CogPair is an independent site that works out bicycle tire pressure, gearing and chain length.
It exists because drivetrain questions are answered in forum threads and gear ratios in spreadsheets, and neither is any use with the bike in a workstand and a chain in your hand.
Where the numbers come from
- the 15% tire drop curve from Frank Berto's testing, via Jan Heine in Bicycle Quarterly
- Sheldon Brown's gain ratio, which is the only common gearing measure that accounts for crank length
- the Park Tool and Shimano chain length formula
Every page states the source and the assumptions behind its figures, because a number without its assumptions is not much use. Where a figure is a fitting convention rather than a measured value, the page says which it is.
Harder is not faster
Higher tire pressure is not faster. Above a certain point rolling resistance goes back up on real road surfaces, because the tire stops absorbing small irregularities and starts lifting the whole bike over them.
What this site does not do
We do not give frame sizing or fit advice. That is a fitting done in person, and a number from a web page is a poor substitute for it.
Who runs it
One person who rides more than is sensible and maintains this in the off-season. There is no editorial team. Instead every number names the standard, the manufacturer chart or the formula it came from.
The gearing maths runs as code across every chainring, sprocket and crank combination on the site, so an error in a constant shows up across the whole set. Errors get corrected, with a note recording what changed.
How it is paid for
CogPair is free to read and funded by display advertising. Nothing here is sponsored and there are no affiliate links. No component brand has any say in these numbers.
Getting in touch
Corrections and questions go to [email protected]. A correction is the most useful thing you can send — the editorial policy covers what happens to one.