pinky

Hey all, anyone know if its possible/safe to repair a cracked front braze-on for a derailler on an Al frame??

Thanks,
jw

sch

In theory yes, in practice not a good idea as it will change the character of the metal enough that the frame will be at risk. Assuming the tubing is not some outre size or shape, a real assumption with some bikes, it would be best to grind off the residual flush to the surround and use a clamp on. Al frames tend to be heat treated after assembly and it is not possible to do this on a non industrial basis. Besides, finding high quality aluminum welders is not straight forward. There are a lot of bozos out there welding.
Steve

sydney

Bolt on ones are alot easier to remove.

pinky

Its an aero seat tube, so clamping isn't going to happen. Sounds not good.

sch

Figures. Well second option would be to google up some frame building sites and look for a bit that most resembles the part that broke off, order one, and file down the rough parts of the broken bit and drill and tap several holes to bolt and epoxy the two bits together. The FD will be a few mm off of where it should be but should be workable. The thickness of the OEM part that is welded to the frame should allow a fine thread flat head screw, say 6-32 or 4-40 to be used. Size of the part should allow 3 or even 4 screws to be used. Real hassle would be matching the curve on the two parts-a bit of blacksmithing there. Worth a try over a new frame or buggering it with a bad weld.
Steve

sydney

I'd get some advice from a a real frame builder.