Where to get replacement derailleur

Hi Joseph

Practically there are only a few things that you need to match a rear derailleur to the one it's replacing. The first is the mounting point - check the mounting to the frame is the same. The other is the length of the cage - a short cage is typically used for road bikes and medium or long cage for mountain. The longer the cage, the bigger range of gears it can cope with, but the less precise the shifting is. As a rule try to stick to the same length cage, but if not, go longer rather than shorter (Unless you know what you are doing). try to stay with one for the number of gears as the chain, but it is not critical if its one either side. (i.e. an 8speed on a 7speed chain should be fine) but my ultimate advice is go a local bike shop and they can help you with buying a new derailleur in your price range or you can buy one here http://www.performancebike.com/bikes/Sub... for example but there are cheaper derailleurs out there though.