Correct Frame Size…

nigeve

I am 5’8” tall with about a 29 to 30 inch inside leg… Should I be looking at a 52cm frame..? I’m talking road bike here. My mountain bike frame is quite small and I have a high seat post but it looks like road bikes have bigger frames and lower seat posts…
I know I’ll need to try before I buy, but I’m just wondering what the ball park figure is that I should be aiming at…

Many thanks

Stuey01

52-54 probably. But you really need to try a few brands out.

laughingboy

You are a similar height to me, but your legs are slightly shorter than mine. For reference, I have bikes of both sizes mentioned.

But bike fit is not quite so simple, and a lot of it comes down to personal preference.

Legs, thankfully, are simple. Since the 52cm/54cm quoted in the frame size is the measurement of the seat tube, you should be okay with either - you just need to raise or lower the saddle to accommodate your legs. (Before we move on from quoted frame sizes, the other thing to bear in mind is how high you want your handlebars. Basically, a larger quoted frame size can mean that your handlebars are higher relative to the saddle.)

Then it gets more complicated. Another really important measurement is the top tube length, as you can only do one of three things to adjust this.
1/ You can raise or lower your handlebars, which affects how tucked/comfortable you are and thus your aerodynamics.
2/ You can replace your handlebar stem with a marginally shorter or longer one - but large adjustments here can adversely affect the handling of the bike.
3/ You can move the saddle back and forward - this shortens/lengthens the effective top tube length, but it also shifts your centre of gravity on the bike, which affects how stressed your back, shoulders and hands will get.

To summarise - I suspect that most 52cm or 54cm bikes will be roughly the right size for you, but there is no substitute for a test ride and a lot of post-purchase micro-adjusting to get really comfortable.