I have a beautiful cyclone derailleur. I think it is 70's vintage. What is the the teeth capacity? How do I tell if it is the original or MK2...I think I would like to use it since the weight and condition is so great.

I think MKII states MKII on the body. The capacity should be about 28teeth unless it is a long cage, but then it would say cyclone GT on it.

Look at the back of the parallelogram cage and you should see an inscription reading "MAEDA INDUSTRIES, LTD ... JAPAN" - or some such. There should also be two small mysterious upper case letters - which would be the date code for year and month. Let us know if you find this.

Photos would be useful for identifying the exact model ...

If it's first gen. (not MKII) and not a GT, its capacity will be less than that - officially, those Cyclones were rated for 13-24. They were intended as racing derailleurs. The capacity for the first gen. Superbe introduced in 1977 is even less.

Cyclone MkII is early '80s. On the first generation Cyclone and the Sprint, I've run a 26t largest rear cog with no problems and I think the MKII will have no problems with a 26t either.

The first generation Cyclone was original equipment on the 1977/78 Raleigh Super Course, which came with a 14-28 freewheel. I didn't have problems with it when I had a new Super Course, and I don't have a problem with it on the Super Course I have today.

Does it look like this one?


Unfortuntely the data on VeloBase on this model is incomplete in respects to chain wrap. 28T sounds like a reasonable guess for the chain wrap on these though.

List of all suntour rear derailleurs on velobase can be seen here: https://velobase.com/SearchVisual_Lis...l_Category=108

My info that the first gen. Cyclone was rated for 13-24 is from a Suntour chart reproduced in Frank Berto's "Dancing Chain." Don't doubt that it can handle more, but wanted to be clear where my data came from.

Here is some data on the Suntours from 1976 showing chainwrap and largest cog sizes for the "Cyclone", "Cyclone-GT", and the various "V" derailleur models"

For a larger image which you can actually read clearly... CLICK HERE

Looks like ya'lls information is better than my rough guess. Which is one of many reasons I started velobase to begin with so a lot of this information might be able to get collected in one place online for reference. I'll get my information updated.

Did I read that correctly...34 tooth max for the cyclone GT ?

This is the chart I referred to which is reproduced in Berto's book.

I was talking to a guy on the phone last night who was trying to ID some derailleur and he said "I'll just look it up on VeloBase" And I said "Hey the guy that created that is a regular on bikeforums C&V!"...
That is really cool. Keep up the good work Jon!

The 53-40 / 13-24 capacity, i.e., 24 teeth maximum cog and also 24 teeth wrapup, sounds about right for the Cyclone. I happily ran mine on a 48-45-34 / 13-15-17-19-21-23 half-step-plus-granny, which fits this paradigm, and I had just enough windup capacity to let me crosschain both ways, not that I ever used those ratios.

36 with hanger! I don't think I've ever seen a 36T large cog, but I haven't been around all that long.