Know which bike fits before you buy it.
Forty-five minutes with a professional fitter, by video. We measure you, work out the exact position you need, and tell you which bikes and which sizes reach it.
A size chart is a guess about someone who isn't you.
Manufacturer size charts take one number off you, your height, and hand back a frame size. But height isn't what sets how far you can comfortably reach. Your inseam does, and your torso, and your arms, and how far your hips will rotate before your back has to round.
A frame has proportions of its own. Stack is how high the handlebars sit above the bottom bracket, reach is how far in front. Long legs and a short torso ask for a tall stack and a short reach. Short legs and a long torso ask for the opposite. Going up a size buys you around 20mm of stack but only 8mm of reach, so size on its own can't put you where you need to be.
Two riders at 178 cm can need frames a full size apart. Two others can need the same size in different shapes. A size chart sees none of it, and nor does ten minutes in a shop that stocks four bikes in three sizes, none of them the one you came in for.
The category names don't rescue it. Endurance and race describe what the designer had in mind, not what your body can do. Riders reach racing positions on endurance frames all the time, and a rare few find an endurance position on a race frame. What settles it is not the label but whether the frame's proportions and yours line up.
So most people buy on height. They ride for six months in a position that's slightly wrong in a way they can't name, and then pay for a bike fit to make the wrong frame less wrong.
A bike fit optimises the bike you own. Sizing decides which one to own.
By the time you're on a fitting jig, the money is spent. A fitter can move your saddle 20mm and change your stem by 20mm. They can't touch your frame's stack and reach, and between sizes those step by roughly 20mm of stack and only 8 of reach. You fix them the day you pay.
Think of it as a box. Every frame can be set up to put your handlebars anywhere within a certain range, using whatever stem and spacer stack you like. The frame decides where that box sits. The fitter works inside it.
So two frames can both reach your position and still be a different decision. One puts you in the middle of its box, with room to move as you age or your flexibility changes. The other reaches you at full stretch and has nothing left to give.
Sizing happens before that, while every brand, model and size is still open to you. It's also the stage almost nobody does properly.
Four steps, one session
Book and prepare
Pick a time and pay. You'll get a confirmation, a video call link and a short intake form. Before the call, set your current bike up on a turbo trainer.
Measure where you are now
On the call we take your body measurements, then film you riding side-on. The video shows the position you're in today, and lets us measure your torso and arm length directly instead of estimating them from your height.
Build the position you need
Your fitter compares what your anatomy calls for against what your body actually does, then builds one target: an exact handlebar coordinate, saddle height and setback, and crank length.
Match it to real bikes
That target goes into the geometry database and we run it against real frames. You get a ranked list of bikes and sizes that reach it, and the ones that never will.
What your report contains
- Your target hood position: the X and Y of your handlebars from the bottom bracket. This is the number every size chart in the industry is approximating.
- Saddle height, setback and crank length, with the crank based on your leg length rather than whatever the manufacturer fitted.
- A ranked shortlist of bikes and sizes that reach the target.
- The setup each one needs: stem length and angle, spacer stack, handlebar reach, seatpost.
- How much adjustment each one leaves you afterwards. A bike that reaches you only at maximum spacers with a 130mm stem has nowhere left to go.
- The bikes to avoid, and why.
- A confidence range around your position, so you can see how much of the answer is solid and how much is inference.
- A written report you keep and can take to any shop.
Before you book — what you'll need
Read this bit properly. Half the value of the session comes from watching you ride, and we can't do that if you're not set up.
You'll need:
- Your current bike, on a turbo trainer or stationary trainer. Not rollers, and not leaning against a wall.
- A phone to film with and someone to hold it, or a tripod. Side-on to you, roughly hip height, held still.
- A tape measure and a hardback book. We'll walk you through the inseam measurement on the call.
- A laptop or tablet for the call. Your phone will be busy filming, and you need to see the screen while we work.
- Forty-five uninterrupted minutes, and room to move around the bike.
Buying your first bike, or sold the old one?
Say so when you book. We'll run an anthropometry-only session: body measurements, target position, ranked shortlist, same written report. What's missing is the comparison against how you currently ride, because there's nothing to film.
The answer is still useful. It just rests on less, and we'd rather say so now than after you've paid.
What we don't do
We don't do bike fits.
No treating pain, diagnosing injuries, adjusting the bike you already own or working on your pedal stroke. If you need any of that, book an in-person fit.
We don't give medical advice.
If something hurts, see a physiotherapist or a doctor first.
We don't guarantee a position to the millimetre.
Your target is a modelled centre point with real uncertainty around it, and the report shows you that uncertainty. Anyone promising you a bike size to the millimetre off a video call is selling certainty they don't have.
We don't take money from manufacturers.
We don't sell bikes and nobody pays for placement in your report. If the bike you want is wrong for you, the report says so.
That's the whole thing.
No membership, and nothing we try to sell you at the end.
The numbers it sits against:
- A professional bike fit — and it happens after you've bought the frame.$200–400
- Depreciation on a bike you sell inside a year, on a £4,000 bike.£1,000–1,500
- A bike you keep and never quite enjoy.Harder to price
Questions people ask before booking
Do I really need a turbo trainer?
For the full session, yes. Filming you ride is how we measure your torso and arm length instead of estimating them from your height, and that measurement is what makes the answer yours rather than average. Without it we can run an anthropometry-only session and tell you plainly what we couldn't check.
Is this a bike fit?
No. A fit adjusts the bike you own; this decides which bike to own. Read the full comparison →
What if I don't like the answer?
Then it did its job. We'd rather tell you the bike you want is wrong for you before you spend the money than agree with you afterwards.
Can you size me for a bike that isn't in your database?
Usually. Send the geometry chart when you book and we'll add it. If it isn't published anywhere we'll tell you before the session rather than waste your time.