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BikeTwins
How it works
behind forward up up BB 0 / 0 behind forward up up A B BB 0 / 0
Your saddle rail centre
Your bar clamp
clamp to the hoods; blank means a typical 75 mm bar

I have my numbers

Give me the four numbers and I go straight to the sizes. Nothing is named, nothing is owned, nothing saved.
The band
Nothing assumed, so the band starts at ±3 mm at the bar and ±3 mm at the saddle.
Where do I find these?
The two points
Everything on this site is these two points and the bottom bracket. Both measured from the bottom bracket, the middle of where the cranks turn. If your report gives them as coordinates, this is them.
Saddle, behind the BB
the middle of the saddle rails, behind the cranks
Saddle, up from the BB
the middle of the rails, above the cranks
Bar, forward of the BB
how far in front of the cranks the middle of your bar clamp sits
Bar, up from the BB
how far above the cranks it sits
Your bar reach
The bar's reach is the one box you can leave empty without being asked again: I stand in a typical 75 mm bar, say so on every answer, and the bar band opens from ±3 mm to ±8 mm to cover it. Your own two points do not move; what moves is where the hoods land on a bike wearing a different bar.
The two bands
The two points are the tightest of the two: nothing is assumed, so the band starts at ±3 mm at the bar and ±3 mm at the saddle. The figures on a fit report are what most reports actually print: I convert them, and the saddle band opens to ±10 mm because the conversion assumes things.
Off a fit report
If you have had a fit, every report I have seen prints the four figures on the second tab. Type them in as they are written.
Off the bike you ride
About two minutes: pick it from the list by make, model and size, and I work the position out from the frame and the parts. Start from a bike
With a tape
About twenty minutes with a tape, a plumb line and a level, and afterwards nothing about your own bike is assumed. The guide has the pictures; you come back and type the two points in. How to measure your bike
Nothing saved
I will not invent a stem you never told me about. The numbers travel in the address bar, so you can come back to them or send them to somebody. The offer to keep the numbers comes after the answer, if you want it.