Originally Posted by
pccp
Ya I think you're right, it looks like the T version from
this picture. 28t Total capacity so I would need to change the rear derailleur. Because it's friction shifting couldn't I just get cheap medium cage modern RD with the right total capacity?
You might run into another problem: a Simplex RD hanger that's integral to the frame.
The Simplex Mounts section of this article (I believe it's by regular BF commenter @
jonwvara ) explains the potential issues.
Most modern RDs expect to find a Campagnolo-style dropout (or the newer "direct attach" type). If you have a Simplex-only hanger, that will be an issue.
I also have read somewhere that at some point Simplex started making rear dropouts with integral hangers that included the Campagnolo-style "tang". If that is correct and your frame has one of those (or has a Campagnolo-style dropout), then the hanger issue shouldn't crop up.