you successfully correct all of your imbalances, you can ride long cranks and enjoy it. The only thing you'll experience on long cranks is muscle soreness and not pain from a developing injury.
WHY LONG CRANKS ARE DESIREABLE
For every 2.5mm of increased length, you'll have the opportunity to produce an extra 70-100 watts of sprint power. This is largely due to being limited to the amount of force you can generate versus how quickly the cadence can rise. Since the body can more instantaneously increase pedal pressure/ force than it can spin from X rpm to Y rpm, you will always push more sprint power on a longer crank. This is why Mark Cavendish rides a 165mm on the track and 170mm on the road. If he were to ride a 165mm in the TDF, he will have virtually no shot at the sprint. Guaranteed.
However, if the cranks are too long for a riders' fitness, the cranks will turn too slowly and you'll push yourself away from the pedal instead of drive the pedal downwards. This is why riders on excessively long cranks will stand for light climbs, light accelerations and hard tempos- regardless of the gradient.
WHY IS THERE A TREND TO AVOID LONG CRANKS?
In races or rides where sprinting or acceleration performance isn't absolutely necessary, shorter cranks are better. You'll be able to maintain the same FTP with less muscle fatigue during and after the ride (less DOMS). Since a lot of riders also don't want to spend an extra hour or two a day on stretching, this also adds to the appeal of shorter cranks.
This is why shorter cranks are extremely popular among triathletes. They won't exhaust the muscles of their hips and legs during the bike portion, leaving them fresher for the run. Since running also requires less hamstring flexibility, they simply can't or shouldn't be able to push a long crank. Studies have found that increasing hamstring flexibility reduces running performance, so this isn't the compromise a triathlete should make.
I do want to mention the problem many short crank advocates fall victim to: going shorter, and shorter and shorter. Shorter cranks require a lot less force, so it takes more time to cause an injury. "Time" is the key word. As long as the imbalances aren't addressed, buying a shorter crank only buys more time until the injuries creep back. This leads people on this endless and expensive, counterproductive path...
HOW LONG CRANKS CAN MAKE YOU A BETTER ATHLETE
If you successfully correct all of your imbalances, you'll be able to enjoy the full benefits of a long crank. Training on a crank that pushes your limits will make you a stronger rider both aerobically and anaerobically.
- Longer cranks tend to result in higher heart rates, so you'll train the accessory muscles (muscles for breathing) more effectively.
- Longer cranks require more force from the muscles that power your pedal stroke, so during high power intervals, they'll adapt to be stronger and more powerful.
- Longer cranks require you to frequently keep your flexibility in check to prevent injury, so you'll feel more accountable to make stretching a part of your routine.
- The larger force exerted on the pedals causes the bike to flex which provides more resistance for the core and muscles of the upper body. A stronger core and upper body leads to better standing and sprinting technique.
Even if your FTP is the same, it will likely take longer to recover after the effort produced on the long cranks. Since cadences are lower on long cranks, the muscles of the hip, knee and ankle have to put out more force to compensate for the slower leg speed. This means more muscle damage and soreness. This is something to consider based on the ride or race you're planning to do.
- If you plan to do multi day races, it would be a good idea to save the longer crank for the last day, unless you have teammates working for you everyday.
- Long cranks are ideal for single day races like criteriums and some road races.
- Avoid long cranks if the race is very long in duration because the legs will be more likely to burnout towards the end of the race.
- Avoid long cranks for tapering. Shorter cranks will let the legs rest completely.
- Avoid long cranks for injury or post op rehabilitation.
This doesn't mean go to a Yoga class. While Yoga effectively targets common problematic areas, it doesn't guarantee that you're focusing exactly on the areas that need to be stretched, and if your technique isn't perfect, the effectiveness of the stretch goes down the drain. Technique is extremely important because otherwise the stretch will target areas that don't need stretching and as a result, create a new imbalance or reinforce one that was already there.
"Even if you go to a yoga class regularly, this doesn't mean you're focusing exactly on the areas that need to be stretched."When you consider that there are over 46 muscles involved in the pedal stroke, it's a lot more complicated than generally stretching the gluteus maximus, quadriceps, hamstrings and calves. A muscle can be tight on the medial or lateral side, deeper or more superficial, and at the origin or the insertion. This sounds complicated, but to Doctors in Physical Therapy, Chiropractors and Doctors of Sports Medicine, this is as much common sense as a red light means stop and a green light means go. Look for trainers or coaches who have a great relationship with these professionals because then you'll be more likely to work with someone who can really help.
"A muscle can be tighter on the medial or lateral side, deep or superficial, and at the origin or the insertion of the muscle."If you'd like to work with me to optimize your crank length, contact me at EatSleepTrainSmart@gmail.com
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