Welding on snapped bike???

Question

okay so i snapped this cheap mongoose in half its an aluminum alloy frame and i need to reweld it but was wandering what is needed in order to do it properly...///// also if u know how to make it stronger please let me know its just a 20inch dual suspension bike....

Answer 1

You can't weld aluminum unless you also have the facilities to re-anneal and re-temper the frame.

If the frame broke it is probably because it was used for something it wasn't supposed to be used for... those 20" FS Mongooses are only for 'looks'. They should only be ridden on smooth roads... no tricks, no jumps, no ramps, no abuse.

Throw the bike out and start over.

Answer 2

by the time you buy all the welding equipment, it would be cheaper to replace that bike with a modest upgrade from your local bike shop. bikes from toy shops aren't worth the major repairs.

Answer 3

Just get a new frame. Or a new bike! Not only is welding aluminum tricky, but to do it right you have to heat treat it afterwards or it will just break again. Welding makes the aluminum weak in the area near the puddle, and heat treating restores the strength by realigning the 'grain' of the metal. Heat treating involves heating the frame up to very high temps and cooling it at a specific rate - beyond the capabilities of most normal people.

Aluminum has a finite stress cycle. Simply put, if it flexes at all, it will eventually break. If you are putting a lot of stress on your bmx by jumping, wheelies, etc, then a steel frame would probably last longer.

Answer 4

Aluminum is not a forgiving material and welding aluminum is not a trivial task.  Frankly, there was probably nothing wrong with the design of your bike.  No doubt, it was poorly welded resulting in a weak joint.

Before you take on this bicycle repair yourself, you need to go take a welding course.  TIG welding is used for most high quality aluminum work.  So, your goal should be to master TIG welding of aluminum.  In the meantime, you might want to find a local bike builder to repair your frame.   Short of a bike builder, a race car shop or body shop that specializes in aluminum may be able to help you out.

Hope this helps.