Aluminum mountain bike rear suspension TIG weld repair

[Grizzly1944]

Jakeru,

The reason that it broke in the first place is because that the aluminum most likely wasn't heat treated and aged after it was welded at the factory. Whenever you weld a piece of metal it is annealed because it was heated up to the melting point. This weakens it as in this case. The high end bicycle makers will heat treat and age aluminum to bring it back to it's original strength.

I have experience building bike frames and could never figure out why these makers choose aluminum over chrome moly steel. The Aluminum tubes have to be almost twice the thickness of steel to retain the same strength and are heavier than a well built steel frame. Steel tubing is so much stronger that heat treating is not required after welding.

I just wanted to make you guys aware of some of the hazards that can arise when welding aluminum and magnesium.

Best regards!

[SeanMurphy265]

The issue is weight and that is why they chose aluminum. I realize we are not talking about much weight maybe a pound or two. The lighter the bike the less drag it will have.