Orient Express - Cheap Chinese Rims / Wheels / Forks / Frames / Cranks / Etc

rim braking tracks, grooved graphene vs high TG

I don't know what they mean by high TG. High TG in the composites world means a higher temperature resin, i.e. the resin softens at a higher temperature. They use a lot of meaningless TLAs though (TCT, GGB, FTA, ART), so don't assume high TG in their context actually means that unless they've spelled it out somewhere.

Let's also be clear, actual graphene doesn't exist properly in the composites world yet. It's a marketing term. What they're probably referring to is a resin heavily loaded with graphene-like graphite particles, which makes it more abrasive and therefore a better braking surface than pure epoxy.

U vs V-shaped rims. I'm assuming U is better

I think it's pretty accepted these days that U shape is more aero than V shape.