Classic & Vintage - Suntour Cyclone Mk-II rear derailluer: chain wrap capacity?

I'll be putting together my '83 Centurion Pro Tour before long, and I want to use a Suntour Cyclone
Mk-II rear derailleur that was stock on the bike. I've switched out the chainrings to my liking, here's what the gearing will look like: six speed freewheel, 13 x 32. Triple crankset: 48 x 36 x 24. That means the rear derailleur will need at least a 43t chain wrap capacity. Anyone know for sure if the Suntour Cyclone Mk-II can handle this?

Is that a long-caged derailleur you have? If not, you may have issues with your freewheel.

Yes, it's a long cage derailleur (it's a touring derailleur after all), but the cage isn't quite as long as something like a true mtb rear derailleur. I'm not really concerned with the max. large cog capacity, I'm fairly certain it will work with a 32t. But with the 24t difference between my big and small chainring combined with the wide ratio freewheel, I'm increasing the chain wrap requirement a little over what the stock gearing would have been, and that's what concerns me. I'll know for sure once I get the bike built up, of course, but I was hoping someone might know off hand what the Cyclone Mk-II is rated for-

Is that a long-caged derailleur you have? If not, you may have issues with your freewheel.

+1
The short cage Cyclone MkII would work great on a 13-21, 13-24, etc freewheel, but I believe you'll need the long cage for the freewheel you are using.

+1
The short cage Cyclone MkII would work great on a 13-21, 13-24, etc freewheel, but I believe you'll need the long cage for the freewheel you are using.

Maybe there were two versions of the Cyclone Mk-II (long cage and short cage)? This bike, when I bought it, had the 13 x 32 six speed Suntour freewheel and Mk-II rear derailleur on it, and in looking at the derailleur it's definitely what I'd consider "long cage." The bike wasn't rideable when I bought it, and I ended up stripping it of its parts without ever riding it, so I can't say for sure the derailleur will work with the 32t large cog, but my guess is that it probably will. But it's just a guess; hell, now I've got two things to worry about- :D

I believe the long cage versions were named GT, as in Cyclone MK-II GT. I have a GT on my old Puch and it appears to be the same cage length as the 7 GT that came with the bike originally. The normal Cyclone had a capacity of 28T, max sprocket 26T. I can't find the info on the GT version, but I think it may be 34T capacity. My Puch originally came with a 52-40 front and a 14-32 rear, and shifted fine. I really like the Cyclone MKII. It is nice looking (I like the way the cable goes into the main body) and very light. The open cage design is really handy when you take the wheel off, I wish the Shimano RD on my Giant was made that way. I don't ride it hard, so can't comment on the longevity though.

Bad news: I believe Cyclone MK II GT RD capacity is 34 T, largest cog is 32 T. You would be pushing it with your planned conversion. I have read that you could push the MII capacity to 36 T if you don't cross-chain.

Good news: Deore LX M570 RD long cage is on closeout at about $31 delivered (Cambriabike.com, icycles.com, ebay and so forth). Its got the capacity/specs you need, although the cage design is nowhere near as visually elegant as the MII...which IMHO is an absolute marvel of form and function.

I'm running a Deore M570 RD and Cyclone MII FD (touring version, stated capacity 18 T) on a 50/46/32 front 14/32 rear. Works like a champ. The MII GT RD sits in the closet, on hiatus until its time to return its donor bike to original form.

Thanks for the info, guys. It does indeed sound like I'm beyond the derailleur's capacity in terms of chain wrap. I'll probably opt for putting an old mtb RD on the bike, I've got a few of those lyiing around that should have the capacity I need. Kind of depressing, though, because I agree the derailleur is very nice looking. I've got another Suntour RD off of an '84 le tour, exactly the same shape, size, etc. as the Cyclone Mk-II, but when held side by side it's clear the Mk-II weighs about half as much. Quality stuff. I do wonder what the original gearing was on the bike. I'm pretty sure the chainrings were 50-42-28, but I'm not sure about the freewheel. I assume the 13 x 32 six speed wasn't stock, since the full name of the bike is the Pro Tour 15-

My 83 model Pro Tour 15 came with a 13-28 40 spoke 27" rear wheel. The Cyclone II worked well with this set up. I have since replaced the rear derailer with an LX and went to an 8 spd rear wheel 36 spoke in 700c with bar end shifters for touring. By the way, what color is your Pro Tour 15? Mine is two tone blue.

My 83 model Pro Tour 15 came with a 13-28 40 spoke 27" rear wheel. The Cyclone II worked well with this set up. I have since replaced the rear derailer with an LX and went to an 8 spd rear wheel 36 spoke in 700c with bar end shifters for touring. By the way, what color is your Pro Tour 15? Mine is two tone blue.

Yep, mine is two-tone blue also, with full chrome beneath the paint, exposed chrome on the driveside chainstay, at the top of the seatstays, the top of the fork crown and at the front and rear dropouts. Beautiful bikes! Thanks for that info regarding the gearing, I guess then the bike came stock with
50 x 42 x 28 up front with a 13 x 28 five speed freewheel, with the Suntour Cyclone Mk-II GT rear derailleur, Suntour Mountech front derailluer and Suntour Symmetric downtube shifters. Is that the setup your bike had?

Yes, It came with 50/42/28 chainrings. I used the same crank but changed the rings to 46/36/24 and it works fine. The front derailer was changed in 85 to an Exage and it still works fine. Mine also has internal wiring for a light but I don't have one on it at this time. It is a fun bike to ride.

Don't know exactly how this transfers, but the original Cyclone (short cage) was offered on the 1977 Raleigh Super Course - which had a 40 - 52 chainring and a 14 - 28 freewheel. Never had any problems with it.

After looking closely at the derailleur, I found the letters GT stamped on the cage. Suntour probably stated the "official" chain wrap capacity as 34t for the GT version of the Cyclone Mk-II as Boatdesigner and mrmw said, but it apparently would take up as much as 37t in chain slack, since that's what the stock gearing on the bike would have required (50-28 + 28-13). Since I'm way beyond that with the gearing I'm wanting to run, I'll either have to re-think my gearing or install a longer cage derailleur. I was in the basement a little while ago and found an early to mid '90's Shimano LX RD that would work fine, but still.........that Cyclone Mk-II GT is just begging to go back on the bike. The jury's still out. :D Thanks everyone for the replies-

I believe a Suntour XC 9000 or GPX long-cage would be adaquate subsitutes that both look the part and can handle the additional chain wrap.

-Kurt

I believe a Suntour XC 9000 or GPX long-cage would be adaquate subsitutes that both look the part and can handle the additional chain wrap.

-Kurt

Thanks for the info-

Good info guys! At least I know my short cage M-II can handle what I want to use it on! Cool!,,,,BD

Original Cyclone short cages came on 78 Continentals too, so they work with that size freewheel also. Not sure
what it was? Maybe 14/28?

Well-biked, did you ever end up using that mk-II the way you wanted to? I am planning on using it with chainrings 48-38-24 and a 13-32 freewheel.

I dont want to hijack this thread but as the original question was well-fielded i will pose a Cyclone question.
I have a cyclone mk-II that is missing its cable retention bolt.
Well, the bolt is there but the 5mm allen nut that goes on the outside is missing, how would i source this part?
http://i42.tinypic.com/53wk92.jpg

If you have the front derailleur use the nut from it, and find another nut that is not as critical for the front. I did that on mine, and it worked perfectly.,,,,BD

I dont want to hijack this thread but as the original question was well-fielded i will pose a Cyclone question.
I have a cyclone mk-II that is missing its cable retention bolt.
Well, the bolt is there but the 5mm allen nut that goes on the outside is missing, how would i source this part?
http://i42.tinypic.com/53wk92.jpg

Would a brake caliper cable fixing nut work? I have a bunch of DC ones. PM if you want one