ChrisEeeSee

Before I drive a few hours to buy an older, steel road bike, I wanted to make sure the sizing is the same as newer bikes with sloping top tubes and such. I saw something somewhere suggesting a 56 cm bike was for someone 5'4"-5'7", and thought that can't be right. Can anyone confirm that if I ride a 58 cm "newer" road bike, that I would also ride a 58 cm older, steel bike, minus the small differences from brand to brand?

Puget Pounder

There aren't "small" differences from brand to brand. A 58 in one brand can be way different than a 58 in another. There is also no difference between how bikes are sized now and back then. Bike sizing has always been non-standardized.

The best quick-and-dirty method is to match top tube length, but even that can be a bad approximation since it ignores other features of geometry.

ChrisEeeSee

Thanks!

repechage

All true. In this XS/S/M/L bike sizing world of today, a bit of a Wayback machine trip is in order. Many if not most bikes prior to the 80's were measured from the center of the bottom bracket to the top of the top tube, (with some minor measure point variations) In the 80's a "center to center" measure to the center of the top tube was begun by the Italians and it grew. So, with a 1" top tube the difference is significant for some, as in general a bike gets longer as it gets bigger.

Top tube measure has thankfully been center to center and almost always along a nice Level top tube.

Size can also vary depending on athleticism and intended use. All else being equal, a slightly larger frame makes it easier to set the bar height close to or at the saddle height without a long quill stem, but rarely are all things equal.

Road Fan

There are other vintage variations: Masi sized bikes by seat tube length from BB center to top of seat lug. About 1.5 cm longer than c-c.

I think c-c was common at least in Italian bikes long before the '80s, but considering I'm not Italian nor did I understand sizing back in the '60s, I can't really say.

wrk101

1. Most sellers get size wrong, often way wrong. So being able to eyeball size from pictures is an important skill to avoid needless trips.

2. Myself, on modern bikes, I am a size or two smaller than vintage bikes.

+1 Then you have the whole center to center, center to top issue.

I would be shocked if a 58cm bike fit someone 5-4 to 5-7.

wintermute

+1 on all of these. Also, once you are able to check out the bike in person, I typically just go with the ol' standover with about 1" to spare rule on "old" road bikes.

20grit

You can't base things on overall height either. I'm just shy of 6'-3", but I'm mostly torso. I comfortably ride 60/61 cm frames but need a 130mm stem in most of them. People with longer legs, but similar height can ride 63 cm frames with few problems, and run a shorter stem.

You need to know inseam length and your reach/bar height comfort level.

due ruote 

If you want C&V folks to opine about what size older steel frame bike you should ride, it would probably be more fruitful to state your height, floor-pubic bone and wing span measurements rather than tell us what size modern bike you ride. Well, for me it would, anyway.

dbakl

Back in the day, the typical advice was to pick a bike you could stand over flat footed without crushing your hoo-haws. To some extent, top tube length can be adjusted with stem length and seat postion. Many classic frames were built square, seat tube and top tube more or less the same.