Depends on how you use the bike too. I mentioned a long ride as I find my reach only settles in after a few km, as my aging back needs time to stretch. Also as mentioned by Chris667, bar height is important.
I have a track frame with a short top tube, and a large drop to the bars;
a cyclocross frame with a medium top tube, and a small drop to the bars;
and a 29er with a long top tube, and zero drop to the bars.
Its all a bit trial-and-error for me. But I'd be careful not to be fooled by a short test ride on someone elses bike. A short reach set-up can feel great at first but become cramped as the body warms up.
Anyway back too the original question about searching EBay. The only tip I can offer is to get used to the look of a 52cm frame and browse the pics. Its often easier to look at the head tubes, to judge size. I've become quite good at spotting 53's myself ;)
Depends on how you use the bike too. I mentioned a long ride as I find my reach only settles in after a few km, as my aging back needs time to stretch. Also as mentioned by Chris667, bar height is important.
I have a track frame with a short top tube, and a large drop to the bars;
a cyclocross frame with a medium top tube, and a small drop to the bars;
and a 29er with a long top tube, and zero drop to the bars.
Its all a bit trial-and-error for me. But I'd be careful not to be fooled by a short test ride on someone elses bike. A short reach set-up can feel great at first but become cramped as the body warms up.
Anyway back too the original question about searching EBay. The only tip I can offer is to get used to the look of a 52cm frame and browse the pics. Its often easier to look at the head tubes, to judge size. I've become quite good at spotting 53's myself ;)