technical question about a cannondale slate frame manufacturing detail

[bicycletricycle]

I was checking out a cannondale slate recently and noticed a nice reinforcement detail on the chainstay disc flat mounts. Hard to see how they managed the thin reinforcement around the flat mount disc mount holes. It looks like a thin patch of sheet metal was added around the through holes which is hard to do in aluminum. The whole area is lacking the evidence of big aluminum TIG welds. I am guessing the back part of the stay is cast with all of the disc mount details in it and then welded onto the hydroformed tube and ground so that they appear to be one piece.

what do you guys think?

http://i975.photobucket.com/albums/ae236/bicycletricycle/8362187_first-impressions-cannondales-slate-front_ta0b9b94_zpsz05pxxjp.jpg (http://s975.photobucket.com/user/bicycletricycle/media/8362187_first-impressions-cannondales-slate-front_ta0b9b94_zpsz05pxxjp.jpg.html)
http://i975.photobucket.com/albums/ae236/bicycletricycle/Cannondale-and-Fabric-2016-product-launch-CAAD12-rotor_zps6gb69obn.jpg (http://s975.photobucket.com/user/bicycletricycle/media/Cannondale-and-Fabric-2016-product-launch-CAAD12-rotor_zps6gb69obn.jpg.html)
http://i975.photobucket.com/albums/ae236/bicycletricycle/1435618474240-xliicf0c8s8a-630-354_zpshnqqy9ng.jpg (http://s975.photobucket.com/user/bicycletricycle/media/1435618474240-xliicf0c8s8a-630-354_zpshnqqy9ng.jpg.html)

[David Kirk]

My money is on bonding.

dave

[bicycletricycle]

i was considering that, however, those through holes intersect the tube wall, which would require the tube getting partially slotted and then only the bonded mounts would be holding the tube back together.

bonding is pretty amazing these days, I am sure it would work for a while but it would seem to be a little risky in the long term.

[cadence90]

The reviews I read indicate that your first assumption is correct:

"The rear end of the Slate incorporates a new flat-mount disc brake interface and 142x12mm thru-axle dropouts. Cannondale produces the disc mount as a wholly separate aluminum bit that supposedly weighs just 8g, and then quite cleverly brazes it in place for an ultra-strong union to the chainstay."

[zank]

Ha. I was going to say brazing.

[mike mcdermid]

one thing the automotive industry does well Aluminium brazing

Lots of radiators and intercoolers , air con connections all aluminium all brazed very reliable in service (unless you get one that leaks)

but sure enough you can braze and then heat treat and the frame hardly knows its there

[bicycletricycle]

That's interesting, I was under the impression that aluminum brazing was kind of garbage , I think brazing is the answer.




one thing the automotive industry does well Aluminium brazing

Lots of radiators and intercoolers , air con connections all aluminium all brazed very reliable in service (unless you get one that leaks)

but sure enough you can braze and then heat treat and the frame hardly knows its there

[Peter B]

Stoemper offers an internal cable routing option on their AL bikes that uses brazed stops.

[christian]

These types of threads are why, after 13 years, I keep dropping in. Interesting!

[bicycletricycle]

Hmmmmmm

This aluminum brazing in frames has snuck up on me.


As a side note, those cannon dale slate frames are nice, a little suspicious of the grazed on disc mount.