Your bike fitter · Topsham, Exeter

Meet Jon Underhill

Founder of CORE Bike Fit. IBFI Level 2 bike fitter. A cyclist who wants to help you enjoy your riding.

CORE means Creating the Optimal Rider Experience. For me, that starts with understanding the person on the bike.

Why I started CORE Bike Fit

Hi, I’m Jon. Cycling has been part of my life since I was young. I’ve always enjoyed understanding how things work and helping people get more from themselves. In 2022, I brought those interests together and founded CORE Bike Fit in Topsham, near Exeter.

My aim is simple: to help you find a position that works for your body, your riding and your ambitions. You might be new to cycling, planning longer rides, returning to the bike or looking to refine your performance. You don’t need to be a racer to benefit from a thoughtful fit.

Underhills · Our Topsham roots

A family connection, generations in the making

My family’s connection to Topsham goes back generations through Underhills shoe shop. Had I carried on the family trade, I would have been the fifth generation of shoe repairers.

Growing up, I learnt to repair shoes alongside my dad, who was also a keen local cyclist. Feet, footwear, bicycles and practical craftsmanship were part of my life long before CORE Bike Fit.

The same place, a different craft

Today, CORE Bike Fit is based in the building behind the old Underhills shoe shop. My workshop is where my dad’s workshop was, and the original Underhills sign has a home here too.

I took a different path, but that connection remains: working with my hands, paying attention to the details and helping people feel more comfortable—now on their bicycles. That family background also helps explain my particular interest in the foot, shoe and pedal connection.

Video stills: Topsham TV. Watch the film of Underhills’ closing-down sale →

A fitting approach built around you

I start by listening. Your experience on the bike, what you want to change and how you want to ride all matter. Measurements and technology help inform the decisions, but your feedback remains central throughout the session.

I work through the connections between you and the bike: your feet, shoes and cleats, saddle position and cockpit. My family background in shoes and feet has shaped a particular interest in the foot–shoe–pedal connection.

From an adjustment to your existing bicycle to exploring the geometry of a new one, the goal is a position you can use and understand, with clear recommendations to take away.

Qualifications and continued learning

• IBFI Level 2 bike fitter — International Bike Fitting Institute.
• Applied Movement Neurology, Level 1 training.

I combine that training with practical fitting experience, careful observation and your feedback. Where appropriate to your chosen fit, I use the Purely Custom fit jig and Velometrik saddle pressure mapping to explore and assess changes.

See how a bike fit works →

More than an appointment

I’ve worked with riders ranging from professional athletes to people who cycle simply for enjoyment. Every rider brings a different story, and every session should reflect that.

I also created CORE Bike Club as a welcoming place to ride, learn and share a love of cycling. Helping people feel more confident on their bikes is part of what makes this work rewarding.

CORE Bike Fit · 16A Fore Street, Topsham, Exeter, Devon, EX3 0HF