Not all bike fits are created equal.
Many cyclists invest in a professional fit expecting better comfort, improved efficiency, and reduced pain, yet still experience the same issues.
The problem is often not the rider. It’s the process.
Neill Stanbury, RCA’s bike fitting expert, has identified three critical red flags that separate a high-quality fit from a poor one. These aren’t subtle differences, they’re fundamental mistakes that can leave cyclists stuck with discomfort and limitations even after spending hundreds of dollars.
In this article, we break down Neill’s three biggest red flags so you know exactly what to look for before investing in a bike fit.
Why These Bike Fit Mistakes Happen
Most bike fit mistakes come from oversimplifying a complex process.
Neill explains that a high-quality bike fit is not about hitting a specific joint angle, copying a “pro position,” or making quick adjustments to reduce pain.
Instead, it’s about understanding how the rider moves, both on and off the bike.
When fitters skip this deeper assessment, they rely on shortcuts: software-driven adjustments, visual guesswork, and standardized measurements.
That’s where problems begin.
Mistake #1: Relying Purely on Joint Angle Measurements
One of the most common bike fit mistakes Neill sees is fitters relying entirely on joint angle data from motion capture systems.
Many modern bike fit systems use infrared tracking, motion capture markers, and software-generated joint angles. These tools can be useful, but only when used correctly.
Why Joint Angle Measurements Alone Don’t Work
“The issue is not the technology. The issue is how it’s used.”
If a fitter relies purely on numbers like knee extension angle, hip angle, or ankle range, they’re missing the bigger picture.
The same joint angle can be achieved through completely different setups. In many cases, riders focus on adjusting saddle height to match a target angle, but without understanding how their body moves, those adjustments can create more problems than they solve.
For example, you could achieve a 90-degree knee angle by having the saddle slammed all the way forward but really high. Or you could achieve that same 90 degrees by having the seat way back and super low.
Both produce the “correct” number according to the software, but only one will result in efficient, stable, and pain-free movement.
Neill’s Own Experience
Neill himself is a perfect example of why angles alone don’t tell the story.
“My seat looks really low,” he explains. “People look at me riding and go, ‘Gee mate, your seat’s really low. You’re not opening your knee angle right up.’”
But what people don’t see is what Neill looks like under load after two hours of riding, when he drops his heels, his knee extension angle opens up and looks totally normal. Neill’s heel dropping technique is relatively common amongst riders, and creates an unusual problem for the bike fitter.
More importantly, if he raises his seat just five millimeters from that position, he gets knee pain in one knee, as his body attempts to favour his dominant leg due to compensation strategies.
Neill has actually had angle-based fits in the past where his seat was fifty millimeters too high based on software recommendations, completely wrong for his body.
What a High-Quality Bike Fit Should Look For Instead
“You’ve got to be looking at the quality of the movement, not the quantity of the movement. And that’s a much harder thing to see on a screen.”
A skilled fitter prioritizes stability under load, movement symmetry, pedaling efficiency, and pain-free function. Technology should support decisions, not make them.
It’s okay if fitters use tracking software to confirm what they’re seeing, but if they rely solely on that, it’s a red flag.
Mistake #2: Skipping an In-Depth Off-the-Bike Assessment
Another major issue Neill sees is skipping the assessment that happens before the rider even gets on the bike.
What Happens When This Step Is Skipped
Without an off-bike assessment, the fitter lacks context. They don’t know why the rider moves a certain way, where asymmetries originate, or what physical limitations exist.
For example, if a rider is dropping their right hip and their right knee is tracking closer to the top tube, the fitter might adjust the saddle or cleats. But without an off-bike assessment, they have no starting point for understanding what’s causing that movement pattern.
“You need to go into the fit already thinking about what might be causing the movement pattern you’re about to see. Otherwise you’re just blindly reacting to what’s happening in front of you.”
What a Proper Assessment Includes
Neill devotes nearly a quarter of a two-hour session, 20 to 30 minutes at least to looking at riders off the bike.
This includes checking:
- Pelvic alignment and tilts
- Leg length comparison
- Hip mobility and range of motion
- Foot structure and asymmetry
- How they walk and move
- Muscular imbalances between sides
Before the rider starts pedaling, the fitter should already have clear hypotheses, a direction for adjustments, and a plan to test and refine.
“If they just get you down to your knicks, you bend around a bit, then they put the dots on and stick you on the machine be wary.” Neill warns.
Why Neill Doesn’t Do Remote Fittings
This off-bike assessment is one of the main reasons Neill doesn’t do remote bike fittings, even though he gets about five requests per week from international riders.
“There are two problems. One is that we can’t assess you in detail off the bike. And the second one is that there’s too much lost in terms of high-speed motion patterns via video link. I’d rather not do it at all than do it poorly.“
This is also why riders who’ve had multiple bike fits often still struggle with the same issues, because the underlying cause was never properly assessed.
A proper bike fit doesn’t start on the bike. It starts with understanding how your body moves before any adjustments are made.
Mistake #3: Ignoring Structural Leg Length Discrepancies
This is one of the most overlooked yet impactful, bike fit mistakes Neill encounters.
Neill sees many riders come in with one-sided knee pain who’ve had four bike fits before. When he assesses them off the bike, he determines they have something like a four-millimeter shorter right tibia or a six-millimeter shorter left femur.
“Did any of those bike fitters attempt to use a shim?” he asks them. The answer is almost always no.
Why Leg Length Differences Matter in Cycling
“If you’re pedaling, your feet are locked in. The demand for symmetry in our sport is so high that even something like a two- or three-millimeter leg length difference will cause visible motion pattern discrepancies between the two legs.“
Unlike walking or running, cycling locks the feet into a fixed position. Even a 2–3mm difference can lead to uneven force application, knee tracking issues, hip instability, and long-term discomfort.
Why This Mistake Is So Common
Neill thinks this problem came from orthopedics. Textbooks say that any leg length discrepancy of less than about half an inch (12 millimeters) will never cause a problem.
“That’s sort of mostly true,” Neill says, “unless you’re cycling.”
Some fitters dismiss small discrepancies, putting leg length differences in the “too hard basket.” But cycling is repetitive and constrained. Small imbalances, repeated thousands of times per ride, create significant issues, often showing up as persistent discomfort like lower back pain or one-sided fatigue.
The Rare Exception
There are some extremely rare riders whose compensation strategies are so good that you don’t need to address their leg length discrepancy. Neill estimates these riders are ” one or two a year, out of the 500 that I would fit.”
But for 99.9% of people with a leg length discrepancy of two or three millimeters, Neill can spot visible motion pattern issues when watching them pedal.
“If you can’t see them, that means you’re not looking hard enough.“
How a Professional Should Address It
Neill’s approach: assess discrepancies off the bike, observe asymmetry under load, and test adjustments with cleat shims, small increments of 1–3mm placed under the cleat, which ties directly into how to set your cleat position correctly.
Around 75-80% of Neill’s riders leave his clinic with a shim underneath one foot. Often it’s two or three millimeters, sometimes even one millimeter.
Cameron’s Example
Cameron himself had 10 years of right-sided hip pain. Since Neill fitted him with a shim, the hip pain’s gone.
“It’s unbelievably common,” Neill says. “It happens so frequently from expensive bike fitters as well as cheap ones.”
How to Avoid These Bike Fit Mistakes
If you’re investing in a bike fit, look for a process, not just a quick adjustment.
A high-quality fit should include:
- Detailed off-the-bike assessment (20–30 minutes minimum)
- Observation of movement quality under load (not just angles)
- Consideration of asymmetry and structural differences
- Practical testing of changes (like shims)
- Ongoing refinement based on what actually works
Avoid fitters who:
- Rely only on software
- Skip physical assessment
- Ignore asymmetry
- Apply generic positions
If you’re experiencing ongoing discomfort, it’s often linked to deeper fit issues like those seen in cycling knee pain or lower back pain in cyclists.
Frequently Asked Questions About Bike Fit Mistakes
What are the most common bike fit mistakes?
The most common bike fit mistakes include relying only on joint angle measurements from motion capture software, skipping detailed off-the-bike physical assessment, and ignoring structural asymmetries like leg length discrepancies. These mistakes lead to positions that look correct numerically but don’t work for the individual rider.
What are signs of a bad bike fit?
Common signs include persistent discomfort that doesn’t improve, asymmetrical pedaling patterns, recurring pain in knees or hips, and lack of improvement despite multiple adjustments. If issues remain after a fit, the fitter likely missed structural causes or relied too heavily on software.
Is a professional bike fit worth it?
Yes, when done correctly. A proper fit improves comfort, efficiency, and long-term performance by addressing how your specific body interacts with the bike. The key is choosing a fitter who conducts thorough off-bike assessment and looks at movement quality, not just angles.
Can a bike fit fix knee or hip pain?
In many cases, yes, but only when the root cause is properly identified. For example, Cameron had 10 years of right-sided hip pain that disappeared after Neill identified a leg length discrepancy and added a small shim.
How long should a proper bike fit take?
A high-quality professional bike fit should take 2–3 hours, with 20–30 minutes dedicated to off-bike physical assessment. If a fitter rushes through in under an hour or skips the off-bike evaluation, that’s a red flag.
What is a cleat shim and when is it needed?
A cleat shim is a thin spacer (typically 1–3mm) placed under the cleat to address leg length discrepancies. Even small differences of 2–3mm matter in cycling because your feet are locked into the pedals. Around 75–80% of Neill’s riders leave with a shim after proper assessment.
Conclusion: The Standard You Should Expect From a Bike Fit
A bike fit is not just a service, it’s a process. And the quality of that process determines the outcome.
As Neill makes clear through his three red flags, the difference between a good fit and a poor one comes down to whether the fitter looks beyond numbers to focus on movement quality, individual structure, and proper assessment.
When those elements are in place, the result is not just a better position, but a stronger, more efficient, and pain-free rider.
If you’ve had a bike fit before and something still doesn’t feel right, or you’re considering one for the first time the difference usually comes down to the process behind it.
At Road Cycling Academy, Neill’s approach is built around detailed off-the-bike assessment and real-time movement analysis, so your position reflects how your body actually functions, not just what the numbers say.
If you want to understand what’s really limiting your position, this is where that process starts.