I want to install a Shimano derailleur on a bike that has 7 speed Suntour barcons. From what I’ve read, opinions on the matter seem to vary quite a bit, ranging from “the actuation ratios are practically identical” to “it won’t work at all”. Does anyone have any experience with this setup?
I don’t have experience with that exact setup, but I avoid mixing S & S indexing, because of frustrating experiences. I’m not sure if the problem lies in the derailleur or the freewheel choice, though. Generally, I parts bin it until I have a matching set of one or the other.
Look at this:
Spacing seems the same so should work.
Now, way back when I was a beer drinking herb smoking wrench, I remember Shimanos upper rear derailleur jockey wheel had lateral play that Suntour could not copy due to strong patent mojo.
Me thinks it will work better???
Acushift spacing is all fucked up.
I know where you can get a nos groupo…
upper rear derailleur jockey = Tension/Guide pulley. I would have to believe the diff in High/Low in cassette spacing is in the suntour derailleur as it moves, so a matching shimano cassette should do the trick. If I’m a liar and it’s in the shifter, dismantle the cassette and throw the right size spacers in there. From what I read though, I think Suntour used a 1.5:1* (weird, no? I’d expect 1:1.5 if anything) actuation ratio so who knows.
*Uniform actuation ratio would indicate the weird cassette spacing was in the derailleur ATMO.