Post
by Nick Krest » Mon Apr 04, 2005 5:55 pm
The problem with trying to check the duros on those old wheels is that the urethane formulas were pretty unstable. PowerFlex wheels were advertised as 82a, and the RRs were definitely in that ballpark. You can't ever be 100% sure, because even now, carefully mixed urethane batches can vary by +/- 3 points on the Rockwell A scale (confirmed by John Tiedemann at Creative and Tim Dawe at Electric). So let's say RRs were somewhere in the 80-85 range, John?
Another thing to take into consideration was that the Krypto urethane starting in November of '77 had a super-high resilience, which was something that had never been done before. You could run a higher duro (78a red, 86a blue, 91a green) and still maintain grip, as a higher-resilience wheel springs back from deformation more quickly. I agree that you could pull an uncored red Krypto right off the bearings while still mounted, because I've done it. Early loose ball wheels (Cadillac, Roller Sports, Metaflex) didn't pop their races too often; I wonder what duro they were (knowing full well, of course, that Metaflex were quite a bit harder than the more popular Cads and RS).
Now you're going to make me go buy a new tool - a durometer.
Sorry about that double-stepped lip not making it into production. Jay Shuirman was indeed a mad scientist, and had an intuitive feel for products that worked. SCS wasn't the same without him.