Okay, knowing that most will say you've got to sit on it, for now let's assume this isn't possible.
I'm 6' tall with a 32" inside leg and usually ride a bike with a 23-23.5" top tube.
Am I going to be looking toward a 56cm or 58cm frame assuming the tt lengths are 56 and 57cm respectively?
Help appreciated please.
Cheers,
M
If your new to road biking then I would only ever buy a road bike having being measured by a good shop as fit it much more important and generally there is less scope for tweaking with seat posts and stem lengths etc (see the steve_b77 post and you will quickly see why).
Also, a lot of new road bikes (racing bikes) these days have very short HT lengths which are not really suitable for people with either poor flexibility or people who are not racing each weekend but just ride long weekend leisure rides. Look at a few geometry tables and you will see that HT length varies quite significantly across manufacturers for bikes with the same TT length even even excluding sportive specific geometries
For a 6 footer you seem to have relatively short legs but also not a particularly long reach? Finger in the air I would be expecting a fitting to be a 58cm but I can see why you may be thinking more 56-58cm.
58cm with a 120mm stem at a guess.
In my 20 year experience, I reckon the most important measurement is the head tube.
Ahead style steerers and stems mean that adjustability is limited, and a great stack of spacers is mechanically and aesthetically wrong.
Sort out how low or high you want the bars, then look at toptube and seatpost.
You can do an online bike fit calculation. I did one from competitive cyclist.
http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO
Takes a lot of measurements so at least you will have an idea & also info on different geometry setups. Will also sugest stem length etc.
But despite this - do go to a reputable shop & get a fitting, at least for your first road bike, it is important
