Phil Bert, a former Team Sky and GB bike fitter who's worked with Olympic champions and Tour de France winners, breaks down the five most common bike fit mistakes cyclists make — and crucially, how to fix them. We dig into crank length, saddle comfort, back pain, knee health, and why your position matters far more than you probably think.
Key Takeaways
- Crank length is the foundation of everything: most riders are on cranks that are too long, which closes your hips and forces compensations throughout your position. Dropping 5mm can meaningfully improve comfort, reduce asymmetry, and unlock power by letting you sit higher and further forward.
- Saddle pain isn't usually about the saddle: get your position right first (especially crank length and saddle height), then find the right saddle for the job. Pressure mapping technology can reveal exactly where you need support and forgiveness.
- Back pain almost always comes from cranks that are too long: tight hip flexors from a closed hip position force your pelvis back and load your lower spine. Shorter cranks let your pelvis move forward and remove strain before you ever consider stretching routines.
- Knee pain responds best to cleat position and pedal choice: move your cleats further back (under your arch rather than your toe), and consider pedals with float if you have asymmetries. The knee is locked in place, so small positioning changes have big effects.
- Adjust the bike to the person, not the person to the bike: most cyclists are remarkably adaptable. Rather than expecting someone to spend hours stretching tight hip flexors, move saddle, crank length, and cleats to work with their body as it is.
- Marginal gains philosophy applies differently to amateurs: while pros chase 1–2% improvements, most recreational riders have 20–25% headroom. Spend time and money on the things that shift the dial: crank length, saddle fit, and cleat position matter far more than an aero bike or expensive upgrades.
Expert Quotes
"If you're riding the wrong crank it's like driving around with a handbrake on. It's literally limited. — Phil Bert"
"The limiting factor in getting power is crank length. Saddle height and forward is where power is. — Phil Bert"
"We won't know if it works in hour four, five, six until you ride it, but the durability of fit comes down to three pillars: aero, power, and comfort sustainability. Those pillars change depending on what you're trying to do. — Phil Bert"