what did I do wrong?

[kiwi girl]

Its interesting that, as noted in the Sheldon Brown link different countries set it up different ways. All my bikes came with the front brake on the right and, I guess because I am right handed, it is natural for me to use the front brake more

[Geonz]

Part of my effective cycling course was practicing those "throw your butt back, brace your arms and slam on the brakes" stops (as well as looking back without weaving and the "lean right to turn left" to get around an obstacle move) in a big parking lot. Everybody in the class was an experienced rider, but it still didn't hurt to practice.
My bike's big rear end is not likely to go up into the air without extreme provocation, but it can fishtail if it's wet. My current rear brake is so noisy that it inspires me to hit the front first unless I'm in town and want to be sure to announce my presence at any intersection with a pig-like squeal. Interesting that SHeldon Brown says I need to use those back ones anyway.

[DebW]

My current rear brake is so noisy that it inspires me to hit the front first unless I'm in town and want to be sure to announce my presence at any intersection with a pig-like squeal. Interesting that SHeldon Brown says I need to use those back ones anyway.

Sorry for the topic deviation, but noisy brakes can often be silenced by toeing in the brake shoes. Some brakes are noisy no matter what, but sometimes the pad angle makes a big difference. The pads should hit the rim either flat or with the front edge contacting first. If this isn't the case, take a crescent wrench and fit it snugly on the brake caliper just above or just below the pad and bend gently. Unless you prefer your dual purpose brake/horn, which has its advantages.