I queried this for a while as well, then just bought one. I found both my bikes needed adjustment, as well as a couple of friends. My friends gave me beers for the use of the tool.... so I guess its already paying for itself.Philo Beddoe said:
As others have mentioned it has its limitations with certain materials. I have one for my DH bike which doesn't have replaceable hangers. The frame is made of aluminium however and only good for a few straightenings if not severely bent. Also being aluminium, replaceable dropouts may not take being bent back well without breaking. They are about $25 each. The tool is about $45 and works best on steel frames.Philo Beddoe said:
I've never seen a carbon fiber derailleur hanger so I can't speak to that. But I have used the tool under discussion here to align steel, aluminum, and titanium derailleur hangers on my personal bikes with nary a problem.Bikinfoolferlife said:especially when you have what's needed. I like having tools and working on bikes, and while I don't use this one a lot, it's great when you need it, as well as great if you can use it. Limitations to keep in mind that certain materials other than steel may not work well with this tool; aluminum, carbon and titanium frames/dropouts you may have success with but don't count on it, you're more likely to do damage, steel is best material for this tool.
The tool being discussed here is for aligning derailleur hangers. But since you brought it up, just as important to have access to or own -- for other reasons -- is a pair of dropout aligning tools, commonly called "H" tools after the Campagnolo designation.Philo Beddoe said: