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-   -   Bonding steel/aluminum (http://www.bikeforums.net/framebuilders/389472-bonding-steel-aluminum.html)

CrimsonKarter21 02-18-08 07:02 PM

Bonding steel/aluminum
 
Okay, so I know a guy on my team who's willing to give me a pro deal on a custom frameset. I want a nice track bike, oversized tubing, PAUL track-ends, severely sloping top-tube while still maintaining two 700c wheels, and an "integrated" seatpost.
I remember seeing on Isaac carbon fiber bikes that their top-of-the-line model, the Newton (I think) was all carbon fiber, but had aluminum seatstays because they're a lot stiffer and not too much of a weight penalty.

Can I have bonded aluminum stays on a steel frame, or should I just go safe and have it all steel?

Hocam 02-18-08 08:18 PM

The problem with bonding two dissimilar metals to each other is that their coefficients of thermal elasticity are generally very different, as is the case with aluminum and steel. What this means is that at temperatures different from the original bonding temperature, the bond will be under stress simply from the two materials expanding or contracting away or towards each other.

So yes, you could probably do it with some kind of epoxy but who knows how long it will last? Besides, there are plenty of oversized steel chainstays available.

maddog17 02-19-08 05:18 PM

sounds like an interesting idea, but why would you want to bond alu to steel anyway? i would think you would want the frame stiff so how would you match a thicker alu end to a slimmer steel end? that would mean the lug would have to be 2 different sizes at each end and i'd assume you would have to either make it yourself or buy a big lug and trim it down for the steel side. so to make things easier, go all steel.

flatlander_48 02-19-08 06:07 PM

Quote:

Originally Posted by Hocam (Post 6189426)
The problem with bonding two dissimilar metals to each other is that their coefficients of thermal elasticity are generally very different, as is the case with aluminum and steel. What this means is that at temperatures different from the original bonding temperature, the bond will be under stress simply from the two materials expanding or contracting away or towards each other.

So yes, you could probably do it with some kind of epoxy but who knows how long it will last? Besides, there are plenty of oversized steel chainstays available.

Expansion...

Hocam 02-19-08 06:22 PM

Thanks :)

CrimsonKarter21 02-19-08 09:14 PM

Okay, thanks for the information. I guess I need to learn a little more about metal!

Arab T.R. Wrist 02-19-08 09:21 PM

Electrolysis would be an issue here also, non?

Fred Smedley 02-22-08 04:12 PM

Miyata did it for years and mine's still holding tight.

jeffz 02-22-08 05:16 PM

Raleigh did it as well. I think they called it "Technium".

NoReg 02-22-08 09:37 PM

If I had to do it in my garage, I would just weld on short steel tubes that would sleeve over the aluminum, and then epoxy those suckers in there. Give myself at least about 3-6 diameters of penetration and I might get out alive. Postcure the epoxy and use microballons.


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