Is 6063 aluminum tubing suitable for making a bicycle or motorcycle frame? is it strong enough?
6063 aluminum tubing
Apr 06, 2008
8 Replies
This job requires much more data and a professionally performed FEA analysis. It depends entirely on the wall thickness, weld sizes, and other factors.
The safe answer is no.
6061T6 - maybe - depending on size adn wall.I was thinking with enough outer diameter and wall thickness maybe
6063 will be good enough and still be lighter than using steel tubing.
Why 6063, and not the more common 6061? Do you happen to have a stock of
6063?Bicycle frames have been made out of 6061. I had an Italian Allegro aluminum frame on my sprint bike in the late '60s. It was too flexible, but aluminum framed bikes have come a long way since then. They generally use larger-diameter tubes to overcome the lack of stiffness.
I don't know about motorcycle frames. Spaceframe racecars have been made out of 6061, and the Bobsy sports-racer of the 1960s was very successful with an aluminum spaceframe:
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However, aluminum has little or no advantage over steel in a spaceframe application. If the structure's tubes are loaded only in tension and compression, as in a spaceframe, aluminum's properties result in a chassis that weighs about the same, is roughly as stiff, and roughly as strong as a steel one. But it's several times harder to weld and it costs several times more.
Aluminum shows its advantage in structures that are subject to bending, rather than to tension/compression. A bicycle frame does have bending loads. A motorcycle frame generally has some, but not always.
So you want to think carefully about why you'd use aluminum. Most engineers who have approached it have decided it's more trouble than it's worth, with rare exceptions.
-- Ed Huntress
okay thank you!
i do want to use 6061 but there aren't too many suppliers of aluminum alloys in my country and I just found this one that sells 6063 alloy products.
either 6061, 7075 or 2024 alloys but then it's really difficult to look for suppliers here.
i guess i'll have to look around some more.
Except for 6061, those other alloys will require lugs and adhesive assembly, rather than welding. 7075 can be welded but it loses its corrosion resistance. On 2024, you won't get a satisfactory weld, and the tubes may crack. And the welding on 6061, or any weldable aluminum alloy, almost has to be TIG (GTAW) when you're welding tubes.
All in all, you need a really good reason to make a tube structure out of aluminum, rather than steel.
-- Ed Huntress
Try Steel.
Some of the specialty bikes are made with specially forged or formed flanges at each frame join point, fluxed and 'preforms' of wire solder placed inside the lugs, clamped into a jig, and the whole frame is brazed in one shot in an industrial oven...
But when you consider all the variables that have to be controlled and gotcha's conquered, that's an even trickier method than TIG welding - useful only for production shops that get lots and LOTS of practice at it.
For a low production shop or a low-skills country, and if you insist on using aluminum tubing: Buy excellent welding gear (Miller) and proper safety gear and accessories, and have a few staffers sent to a tech school and get /lots/ of hands-on practice time (buy material they can use for practice coupons) to learn how to TIG weld properly and well. It is an art that takes time to perfect.
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