You hear the chain passing thru metal tooth pulleys .. Tacx Nylon Sealed bearing pulleys are quieter
even than other plastics that are harder.

Tacx, Thru the usual distribution channels, will also sell you ones with more expensive ceramic bearing
in their pulleys too .

I got a set of pulleys from Carmichael about 20 years ago .. titanium rather than aluminum.. (my Touring Bike , no cracked plastic Pulleys , again,Thank You)



as usual you have to decide for your self if It's "worth it".




???