The Advantages of Long Femurs In Cycling Are
- Longer Cranks
Longer femurs position the knees further away from the bottom bracket than shorter cranks.
Consequently, the rider can pedal with longer cranks without experiencing extra knee stress.
The longer cranks act as a long lever and offer a greater mechanical advantage.
If someone with much shorter femurs uses maximally long cranks, knee discomfort might appear.
- More “Useful Mass”
Upper body mass is irrelevant in the world of cycling. The sport is entirely lower-body dominant.
People with long femurs have short torsos. Thus, those cyclists have more “useful mass” by default as their legs form a greater percentage of their bodies.
- Less Drag
Most of the body drag comes from the torso. People with long femurs have short torsos making it easier to assume a more aerodynamic position without feeling uncomfortably stretched.
- Long Femur = Larger Frame
The size of the frame that a cyclist needs is greatly influenced by the so-called inseam or the distance between the rider’s crotch and the floor. Long femurs result in a longer inseam which demands a larger frame.
A larger frame comes with both pros and cons. The cons are that the frame is more difficult to maneuver and weighs more.
However, a larger frame also has a long wheelbase (distance between the axles) resulting in greater stability and speed during descents.
What does science say about the subject?
A study entitled “Anthropometric Comparison of Cyclists from Different Events”, and conducted by J.P. Foley, S.R. Bird, and J.A. White compared the difference in limb length among 4 groups of cyclists – sprint, pursuit, road, and time trial.
The conclusions of the study were:
- Sprinters had the shortest femurs and were the most muscular overall.
- Time trialists were the skinniest and had the longest femurs of all groups.
- Pursuit and road cyclists had no significant anthropometric differences and fell somewhere in between the other two groups.
You can find the full study here.
FAQ: How do I know if I have long femurs or not
If your legs make up more than 50% of your height, then you have long legs.
And if your legs are longer than your tibia (lower leg), which is usually the case for people with long legs, you have long femurs.
It’s important to note that it’s about proportions rather than height even though many people with long femurs are on the taller side.
Another indication of long femurs is found in the gym during squats. People with long femurs and short torsos have to bend over more during weighted squats to remain balanced. As a result, the squat becomes hip rather than leg-dominant and hits the glutes harder.
For that reason, people with long femurs do not always consider the squat a good leg (quadriceps) builder and experiment with other movements (e.g., hack squats.)
FAQ: What are the downsides of having long femurs?
The main issue with long femurs is finding a frame that is large enough for your legs, but not too big for the rest of your body. The shorter your arms are, the more likely you are to experience issues with your fit.
That said, most people with long femurs tend to have long arms too. The longer arms make the bike fit less “pretentious” because they compensate for the lack of torso length when using a large frame dictated by a long inseam.
In some cases, however, it may be necessary to get a shorter stem to bring the handlebars closer to your body. In extreme situations, when the rider has very short arms in comparison to their legs, a custom frame could be needed for optimal pedaling and comfort.
Ultimately, however, long femurs do not have major disadvantages that would stop one from achieving success if the rest of the “equation” is correct.
Factors That Outweigh The Importance of Femur Length
Long femurs have advantages, but there are other significantly more important factors that contribute to cycling success. Those would be:
- Training & Discipline (even if you have the perfect body for cycling, it doesn’t mean much when you aren’t training sufficiently.)
- Lung capacity
- Fiber type distribution
There are fast and slow twitch muscle fibers. Fast-twitch dominant people excel at sprinting while slow-twitch athletes do better in endurance events. The average person has somewhat of an equal (50/50) fiber type distribution.
Even if a person has the perfect body structure and fiber distribution for success, those can’t compensate for the lack of desire to reach a higher level.
- Bike Fit + Equipment
If your bike fit is poor and you’re riding a subpar bicycle, you won’t be able to reach and show your full potential. Of course, no one needs a 20k bike to be a decent cyclist, but riding an uncomfortable machine with outdated tech (e.g., downtube shifters) comes with a massive disadvantage.
- Encouraging and Competitive Environment
Another important factor for success is the environment. For example, if you are born with less-than-ideal femur length, but your entire family is made of cyclists who know what it takes to succeed, you have a much higher chance of succeeding in this sport thanks to the support and wisdom coming from the people around you.
An Important Note – Do Not Overthink
Overthink represents the act of obsessing over details that are either unimportant or not in your control. In both cases, you’re spending energy that doesn’t contribute to forward motion.
I’d say that obsession over femur length falls into this category too. It’s much more important to have the aforementioned factors in good order than an “optimal” femur length.