How an unsuitable saddle contributed to an imbalanced riding position—and a noticeable difference between his legs
Robbie is an experienced road cyclist who has been riding recreationally and consistently since the mid-1990s. His garage is full of older favourites, collector’s bikes and machines accumulated over decades of riding.
By any measure, he is a cycling veteran and a genuine enthusiast. But even experienced riders can have a wake-up call when it comes to their position on the bike. A few months ago, Robbie had exactly that.
“I just always rode that way.”
Photo from left - Gabe (author), Robbie, Adrian - and then Robbie's Pre-Fit assessment. That's not an optical illusion, his left leg is considerably larger to his right leg.
The first clue: an uneven pedal stroke
During one of our Saturday Urban Pedaler Shop Rides, I found myself riding behind Robbie. While keeping an eye on the group, our speed and potential obstacles, I noticed that his pedal stroke looked unusually choppy.
Rather than producing a smooth, continuous circle, there appeared to be a noticeable interruption in both legs as the downward push from the quadriceps transitioned into the involvement of the hamstrings and glutes through the back of the stroke. The different muscle groups seemed to be working against each other rather than contributing to one fluid movement.
I watched him for a while, trying to understand what might be causing it.
After the ride, over coffee, I mentioned what I had noticed and invited Robbie into the store for a bike fit—or at least an initial assessment to establish whether a bike fit might benefit him.
The saddle told a story
I had never examined Robbie’s bike or equipment closely before. Once we did, however, the saddle immediately stood out.
As shown in the photograph, a significant area of the saddle’s surface had worn away on the right side. The corresponding area on the left was relatively untouched, although there was a separate rub mark closer to the nose.
These were unusual and clearly asymmetrical wear patterns. They suggested that Robbie had not been sitting squarely or distributing his weight evenly across the saddle.
Using a model pelvis, I showed Robbie how the sit bones should ideally be supported by a correctly sized and positioned saddle.
When a saddle is too narrow—or when a rider sits too far forward, sometimes because the reach to the handlebars is excessive—the pelvis may rotate or shift as the body searches for a stable support point. Twisting the pelvis can effectively narrow the distance between the sit bones and allow one side to find more purchase on the saddle.
We had seen similar patterns before (see case study link at bottom), and it did not take long for Robbie to decide that a complete bike fit was worthwhile.
Assessing the rider—not just the bike
A professional bike fit involves much more than adjusting saddle height and moving the handlebars.
We assess factors including:
- Flexibility through the major muscle groups
- Core strength and stability
- Differences between the left and right sides
- Functional leg-length discrepancies
- Joint movement and range of motion
- The rider’s posture and movement on the bike
One of the most obvious findings during Robbie’s physical assessment was the visible difference in circumference between his left and right legs. The difference could be seen through both the thigh and calf.
We document observations like these before putting the rider on the GURU bike-fitting machine. Understanding the rider’s body helps us interpret what we see in their posture and pedal stroke—and guides the changes we test during the fitting process.
Connecting the saddle, pelvis and pedal stroke
Robbie’s sit bones measured considerably wider than the saddle he had been riding.
On the bike, his pelvis appeared to have adapted by rotating towards the right as his body searched for a stable position. This allowed his right sit bone to plant more firmly on the saddle and gave that side a more secure platform from which to produce power (hence the wear marks).
His left sit bone, however, appeared to receive substantially less support.
Without a stable contact point beneath that side of the pelvis, the muscles in Robbie’s left leg may have been working harder to stabilise his body throughout the pedal stroke. Over time, this pattern was likely one factor contributing to the noticeable difference in muscle development between his legs.
Robbie took the assessment photograph home and showed his wife. They were both astonished. Neither had previously noticed the difference, yet once it had been identified, it was clearly visible to the naked eye.
It was obvious that we needed to make some changes.
Selecting a more suitable saddle
During the bike fit, Robbie tried several different saddles. We ultimately selected a 155 mm Prologo Dimension Space.
The wider platform provided substantially better support beneath both sit bones, while the central relief channel helped reduce pressure through the middle of the saddle. We then positioned the saddle to support Robbie properly without encouraging him to slide forward or rotate his pelvis in search of stability.
The goal was not simply to install a wider saddle. It was to create a position in which Robbie’s pelvis could remain more stable and his legs could contribute more evenly to the pedal stroke.
The result
Robbie is now adapting to his revised bike-fit dimensions and relearning a movement pattern that had developed over many years (on a new Cannondale Supersix, I might add).
His pedal stroke has already become noticeably smoother, and he has experienced a significant improvement in his position and stability on the bike. The difference in muscle mass between his legs will naturally take time to change, but the underlying riding position is now far better balanced.
Robbie’s experience demonstrates an important point: time on the bike does not automatically guarantee a well-matched position.
Even highly experienced riders who believe their equipment is completely dialled may still have opportunities—sometimes small and sometimes substantial—to improve their comfort, power, stability and endurance.
Sometimes the rider adapts to the bike so gradually that the compensation simply feels normal.
As Robbie put it:
“I just always rode that way.”
Bike Fitting performed by Paul Davis, fitter extraordinaire, blog post written by Gabe Sullens
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More on the subject
Here is a similar case study we had in 2010 while we were developing a global bike fitting program at Specialized and had the opportunity to work with some exceptional athletes:
