Off topic.
AVID parts and bearings are available from P-DubRacing. (
www.p-dubracing.co.uk)
On topic
From my understanding the lower ball-stud on the hub and u-brace is supposed to generate more traction on the rear. This would be when used on the B4.1.
I've yet to try them, but it looks like running these on the 0.5 / 1.0 alu hubs it will allow you on the C4.1 to run the hubs the right way around, so adding rear toe-in, useful for low traction situations. It will also allow you to run the hubs reversed (left on right - right on left) to reduce the rear toe-in.
MiCk B. :-)