Originally Posted by staehpj1

I have had them on a couple bikes and really didn't care for them. There were several reasons not all of which apply to every size frame. These are all based on my experience for my bikes, my fit choices, and so on, so YMMV. Some of these are touring oriented and some more racing/performance oriented.

1. I tended to bump them out of the desired gear accidentally while riding, usually while standing to climb.
2. They tended to get bumped out of gear when leaned against a wall or whatever when I took a break to get a drink or snack or shop or whatever. Then when I started out it wouldn't be in gear.
3. Once in a while I banged up a knee or thigh on them.
4. I actually found them less handy to reach than down tube shifters which were the other popular choice at the time. People often complained that they had to reach further down to reach down tube shifters, but on my bikes they were at the exact same height given my frame size and preferred bar height. If I wanted to shift the front and back i could even do both with only one hand going to the shifters.
5. I had a few buddies who were jerks and liked to reach over and shift them for me