Bicycle Mechanics - 12-28 7-speed threaded freewheel source
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05-02-10, 01:25 PM
I have an old (1997) Vision R-85 recumbent tandem that is my wife's and my pride and joy. We ride it about 2000 miles a year. Recently I replaced the chains, which had stretched considerably, and not surprisingly I realized the freewheel cogs are also worn and in need of replacement. The bike has beautiful and rugged Phil Wood hubs with a 7-speed threaded freewheel, currently a Sachs 12-28, which is no longer made. The only 12-tooth 7-speed replacement I can find is a 12-19 racing model, not something that would ever be used on a recumbent tandem. I can find 13-28 replacements, but I really don't want to give up the 12-tooth cog, which is extremely useful when powered by two riders with a tailwind or on descents.
Is there a source for a 12-28 7-speed threaded freewheel anywhere today?
05-02-10, 02:38 PM
Those Sachs freewheels were sweet. Someone somewhere may have replacement cogs for it, but I haven't seen any in years.
How about picking up a more easily available 13-32 freewheel instead (like this (http://www.rivbike.com/products/show/ird-freewheels/13-091)), then changing your big chainring to something 4 teeth bigger? You'd maintain the gear ratio you like that way. Only concern is that your front derailleur's tooth capacity may be exceeded, requiring a bigger small (and ideally the mid) chainring too.
05-02-10, 04:34 PM
Yes, I know about the 13-28 replacements, but I really don't want to give up the 12-tooth cog. The loss of the "road gear" is a major issue for a tandem. As it is, we can sometimes out-spin the 54-12 with a good tailwind. And you have exactly identified the problem with a larger front chainring (say, 56 teeth): it would exceed the capacity of the front derailleur, basically requiring replacement of the entire rear drive train.
I keep thinking someone has a threaded 12-28 freewheel somewhere, or perhaps replacement Sachs cogs (only three of them are well-worn). By the way, has someone come up with a universal search engine for craigslist and kijiji in all locations?
05-02-10, 05:02 PM
115 RPM equates to 38mph with a 54-13! I am impressed!\
I don't know if this will work with your setup,but it's probably one of the best made. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310207289173
05-02-10, 05:19 PM
There's this too:
Big cog is only 26, but Yellow Jersey (http://www.yellowjersey.org/stfw.html) may have some to create a wider range.
Loose Screws has the Winner Ultra on sale right now too:
05-02-10, 05:34 PM
The 12's aren't easy to find, but they do come up on ebay, and cheaper than the $125 dreamer. That one's been up a while. Just keep looking there.
05-02-10, 08:17 PM
I also found the Suntour 12-30 at Loose Screws. It's not cheap, either, but considerably less than the outrageous price for the 12-28 on eBay. I'll have to seen if my dérailleurs can handle a 28-30 granny gear.
This leads to another question. I've got an old Suntour Winner body and various spacers in my parts bin. Is there still a source for Suntour Winner cogs? Back in the day (25 years ago, I admit) every good shop had a board with Suntour cogs. I could (and did) custom-build any reasonable freewheel configuration I wanted.
I know; I'm sounding like the old fart I am.
Are you positive your FD can't handle a 56t cog? What's your chainrings now? Is this based on actual trial, or by manufacturer spec. ? If it's spec, then it doesn't mean much, FD's are always under-rated. If you could use the 56t you'll have a supply of good 13-28 IRD FW's for a long time.
Otherwise ....You don't have to buy a 12-28 7sp. Sachs freewheel, just buy any 12-19,12-21,12-24 7/8sp. or whatever in a Sachs and take off the 12t cog to use. These are on ebay every week for around $20. The two small cogs are the same for 7 and 8speeds. IY and LY .
05-03-10, 02:09 PM
This leads to another question. I've got an old Suntour Winner body and various spacers in my parts bin. Is there still a source for Suntour Winner cogs? Back in the day (25 years ago, I admit) every good shop had a board with Suntour cogs. I could (and did) custom-build any reasonable freewheel configuration I wanted.I have a full Suntour cog-board. Send me a PM with the cogs you need.
Sachs made them for some years before the 130mm rear spacing took over. Spidel/Maillard also had seven speed freewheels if you are into the French classic stuff (I run them on my 1985 Vitus Plus Carbone bike, but they are harder to find than the Sachs as they did not make them for too long before Spidel died out. Please note that these 7 speed FWs do work best with narrow chains though.
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