Originally Posted by
Kontact
Depends on the disc. The oldest ones had a sheet metal part that went under the freewheel. But most of them for the last 30 years just attach to the spokes.
It's been 40 years since I pulled a new bike out of a box. Never bought one with a disc. (Last bike I purchased of that price range was before they existed.) Now that you have reminded me, I do recall seeing the clip-on ones at the non-profit shop I've volunteered at.
Ben