Originally Posted by
corrado33
Interesting. We were thinking of giving this bike to a person in need who was 6"9'. It's the biggest bike we've ever had in the shop, so we had no other choice. It's also pretty beat up, hence us giving it away. (After we fix it up.)
With traditional steel bikes with a horizontal top tube and just a fistful of seatpost showing, the rule of thumb in my day was that the frame size should be 10 inches - 25 cm - less than the inseam measurement. In my case the latter is 88cm, so the theoretical frame size is 63cm. And it turns out that works in practice, though obviously top tube length is also highly material.