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Carbon/Ti bonding(5 posts)

Carbon/Ti bondingbmb
May 16, 2003 11:13 AM
I've just ordered a Litespeed Siena, after much consideration. I swore that I'd buy a single material, standard geometry bike, but I love how the siena rides and it fits great. I just read the posting from katie1 whose Siena came "unglued." Anyone have experience with this problem?
Many timesalansutton
May 16, 2003 11:55 AM
I've seen lots of Ti/carbon/Al frames come unglued. Seems to be a design problem because not all bonded frames have this issue. I got hurt pretty bad when my Ti/carbon Specialized Ultimate came apart at the head tube. Also, my Al/Carbon ALAN frame came apart at the top tube. However, I've never seen a Calfee come apart, which it Ti/carbon.
She did crash it. nmBruno S
May 16, 2003 12:40 PM
re: Carbon/Ti bondingNessism
May 16, 2003 12:56 PM
My understanding is that the reason for failed joints is either 1) poor assembly quality (dirty joint and/or not enough glue) or 2) galvanic corrosion. Galvanic corrosion occurs when one material gives up electrons to the other material - forming a battery. This is a problem on Al to carbon joints due the differences in the materials electronegativity (propensity to give off electrons). To protect the joint, it is best to anodize the Al part before gluing since the coating forms a protective layer sealing the Al surface from corrosion. Carbon to Ti does not have this electronegativity difference so corrosion is less of a problem.

Bottom line is, Ti to carbon joint should be fairly reliable if assembled properly.

Good luck.

Ed
re: Carbon/Ti bondingslomo
May 16, 2003 1:09 PM
i've read that it is even better to wrap the aluminum parts with fibre glass (to act as an insulating layer) before the carbon gets laid up.

calfee does this with the luna pro's (what i ride currently) aluminum bb and head tube.