It's not for traction, it's for cheap (rubber on aluminum has plenty of traction already). Why polish the rollers when all they see is rubber?
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter