re my rear derailleur again

[rich p]

If the bike shop can straighten the alu rear hanger will it be fatally compromised or as good as new.

 

[Gerry Attrick]

Assuming it was only a little out of shape, it will be good as new. If it was severely bent then they should change it anyway with the same result.

 

[spandex]

If the bike shop can straighten the alu rear hanger will it be fatally compromised or as good as new.

You are right you can straighten alu hangers but the metal will be compromised and there is no way round it if it is just a mil or two out or 20mil out its still done for. If you bend it back it may hold or it may snap on you and dump your mach into your back wheel?

 

[mickle]

Aluminum can handle being bent once but bending it back to it's original shape really compromises it's strength. The inside radius of the bend develops tiny cracks when the bend is straightened out which lead to stress risers and subsequent failure. Much depends on the quality of the aluminum, how it was formed (ie, forged, cast or CNCd) it's thickness and how acute the bend. On a frame of such quality I would assume a high grade of aluminum so I reckon it's worth a try. Do you trust the workshop monkeys in your LBS?

 

[rich p]

I don't know if I trust them or not in a case of this kind. They've been good at more straightforward tasks but this may not be everyday for them.

The saver is that I insured the bike for a month when I took it to France on a plane so it is covered in theory by 2 days. For that to kick in i need the lbs to convince the insurers that it is potentially dangerous. We shall see. I'll tell the lbs the situation so that they aren't trying to do an unwise repair for my sake.

 

[Keith Oates]

In the long term it may be better to get a replacement and not have the doubt in the back of your mind!!!!!!!!!!!!!!!!!!!!!!!!!!!!!