I buy Tacx pulleys they're nylon.. and quieter I have them on
chain tensioners.. & friction shifted derailleurs
BITD pulleys were just round , because chain side plates were bigger than chain rollers..
now for faster shifting the chain's side plates are same width as the rollers , so your pulleys need teeth
at least the top one.
....
Last edited by fietsbob; 06-25-19 at 08:14 AM.