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Bike Fit Calculators

Frame sizing, saddle height, reach, stack and positioning calculators.

10 free calculators in Bike Fit

Understanding Bike Fit for UK Cyclists

A proper bike fit is one of the most important investments any cyclist can make, whether you are commuting through central London, tackling sportives in the Yorkshire Dales, or training for British Cycling time trials. Poor positioning is a leading cause of knee pain, lower back discomfort, and numbness on long rides — issues that become particularly noticeable on the UK's often rough and poorly surfaced roads. Our frame size calculator and saddle height calculator use your body measurements in centimetres to recommend starting positions based on widely accepted fitting methodologies.

Getting your reach and stack dialled in is essential for both comfort and aerodynamic efficiency. The stack and reach calculator lets you compare geometry across different bike sizes, while the stem length calculator helps fine-tune your cockpit without needing a full professional refit. For riders using clipless pedals, the cleat position calculator provides a starting point that can prevent hotfoot and knee tracking issues over longer distances.

While these calculators give you an excellent foundation, many UK bike shops and organisations like Cycling UK recommend a professional bike fit for serious riders — especially those covering high weekly mileage or recovering from injury. Use our tools to understand your measurements before a fitting session, or to make informed adjustments between visits to your local fitter.