Accushift x SIS

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???

Edit: wut?

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.