Bike Size

[Yorkshirelad92]

Morning All

I’m currently in the market for either a complete or frame and fork set project.

Im looking at a Peugeot road bike frame maybe a Dawes I'm not sure yet. Anyway I’m questioning what size would be a starting point for me. I’m 5ft 6 with a 28” inside leg length.
The older frames seem huge compared to modern ones. Well visually they look it anyway.
Any advice be much my appreciated thanks
Tom

 

[non-fixie]

Most of the vintage frames I ride measure between .70 and .72 times my cycling inseam. With my 35" inseam that means 62 to 64 cm frames (center-to-top).

With a cycling inseam of 28" I think you'd be looking for a 50-51 cm frame.

 

[bikeworkshop]

Vintage frame sizes were usually given in inches in the UK market.

Parallel toptube means there's only a few inches of post exposed.

The frame size can be quickly identified from how much headtube is between the head lugs, which is handy as you don't need the built bike to judge the fit.
Toptubes usually had a standard proportion to the seattube length, so if you get the"height" right, the length should be right too.
Here's a 23":
And here's a 21":
You'd probably be 20 to 20&1/2", (room for a finger between the lugs)
You might get on a 21 ok.
Minimal clarance used to be quite normal

 

[Yorkshirelad92]

Hi
Thanks for the advice big help. I was thinking around a 20” or 50cm or there abouts anyway but I’ll try choose carefully and see what I can sort out.

 

[Yorkshirelad92]

Am I right the stand over height on older bikes is important and if that’s somewhere near right then the length should be ? I guess longer or shorter stems can be used.

 

[non-fixie]

The frame size can be quickly identified from how much headtube is between the head lugs, which is handy as you don't need the built bike to judge the fit.

True, but only for bikes from the same era and built for the same wheel size. After the mid-eighties fork clearances for tires and mudguards became much smaller on racing bikes, and steerer tubes became taller as a result.

A similar effect can be seen on bikes designed for smaller wheels, such as 650B. To those used to 700C or 27" wheels those frames look bigger than they are.

 

[Jez Nemeth]

Hijack question -apologies in advance Yorkielad.

Q? So what is the recognised way of measuring old frames?

-some seem to measure from bottom of BB to top of top tube -other's centre of Top tube...always seems to be a bit of guesswork when buying a frame.

 

[bikeworkshop]

Different manufacturers followed different conventions.
I'd say centre bb to top of toptube has become the most common

 

[Jez Nemeth]

See, I'm the same -Centre BB, top top tube...
But like you say -different makers, and to nearest 1/2" round up too.

23" used to be standard men's size 58-60cm -and most common on pre-70's bikes certainly -pre-war smaller frames dominated 20", 21", 22" and half sizes in between. Beyond that up to 26" was special order.

 

[Yorkshirelad92]

Hijack question -apologies in advance Yorkielad.

Q? So what is the recognised way of measuring old frames?

-some seem to measure from bottom of BB to top of top tube -other's centre of Top tube...always seems to be a bit of guesswork when buying a frame.

No please hijack away I’m intrigued as well there is so many different ways.