Tommy Canuck

I did the on line sizing test just to have some idea of what size bike I should be looking for. Now I am totally confused. I was looking at 53 CM bikes and I thought that most bikes had very similar top tube and seat tube lengths. I thought a 53 cm bike meant that the seat tube measurement was roughly 53 as well as the top tube roughly 53. Anyway, below are my results of the sizing test. I have no clue where this points me as far as what size I need. I checked and double checked my measurements so they are bang on. Would I fit better into a 51 or 53 cm bike? Here are the results:

Comp fit Eddy fit French fit

Seat tube range c-c 50.2 -50.7 51.4 - 51.9 53.1 - 53.6
Seat tube range c-t 51.7 -52.2 52.9 - 53.4 54.6 - 55.1
Top tube length 56.3 - 56.7 56.3 - 56.7 57.5 - 57.9
Stem Length 11.2 - 11.8 10.1 - 10.7 10.3 - 10.9
BB-Saddle Position 69.8 - 71.8 69.0 - 71.0 67.3 - 69.3
Saddle-Handlebar 54.0 - 54.6 54.8 - 55.4 56.5 - 57.1
Saddle Setback 2.9 - 3.3 4.1 - 4.5 3.6 - 4.0
Seatpost Type NON-SETBACK NON-SETBACK SETBACK

CycleFreakLS

You do realize that not all manufacturers measure seat tube height the same. Some measure center to center, others center to top. A Trek 54 is like somebody else's 52. The only way you'll know is to go down to your LBS-s and try 'em all.

First I think you should decide what type of riding you want to do. Racing, scaling cliffs like a goat, (shudder) a TT, or just a your everyday roadie (maybe less aggressive than racing). Second, decide how much $$$ you're willing to part with. Third, visit a whole bunch of web sites and start making an Excel sheet of frames, materials, and estimated sizes. Then, go find an LBS and start trying 'em on.

Best.

Dave Moulton

I don’t know if you would find a frame with that seat and top tube combination. Also I don’t know what your measurements are, but this seems like a very long reach and I’m not sure this is what you need.

Go to my website; the link is below then Bicycles > Page 6 Bike Tech. There is a very simple to read chart. You may not find a frame with the exact same top tube length, so adjust the stem length accordingly. Also the chart is for a racing position so again chose a frame a centimeter bigger and the reach a centimeter shorter if you are looking for a more relaxed position.

sydney

And some measure to the top of an extended seattube. Assuming adequate standover,worry more about TT length and the ability to have the bars at the proper position.

sydney

You aren't going to find traditional frames with that kind of seattube/toptube ratio.Standard geomety just does't come with toptubes that long for the given nominal sizes. Assuming your measurements and calculations are even correct, you need to be thinking custom.

MichaelW

There are some brands which are longer than other for any given size. You will have to check out the geometry charts, but take a look at Lemond for long frames.
These days, ST is less than critical; the fashion is for plenty of standover clearance. Size your frame by TT. You can get the same reach with differnt combos of TT and stem. There is no formula for picking the right one, but a medium stem 10-12cm will work for medium bikes.
Your riding style affects the reach you need. Most fit guides assume that you need a long, low aerodynamic position, but you may be happier with a more relaxed touring style. It is up to you.