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Zenon2008

Hello

I'm enjoying my Tour de France ca 1976, but feel I need at least one lighter gear for the hills, so I am looking into bying a 7-speed freewheel.

I have this derailer

http://farm3.static.flickr.com/2183/2438563214_db4f3c2830_b.jpg

Does anyone know the model and the maximum cog it can handle? Can it handle a 7 speed freewheel? Is there a different derailer that will fit the dropout that might be better suited for this purpose? Any comments would be appreciated..

John

sandranian · Site Admin

Chas. will know the answer to that. I would bet his life on it. Wink

Zenon2008

Ok, thanks, hopefully Chas. will drop by...

A little update. I'm thinking that buying a Suntour Cyclone/Superbe rear derailluer might be an alternative, and that I either buy a 7-speed freewheel or respoke the rim with a freehub to fit a 7-speed cassette. With the Suntour I assume that I will have to tap threads and file a notch in the hanger.

Gtane

John,

You could well have a version of the Prestige model, but I'm not that well up on Simplex. Some info. here;

http://tinyurl.com/2fxlcao

It might be tricky going to a 7 speed freewheel without work to increase the space between the rear dropouts. 7 speeds were used by the Pros in the '70s but I'm not sure they hit the mainstream until the '80s.

I've used various 5 speed and double front combinations without issue. For wider 5 speed combinations (32 teeth, even a 34 at one point) I have always found the the Suntour GT and VX rears to be excellent and totally reliable.

Tim

Zenon2008

Thanks, if you are right about the Simplex I have, it takes a 30 teeth cog, which should be enough for me, and I could simply look for a different freewheel. The present freewheel is 6-speed btw. According to Sheldon, it isn't that difficult to respace the frame though..

verktyg

Suntour made what they called their "narrow" series freewheels. A 6 speed narrow would work on most 120mm wide 5 speed hubs.

In the mid 80s Shimano set the industry standards for rear hub widths when the brought out their SIS indexing system:

5 speed freewheel/cassette hubs - 120mm wide
6 & 7 speed freewheel/cassette hubs - 126mm wide
7+ speed freewheel/cassette hubs - 130mm wide

Before that the the "standards" ranged from 118mm to 128mm wide! Shocked

Soon other freewheel manufactures started producing "narrow" freewheels and later made cassettes too.

Here's some "standard" widths but YMMV!

Standard 5 speed freewheels were 25mm wide
Standard 6 speed freewheels were 31mm wide
Narrow 6 speed freewheels were 27mm wide
Narrow 7 speed freewheels were 32mm wide
Narrow 8 speed freewheels were 36.5mm wide

You need a hub at least 126mm wide for standard 6 speed and narrow 7 speed gearing.

Then... you need to have enough room between the freewheel and the seat stay for the chain to easily shift on and off of the smallest cog without hanging up.

You may have to file the inside of the bottom of the seat stay (and sometimes the chainstay). to get enough clearance.

Your Simplex rear derailleurs "should" be able to handle at least a 28T rear cog and probably a 30T cog. You may have to add a chain link or two and play around with the wheel position front to rear in the dropout. Figure on not using the large-large and small-small gear combos. Get one of the newer flexible chains like an SRAM PC850.

The standard model Suntour Cyclone/Superbe rear derailleurs were made for racing and had a 26T maximum cog size. The long arm Suntour derailleurs could handle more teeth but maybe at a loss of performance on the close together cogs.