Originally Posted by
Jeff Wills
Uh... maybe. I've used non-ramped & pinned chainrings on a couple bikes and the shifting quality has been acceptable. It's not always effortless- I've had to force a 24-to-39 shift sometimes- but it's always worked. This is on recumbents with MTB Rapidfire shifters and FD-R443 front derailleurs.
I think rmfnla does make a good point. A flat middle ring will shift adequately but not nearly as quickly or effortlessly as the newer enhanced chainrings. After all, years ago no one had ramped and pinned rings and we did manage to shift them but the newer designs are significantly better.
I have an older bike that originally came with an SR triple crank and, of course, completely flat chainrings and friction shifting. It did shift the way cranks used to shift, that is ok but not well under load. After a while I swapped the SR for an 8-speed era 105 triple crank using exactly the same gearing, same front derailleur and same friction shifter, and the shift quality improved very noticably.