How has road bike geometry changed in the past 30+ yrs?

[smontanaro]

I only have vintage road bikes. Perhaps my newest bike dates from the early 80s. I keep an eye on the PSA Good Deals (https://forums.thepaceline.net/showthread.php?p=2511432) thread in hopes of someday stumbling on an early Serotta in my size.

There was a link to a Litespeed Ti - size XL (https://sandiego.craigslist.org/ssd/bop/d/chula-vista-litespeed-titanium-ti/6832167368.html) which I clicked on just for grins. The CL ad might just have been wrong, but it didn't look "XL" to me at all. From the ad copy: "The size is XL. The seat tube measure 56-57cm from center to center. The top tube measures 58-59cm. I am 6'1"(with short legs) and the bike fits me."

By my way of thinking, that can't be "XL". Maybe I'm more normally proportioned, but in the vintage bike world I play in, a 56-57cm seat tube would normally be accompanied by a 56-57cm top tube. I'd only expect to see a top tube longer than the seat tube for pretty small frames (54cm or less). The seller doesn't indicate the frame was custom, so I'm guessing it was just a standard production frame. Is this long top tube, short seat tube setup common now?

[Black Dog]

I only have vintage road bikes. Perhaps my newest bike dates from the early 80s. I keep an eye on the PSA Good Deals (https://forums.thepaceline.net/showthread.php?p=2511432) thread in hopes of someday stumbling on an early Serotta in my size.

There was a link to a Litespeed Ti - size XL (https://sandiego.craigslist.org/ssd/bop/d/chula-vista-litespeed-titanium-ti/6832167368.html) which I clicked on just for grins. The CL ad might just have been wrong, but it didn't look "XL" to me at all. From the ad copy: "The size is XL. The seat tube measure 56-57cm from center to center. The top tube measures 58-59cm. I am 6'1"(with short legs) and the bike fits me."

By my way of thinking, that can't be "XL". Maybe I'm more normally proportioned, but in the vintage bike world I play in, a 56-57cm seat tube would normally be accompanied by a 56-57cm top tube. I'd only expect to see a top tube longer than the seat tube for pretty small frames (54cm or less). The seller doesn't indicate the frame was custom, so I'm guessing it was just a standard production frame. Is this long top tube, short seat tube setup common now?

That is not unusual. Even with level top tubes, having equal length ST and TT is not common due to varying lengths of Head Tubes that have integrated headsets or external headsets etc. Not a custom frame in the ad and if it fits you and you are ok with cyclocross geo then you will be ok.

[Mark McM]

One thing that's changed since the "classic" era of road bikes is that seat tube length is no longer closely tied to the rest of the frame dimensions. Gone are the days when you could know a frame's "size" just by the seat tube length. This is a large part of the reason that frame sizing has largely moved on to using Stack and Reach to indicate frame size, rather than seat tube length.

And to your direct question, yes, it is common today to have a seat tube length significantly shorter than top tube length; top tube length is a generally a better indicator of actual frame "size".

[choke]

By my way of thinking, that can't be "XL". Maybe I'm more normally proportioned, but in the vintage bike world I play in, a 56-57cm seat tube would normally be accompanied by a 56-57cm top tube. I'd only expect to see a top tube longer than the seat tube for pretty small frames (54cm or less). The seller doesn't indicate the frame was custom, so I'm guessing it was just a standard production frame. Is this long top tube, short seat tube setup common now?Your way of thinking is pretty much correct when the bike has a level top tube....but when the top tube is sloped then the seat tube length will almost always be a fair amount shorter than the top tube length.

[Ronsonic]

My more universal size comparison system is effective top tube and head tube. Stack and reach are more precise but rarely published. They largely relate to ETT and HT so it's a pretty good stand-in for most frames.

I do notice that "Large" these days isn't quite as large as it used to be. But that's just a sales word.

[pobrien]

[QUOTE=smontanaro;2511764]I only have vintage road bikes. Perhaps my newest bike dates from the early 80s. I keep an eye on the PSA Good Deals (https://forums.thepaceline.net/showthread.php?p=2511432) thread in hopes of someday stumbling on an early Serotta in my size.

I like my 30 odd year old bikes as much as my c50 or c59 for handling though I do appreciate the campy 11 speed drive trains available now!

they are all good bikes. I would be torn to have to pick just one bike to ride. It could be my Merckx Corsa or the c50 or the c59, depending on the day.