My chain keeps hopping off the upper gear of my Suntour Cyclone M-II derailleur (circa 1983). The chain ends up riding on the edge of the derailleur nearest to the wheel. It looks to me like the gear is just plain worn out, which is reasonable after 26 years:


At the LBS, they say they can't get parts and I should go scrounging for an old one to steal parts from, or replace the whole derailleur with something comparable. Not that it really matters, but it's a Trek 730 that I bought new and I'd sort of like to keep the original components going, such as they are, for sentimental reasons more than anything else. I'm open to suggestions to the contrary.

Any ideas?

Thanks,
Dan
p.s. Related pictures here.

What's worn out, just the pulley wheels? Those shouldn't be a big deal to replace, I bet you don't even have to have Suntours. Correct me if I'm wrong, everyone, but I'm thinking the pulley wheels off almost any derailleur will work.

Don't the teeth on that wheel look pretty much worn out? I'm guessing that's the problem, but I'm as far from being a bike mechanic as I am from being a Ferrari mechanic, so feel free to enlighten me. The only other observation I can offer is that the pulley wheels don't turn as easily as I imagined they would. But then, the whole thing is pretty grungy so if I disassemble, clean, lube, and reassemble, that might go away. I'd rather put in a new pulley wheel while I'm at it. For what it's worth, the mechanic at the LBS seemed to think I'd need the same Suntour part for it to fit.
Thanks,
Dan

Well, a week or two ago I was adjusting the derailleur on my 1984 Counterpoint Opus II, which is a first generation Shimano Exage, the one with a deer head on it, and I noticed the pulleys are Suntour sealed bearing ones, installed who-knows-when as an upgrade. As long as the bolt threads into the cage properly, I'm pretty sure you won't have a problem with different pulley wheels. You can buy snazzy aftermarket ones, or scrounge something. Try, anyway; if it doesn't work, you have other options.

You definitely need new pulleys on that derailleur. Regular (non-sealed bearing) Shimano pulleys will NOT fit since their bushings use a smaller diameter bolt. SunTour used the same size pulleys in all of their derailleurs, so if you can get hold of a cheap all-steel Suntour derailleur, you can pull out the pulleys for your Cyclone.

+1 Just pick up a decent Suntour RD on ebay or wherever.

I have a Suntour GPX RD that I could steal the pulleys out of if they will work for you. Just pay the shipping and they are yours.

Hi ZeRinger,
That would be a great favor to me. Can I paypal you some amount to cover shipping? Please contact me directly if you can: dan mills at cruzio dot com

Thanks,
Dan

I just sent you an email. Reply with your mailing address and I'll get them out to you. On second thought, don't worry about the shipping costs... it is on me.

Darin

That is a good derailleur and worth seeing if you can bring it back to life again.

jim

You should have no trouble finding decent used pulleys that will work in that derailleur, irrespective of brand, but subject to the leecycle's caveat regarding bolt hole size. When the chain skipped on low gear during a 12% climb, I replaced the chain and both pulleys of my Campagnolo 980, which now has Japanese pulleys.

I talked to somebody running these and he was extremely happy with how crisp his bike shift now. They come with shims to make it a universal fit. I plan to pick up a set of my 1989 R600's 105 RD today.

https://www.performancebike.com/bikes..._400002_400185

Just curious if you still need these? I never heard back from you after emailing you.


Darin

I ran across these pulleys at loose screws if someone needs some.

https://www.loosescrews.com/index.cgi...d=420496814755

Hi Darin,
I just looked and found my reply to you (from 5/30) in my email outbox, so I don't know why it didn't go through.

In any case, I now think you should save yourself the trouble of sending me the pulleys you offered, because I've since come up with another solution. I just found a good deal on an entire replacement derailleur of the same type. The old one was a little bit bent, and somewhat worn from the chain jumping the old pulley. Not to mention the fact that I haven't yet figured out how to change out that upper pulley anyway! Perhaps once I get the replacement mounted I'll offer up the old one gratis to anyone who has the skills and wants to put it to rights.

Thanks again for your generous offer, but no need to follow through on it now.

Dan