Help with modern road bike sizing

[Peachy!]

Hello & Happy New Year!

I'm looking for help regarding modern road bike sizes having never owned/ridden one produced in this century!
Now I do understand that a more modern bike tends to have a bit more seat pin so they don't necessarily match up with older steel sizing, and although I'm 6'1" I have quite a large inside leg (34") but a short reach so here's what I ride;
My 80's racer - 24" (61cm) I'm a bit perched with the seat low down but not rammed and I need a short reach stem.
My 60's Tourer - 23" (58cm) Probably my most comfortable with a tall seat post and normal stem.
My 50's Vintage - 22.5" (57cm) perfectly comfortable on the very few sunny flat miles that I ride it.

So I've heard that you should choose a size down when looking at a modern frame, I guess because the seat post can make for a wider variation?
The 2012 carbon bike I'm looking at comes in three sizes; 52cm, 55cm & 58cm. so should I be looking for a 55cm version?

Any help would be much appreciated.

 

[Woz]

It's a nightmare due to semi-sloping or sloping top-tubes now. The traditional seat-tube sizing method means very little.

My advice would be get the geometry chart and select a size based more on effective top-tube comparisons.

 

[Peachy!]

It's a nightmare due to semi-sloping or sloping top-tubes now. The traditional seat-tube sizing method means very little.

My advice would be get the geometry chart and select a size based more on effective top-tube comparisons.

Where do I get a geometry chart? Is it a generic thing on the tinternet or something bespoke for each bike?

 

[d8mok]

I’d say a 58 would suit you (unless it’s a dogma)

 

[Mike-p]

I can't advise but I'm very similar proportion. I used a saddle to pedal measurement which might translate more easily. Are your frame sizes quoted ctt seat tube?

 

[Woz]

Where do I get a geometry chart? Is it a generic thing on the tinternet or something bespoke for each bike?

Each manufacturer should produce a geometry chart for their line up. Typically towards the back pages in the catalogues when printed matter was in vogue, but I digress. You would need to know the make, model and year to help find it for older stuff.

 

[Peachy!]

I can't advise but I'm very similar proportion. I used a saddle to pedal measurement which might translate more easily. Are your frame sizes quoted ctt seat tube?

My old sizes are Centre BB to top of seat tube. I'm not sure what the catalogue quoted sizes represent (the 52-55-58cm)
I've found a 2012 55cm version of the bike I'm after so I'm going to try before I buy.

 

[Peachy!]

So after a little Googeling I found this guide; I'm 185cm so I can assume I'm in the 182-192 window. If the quoted 52,55,58 are referring to "seat tube C/C it's a fit I guess?
I think I definitely need to go sit on it.

 

[d8mok]

Are we talking seattube sizes?


Modern road bikes are sized in Top tube aren’t they?

Hence me saying 58 which is bang on that table.

 

[Peachy!]

Are we talking seattube sizes?


Modern road bikes are sized in Top tube aren’t they?

Hence me saying 58 which is bang on that table.

I've no idea, the bike is from 2012.