RI_Swamp_Yankee

I've got a Suntour GT derailleur with friction shifters, and I swapped out the old 5-cog freewheel for a new IRD 13-32 5-speed freewheel. I've got the derailleur mostly dialed in, but I can't go from the 32-tooth cog to the next cog over... it skips straight to the one after that, and when downshifting, I have to be real careful, or the chain will go straight to the "mega range" gear, skipping over the intermediate-low gear. The other gearshifts are normal and smooth, and I am, of course, using the small ring up front (38t, I think). I only use the big ring when I hit the 13t cog and need mo' go.

Is this a tensioner thing, or a B-screw thing, or even a L-stop thing? Something else? It's pretty weird.

JohnDThompson 

What size was the original freewheel? Sutherland's states that the GT has a maximum capacity of 30 teeth.

RI_Swamp_Yankee

Both SunTour and the guy who runs Disraeli Gears says it should handle up to a 34t cog without issue. Getting the chain onto the 32t isn't a problem - it doesn't even complain or "chatter," there's plenty of room left between the cog and the derailleur wheel, enough where I had to bring it in with the B-screw. The only problem is in getting the chain to the cog next door. I'm half convinced it might be a shifter issue.

Retro Grouch 

I suspect you have an issue with the vertical alignment of your derailleur. When viewed from the back, your derailleur arm should point straight down. If it points inward, it'll act the way you have described. If that's the case, you can probably bend it back straight with your hand.

invisiblehand

I assume that it could be the derailer hanger instead of the derailer that is bent. Wouldn't one want to test that out first before bending the derailer?

Retro Grouch 

I was careful to say what I said. Some of those old Suntour derailleurs had a hanger that bolts onto the dropout and some bolted onto a hanger that was part of the frame.

bikeman715

yes you may be right about a shifting problem, first have the hanger check and if that does work then replace the cable and housing.this should solve your problem.

John E

You might also experiment with the fore-aft positioning of your rear wheel and the mounting angle of your derailleur body. I had very good luck with a SunTour V-GT, first with the original 14-18-22-27-34 SunTour freewheel, and then on my wife's bike, with my custom 16-18-21-24-32 SunTour.