Monday, July 29, 2013

Carbon rims and radial trueness

Lateral trueness is easy; radial trueness is hard. I'm always looking for better tools, and this morning I was researching Morningstar tools. They offer a dial-based truing gauge that will fit to a Park TS-2. Slowtwitch was the first review that popped up. Buried within an article on wheel building is a point about the difference between carbon and aluminum rims:

This is also the point where carbon and aluminum wheels differ. Carbon rims are much stiffer than aluminum. Put simply, the amount that you can radially manipulate a carbon rim is MUCH less than aluminum. As such, when adjusting radial trueness, you need to adjust many more spokes. Think of it as shifting the entire rim up or down – rather than bending a part of that rim to be more straight. Instead of adjusting 4 spokes, I might adjust 8 or 10. This also brings up the point that carbon wheels rely much more on roundness of the rim itself for a straight wheel; an imperfect rim cannot be manipulated very much (unlike aluminum). 

This is why cheap carbon rims are a really bad idea. There are plenty of other reasons why cheap carbon is a bad idea--labor conditions in those Chinese factories, for starters. Next up would be a total lack of warranty coverage for manufacturing defects.

Want a legit rim and customer service? See Brandon at the Bike Hub Store. Always great service and they're the only consumer source of Gigantex rims that I've found:
http://www.bikehubstore.com/category-s/124.htm