I started riding as a kid in the UK in the 1950s and remember that the front brake was always on the right side. Decades later, when I got back into cycling in Canada in the late 1970s, I found that te bikes being sold had the brake positions reversed. I just put it down to ignorant LBS mechanics and always switched my bikes. Over the years this situation always bugged me. The more I tried to rationalize it, the more confused I became. It seems that the "left front" convention was decreed in North America by the U.S. CONSUMER PRODUCT SAFETY COMMISSION based on inexperienced riders feeling that the rear brake should be the primary brake. This probably harks back to the first half of the last century, when balloon tired bikes with coaster brakes were the norm and front brakes were unknown. The safety aspect for inexperienced riders is probably a big factor too because our safety laws are designed to defeat Darwin. I went over the handlebars only once as a kid due to grabbing the front brake too hard and I never did it again. Sheldon Brown was absolutely right when he said: "The theory that seems most probable to me is that these national standards arose from a concern that the cyclist be able to make hand signals, and still be able to reach the primary brake. This logical idea is, unfortunately, accompanied by the incorrect premise that the rear brake is the primary brake." Considering the rear brake as the primary brake is flawed logic coming from bureaucrats, not experienced cyclists.

The thing is, until the advent of aero brakes in the early 1980s, it was a quick, simple job to switch front and rear brakes on a road bike. After that, it became a much more complicated, if not impossible job. Today you'll only see people with vintage road bikes switching brakes around.

As for which countries put brakes on which side before being influenced by the U.S. CPSC, it's not entirely clear. Looking at pictures from old classic road races, one sees a mixture, not necessarily connected to the rider's country of origin and on which side of the road they drive. Since the brake cables could be switched from side to side, I started searching for pictures of roadsters with rod brakes. Since the rod brake linkages can't be switched from side to side, these pictures would indicate the original brake location intended by the manufacturers. These were popular in England in the first part of the last century and are still very popular in many Third World countries. Invariably these roadsters had the front brake on the right, except on a few rare French bikes where I found a couple that were the opposite. Based on tis observation, I would conclude that the original position for the front brake was on the right.