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The Importance of Femur Length, Not Just Height, in Saddle Fit and Rider Biomechanics.
One of the most overlooked factors in saddle fit is femur length. While most people focus on rider height and weight when matching a rider to a horse saddle, leg proportions—particularly the length of the femur (thigh bone)—can significantly impact riding position, balance, comfort, and biomechanics.
A regular rider physio client messaged me recently, feeling frustrated and confused after what had otherwise been a great period of progress. As a novice rider, she had been seeing big improvements in her riding position and stability since starting rider physio sessions. She was feeling more secure in the saddle, more in control, and finally understanding how to move with the horse.
Then, this week, everything changed. A new riding instructor, a new horse, and suddenly she was receiving advice that contradicted everything she had been working on! She felt lost, unsure what to believe, and questioning everything.
Luckily, as a rider physio subscription client, she was able to send in videos of her riding for analysis. Straight away, the issue became clear: the saddle was too small for her femur length.
At 5ft 2 and light, she was considered the right size for a 13.2 pony—but what hadn’t been taken into account was her femur length and how it affected her seat position.
Why Femur Length Affects Saddle Fit More Than Rider Height
The femur (thigh bone) is one of the last bones in the body to finish growing. In children and adolescent riders, the legs may appear long in proportion to their torso, but that’s because they are still growing into their adult proportions.
An adult rider of the same height as a child will typically have a longer femur, which can completely change how they sit in the saddle.
In this case, her femur was too long for the saddle. This meant that every time she rode:
Her knee was being pushed too far forward, disrupting her leg position and balance.
Her pelvis was hitting the back of the saddle, causing likely discomfort of the horse.
The instructor told her to tilt her pelvis forward to compensate, which was the exact opposite of what she had been working on in rider physio sessions.
She struggled to keep hip-heel alignment because her legs were being pushed too far forward.
Lengthening the stirrups didn’t help, because the problem wasn’t stirrup length—it was the saddle size.
A Common (and Difficult) Conversation with Clients
This isn’t an isolated case—I have this conversation with clients all the time as an equine physio, especially when teenage riders go through a growth spurt.
One of the most misunderstood aspects of saddle fit is that it’s not just about weight.
Many parents worry that their child has outgrown their pony because of weight, but in reality, the issue is often femur length pushing the rider’s weight too far back in the saddle.
It’s not that they’re too heavy for the pony.
It’s that their long legs mean their weight is positioned at the back of the saddle, creating pressure points.
This often causes discomfort for the pony, which is why they’ve called out the equine physio in the first place!
When a rider’s femur length no longer fits the saddle, it changes their balance and shifts their weight further back, creating the very problems they are trying to fix.
What the Video Analysis Showed
I showed this client the difference in her thigh angle between her recent simulator sessions and her last riding lesson.
In the simulator saddle, her knee was in the correct place, and she could find a neutral pelvis and spine position.
In the real horse saddle, her knee was too far forward, and the angle of her thigh was much smaller because she was crammed into a saddle that didn’t accommodate her leg length.
Why This Matters for Saddle Fit and Rider Biomechanics
When a saddle doesn’t fit a rider’s femur length, it forces them into poor riding posture, affecting:
✔ Rider balance and stability
✔ Leg position and hip-heel alignment
✔ Pelvic alignment and spinal posture
✔ The horse’s comfort and movement
In this case, the rider’s femur length required a slightly larger saddle—one that could accommodate her thigh length without pushing her out of alignment.
This situation is a perfect example of why height alone does not determine the correct saddle size. Every rider’s body is different, and we must consider proportions, especially femur length, to ensure a proper saddle fit.
Key Takeaways for Saddle Fit:
✅ Femur length, not just height, plays a critical role in saddle fit.
✅ An adult rider will usually have a longer femur than a child of the same height.
✅ A saddle that is too small can force the rider into poor posture, affecting balance and leg position.
✅ If a teenage rider is growing, their femur length may be shifting their weight further back—causing the very problems the equine physio is called out to assess!
✅ Proper saddle fit is essential for both rider biomechanics and horse comfort.
✅ Video analysis and rider physio sessions can help identify saddle fit issues before they cause bigger problems.
This is exactly why working with professionals who understand rider biomechanics, equestrian saddle fitting, and horse movement can make such a big difference in riding performance, rider comfort, and horse welfare.
Saddle Fit vs. Simulator Work
While the saddles I use on the simulator don’t always fit every rider perfectly, we don’t have to worry about pressure on the back of the saddle—because a mechanical horse doesn’t feel discomfort!
This means that in a GP or dressage saddle without knee blocks, we can nearly always find neutral spine and pelvis alignment for the rider.
Explaining this to riders in their rider physio sessions helps them understand:
How saddle fit affects their riding position
How to improve flexibility, strength, and control to adapt to different saddles
Why biomechanics and balance matter more than just saddle size
Final Thoughts
This was a great learning moment for this client, and hopefully, it helps other riders think beyond height when choosing the right saddle.
If you’re struggling with riding position, saddle discomfort, or sudden changes in performance, consider:
🔹 Assessing your femur length in relation to your saddle fit
🔹 Using video feedback to analyze your position
🔹 Working on biomechanics and balance through rider physio
📹 Confused about your riding position? Get video feedback and biomechanics coaching inside the Rider Physio Subscription or book in for a session on the mechanical horse.
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