Hi guys -
Foam is way lighter than any ABS/HDPE plastic. A simple way to make sure the foam doesn't stick is just to use some poly (PE) sheet and you can even use cardboard to support the foam.
We are building a "wing covering" much like the model airplane guys do. There is a thread on here where a guy used wing covering material - only. No foam core. I don't know how durable that would be tho. Because this is a bike, there needs to be some sort of baseline durability. The foam method does this, but with just a vinyl covering you can make a finger dent in it pretty easy. ie Zipp et al could not build like this because customers would freak out. ("I have a dent in my $2500 wheel and xxxx won't warranty it")
Vinyl covering - On the raised side (non-gear side) I had to cut the vinyl once along the line of the spokes. Do this from the valve access hole to the center of the wheel. (I didn't and it looks a bit goofy). The vinyl wrap doesn't like to stick to itself - so I cut the seam flush and used epoxy - several applications to seal the butted seam. I also used the 5 min epoxy to seal the valve access hole exposed foam edges. I mixed in carbon powder for that awesome grey look.
Also - You might want to hit the whole foam surface with a paint/primer - even water based, prep the surface so that the vinyl can stick a bit better. The vinyl did not stick that well to the foam but after a couple of weeks of smoothing it out (hot sun etc.) I have no more lifting or bubbling.
Bottom line - I took a cheap wheel that I was just going to pitch in metal recycle and built an awesome sounding & looking disc that I ride all day long. So yeah it's cool.
To do again??? I would start with a better quality, lighter, wider alu wheel. I might try using balsa wood & urethane glue as the filler vs the foam. But if that lost the sound, I'd be bummed out. And finally for the covering I think I would go true carbon fiber, thin layer of epoxy, then a clear coat, two part. Takes more time but would be more robust and easier to get a nicer, smooth finished product. I would like to build another disc. I think this is a great approach, HED/Zipp hybrid of sorts - cool sound, clincher style, and if you can score a great used/new wheel ($200) the total cost would be no more than $300, a few beers and the wife and kids wondering where u are hiding.
Note
1. ABS is a bit nasty (fumes, melts when cut, brittle etc.) I like HDPE from Quadrant, excellent stuff, but it is the PE (polyethelene) family. Which means it's slippery and breaks down with a lot of flexing.
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