I’m looking at buying a first road bike. I’m 6ft and ride a large stumpy for XC and a medium Glory for DH which I find a little short. The stumpy is a 19″ and i’m looking at a large scott speedster. The bike is 56cm which I think would be perfect but a mate has suggested I might need a 58cm. What do the STW Roadies think?

Fit is crucial on a road bike – you spend a long time sat/ceased in pretty much the same position. Getting it wrong can be painful and expensive.

Only way to see is to sit on one and try it out – and sizes vary by manufacturer and geommetry – I’ve had road bikes in 48, 52 and 54 sizes over the years.

I think you should go to a good shop and not rely on anecdotal sizing evidence from people who are not the same proportions and flexibility as yourself.

I think you’ll be ok on either, my eldest has outgrown his 54 speeder he’s 6ft….as said above, best to try them..

58 comfort fit, 56 a race fit, a bit more bum in air.

I used the Competitive Cyclist fit calculator and it was pretty much spot on for me.

sizes vary by manufacturer and geommetry – I’ve had road bikes in 48, 52 and 54 sizes over the years.

This.

top tube length is important for fit, not seat tube (htough its how manufacturers “rate” fraem sizes). My 52cm Lapierre has a (slightly) longer TT than my 54cm Orbea, which has the same as the 55cm Bianchi I borrowed (all 550cm effective TTs).

57cm?

As above, 58cm will have a longer top tube,higher handlebars and a reasonably relaxed fit. 56cm will need a longer stem for the same reach (bottom bracket to handlebars) with more weight over the front. For a first roadbike, go with the 58cm. You may,however find that you want a 57cm. In which case another brand may be a better fit.

56 or 58. both will be ok.

2cms is the width of your thumb, and really wont make much difference to an average person

fwiw i would go for a 56 TT frame iiwy

2cm will make a difference, that’s why stems come in different lengths and I swapped from a 120 to a 100 on one bike. Do you wear shoes a size too big as well?

Of course seat tube is important im 6ft 4 if I rode a small frame the bars would be way to low my 24 to 25 inch frames have about 9 inches of seat post out and long stems I would look like I had outgrown anything smaller