Ok, I'm a little confused and need some clarity please. I have a TREK road bike that I use for Triathlons. My front derailleur broke and will not shift. I want to replace it, but all I can not seem to find one for a 21 speed. Why? What am I missing? Am I looking for the wrong thing? What should I look for? Are all front derailleurs the same? universal? Help Please. Thanks
Derailleurs are designed for the number of chainrings, not total speeds. You need a triple front derailleur. Google "install front derailleur" to learn what you need to know. sheldonbrown.com and parktool.com offer the best advice.
It also should say "7 speed" (though 8spd will be fine, too). At some point in time people stopped talking about the total # of speeds and started to talk about the cassette (rear) only... Check that the dérailleur is specced for the size of the small and large chain ring (# of teeth)
Thanks guys, I appreciate it. You were a lot of help and I am now more educated today than I was yesterday. Off to shop for a new derailleur. Thanks again.