By looking at the specs on Redline's website it seems that the only difference between the 48cm and 50cm bike is the seat tube length. Am I currect in assuming this? It's wierd how they measure their bikes, I have a 50cm Redline right now that has a 50cm seat tube of 50cm c-c and about 55cm c-t but a top tube of only 52.2 and I have a slightly longer stem on there, a 110 because I ride a road bike with a 54cm top tube and 100m stem. Now, I know that people say that when you're sizing a bike it doesn't really matter what the seat tube is as long as the top tube is your size but the whole reason why I got the 50cm is because the 52cm which had a top tube of 53.5cm had a seat tube c-t of like 57cm so I actually couldn't get my seat down low enough. If everything but the seat tube is the same on the 48cm and 50cm I'm actually thinking bout going for a 48cm but the bike shop said it would be too small for me? But how would it be too small with the same size top tube and a c-t seattube of like 53cm? My current road bike has a seat tube length c-t of 50cm but TT of 54cm. Anyone have any comments about this?