When I started riding in the 1950s I rode a frame that was 4 or 5 centimeters bigger than I would use by the 1970s; it was the fashion of that time.
One of the reasons for this was that aluminum seat posts and handlebar stems were fairly new and were not as reliable as today, so by riding a larger frame we had less seat post showing and a shorter handlebar stem, resulting in less stress on those items. The big difference was the frame of the 1950s had very low bottom bracket height, as low as 9 1/2 inches. Because of this frames did not seem as big.
When I arrived in the US in 1979 it was as if I had gone through a time warp and landed back in the 1950s as far as the way bikes were set up and were being ridden. American cyclists at that time were riding larger frames than their European counterparts. The problem was these frames were designed with higher bottom brackets and I started hearing the term “Stand-over height.”
In my entire framebuilding career in England, this measurement was never once asked of me, and even today I could not tell you off the top of my head what the stand-over height is for and given size of frame I built.
To me stand-over height was something a bike store would do for a customer buying an inexpensive utility bike. They would pull out a bike; have the customer stand over it. If it cleared his crotch by an inch or two it would be close enough for the use intended.
When a rider got to the level of buying a top of the line racing frame, and he bought the size that fitted correctly, then stand-over height was not even an issue. If you could not stand over your frame then you definitely were using too large a frame. However, it was not the other way round; you did not talk about stand-over height first, or even mention it.
I am amazed that stand-over height is still being talked about today, I see it crop up all the time on the various forums; I see it asked of people selling frames on eBay.
The correct position on a road bike is all about efficiency. It is not just about a low tuck aero position; it is about getting maximum power to the pedals not only from the legs, but also from the arms, transferred through the back muscles. This means having the handlebars positioned low in relation to the saddle.
The problem arises when a person wants to use a road bike for more leisurely riding, and does not want that low position. They tend to use a larger frame to get the handlebars level with the saddle. However, a larger frame has a longer top tube, so any gain in raising the handlebars is lost because of a longer reach.
Now that road frames generally have sloping top tubes, they tend to run smaller than they did prior to the late 1980s. It is also a relatively easy matter to design a frame with a slightly longer head tube to raise the handlebars, and with clipless pedals, ground clearance is not such an issue. Maybe frame manufacturers should be thinking of lowering bottom bracket height for a non-racing frame.