I have to thank Bikehugger for taking time off to visit HED Cycling's HQ in Shoreview, MN this week. He has brought back pictures and commentary. Click here to see his HED Flickr slideshow.
At the other end, thanks also to Manantan of Pez Cycling who, in his usual lust for ornamental bike parts and mega resolution picture taking, promptly visited ZIPP's Production and R&D facility in Speedway, Indiana. Click here to read that article detailing his tour.
Just from reading the commentary by both authors and seeing pictures, I noticed an interesting aspect of the rim-shell bonding process.
HED glues the carbon shells that are made in Iowa to the rim at their HQ in a special setup. It doesn't seem to be anything more.
HED Gluing Process (Courtesy BikeHugger)
ZIPP actually co-molds the rim and shell together in their proprietary process that yields a structurally stronger bond at the interface. This is partly where your dollars go.
I'm not in a position to give you a textbook account of the co-molding process because that is not my background, but readers will be aware that this is used not only in wheels but in Bell Helmets (see my past post on How Helmets Are Made), and high end bicycles such as the Gary Fisher HiFi Pro Carbon MTB (see link) and the Cannondale Six 13 (see Six 13 co-molding with Al lugs and carbon tubes).
If any of you are experts in composites and would like to describe the co-molding stage in fabrication for all of us, please feel free to drop comments. As far as I believe, it is a simultaneous molding process where both parent parts are placed in the mold and heat treated, thus expanding and forming the carbon fiber within the second material.
Finally, take a visit to the ZIPP production facility in Speedway. I have no doubt it is one of the fancier carbon composite fabrication spots in US, where bicycles, military and race car tech intermix. VIDEO COURTESY to DVXBRIAN.
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Ron,
ReplyDeleteYou're pretty close with your definition of co-molding.
Comolding is when you have a parent part (such as a rim, insert, or cured composites) that gets molded with uncured composite (carbon/epoxy).
HED's way of doing it is basically taking 2 "parent" materials that are already cured and then applying a high strength adhesive to join them together.
From a bond strength standpoint, HED's way is typically stronger because the adhesive epoxy used is typically stronger than the epoxy used while co-curing(co-molding).
Co-molding has advantages in that you can cure more complex shapes than with the secondary bonding.
All in all, if done appropriately, both methods work.