Originally Posted by
Bogey Speedwell
Haven’t seen much for clarification on type of geometry on vintage bikes, but this may be do to my lack of knowledge. When I utilize a geometry comparison tool, it seems the difference is negligible. Other than the handlebars being slammed, I’m not sure I’d notice. Currently I purchased my Topstone which falls under the endurance category, and this position seems to suit me the best.
A couple clues that are a rough indication of the geometry of a frame are the tire clearance and wheelbase. You can spot this by looking at how much space there is between the rear tire and the seat tube, and to some extent, the space between the front tire and the downtube. A bike built with touring in mind will have a longer wheelbase, around 42 inches or more, so you can fit your whole hand between the tire and seat tube. They usually have a more forgiving ride over rough roads. Older racing bikes were built with similar geometry because of the terrain the races were run over. A lot of people like these bikes for long day trips or light touring. Starting in the 1980s, bikes built for racing usually had a shorter wheelbase, around 40 inches. There is just enough space to fit a finger in between the tire and seat tube. They usually have quicker handling and a stiffer ride.
Another thing to look for is the height difference between the saddle and the tops of the handlebars. Like you, I prefer the endurance set-up, with the bars at or just a hair above saddle height. If the frame is too small, with a lot of seat post showing, you will have a harder time getting the bars up where you want them.
These aren't hard and fast rules, just some things to help filter out bikes that aren't what you're looking for.