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SunTour freewheel replacement

Old 06-30-20, 10:10 AM
  #1  
ndrose
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SunTour freewheel replacement

The Great Bicycle Scare of 2020 is hampering my quests for a new bike and for a new freewheel for the old bike. The cupboard is pretty bare on both counts in shops around here. Iíll have to wait on the new bike, but I may be able to get the freewheel online. However, I donít know enough to be sure whether Iím getting the right thing.

The old one is a SunTour accushift plus 7-speed 13-28. Confusingly, one bike shop guy told me these are still made, but I donít think thatís correct. (Is it? Maybe he was thinking of Sunrace?)

The Sheldon Brown spacing cribsheet seems to indicate that at least some Shimanos should work without also replacing the derailleur and shifters, but Iím not sure how to tell whether a particular freewheel will work.

Does anyone know whether this would be right?

https://www.harriscyclery.net/produc...ewheel-780.htm

Would there be any problem going from 13 to 14 teeth on the smallest cog?

There is also this one:

https://www.harriscyclery.net/produc...wheel-6331.htm

Any help much appreciated.
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Old 06-30-20, 10:18 AM
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Is this bike setup with indexed shifting? If not, any old 7-speed freewheel will work as long as the biggest cog isn't too big. If you have decent calipers you should be able to measure the spacing of your current freewheel and compare to Shimano (all should have the same spacing.)

No problem going from 13 to 14T on the smallest cog.

The old SunTour is long gone and I'd be very surprised if anything remotely close to what they used to make is being produced today.
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Old 06-30-20, 10:22 AM
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ndrose
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It is indexed.
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Old 06-30-20, 01:52 PM
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Might want to ask in C&V where more people have actually done this stuff.
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Old 06-30-20, 01:55 PM
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Sun tour seems to just be a brand name of a suspension fork supplier currently .,

Freewhweel you may have to buy who is making them now such as Sun Race, or Shimano or similar..
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Old 06-30-20, 02:08 PM
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Be aware that some Suntour Accushift freewheels had cogs of different spacing between cogs. Your best bet is to buy from Ebay or somewhere else online a Suntour freewheel of the same model # as the one you have. Or change the freewheel and the shifters.

Cheers
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Old 06-30-20, 05:17 PM
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Your first step is to make sure it is a 7 speed freewheel and not cassette. I'm assuming it is a freewheel.

I am also assuming you have Suntour Accushift Plus downtube shifters or Suntour Accushift Plus thumb or X-Press shifters.

Here is some interesting info Suntour freewheels and cassettes...
Archival Reviews of Suntour Freewheels/Cassettes - the Buyer's Guide, 2015

And Sheldon Brown's Cribsheet...
https://www.sheldonbrown.com/cribsheet-spacing.html

If you are able to unthread the first cog and separate the cogs from the freewheel body, the older ones allowed for this to swap out cogs, you can measure the spacers to see if the are all 3.15. If they are, they you should be able to use any Shimano/Sunrace 7 speed freewheel and it should index.

If they are not, here is an option...
https://www.ebay.com/itm/SUNTOUR-FRE...sAAOSwgbte1Ahh
I would contact the seller for a P/N off the box.

You can always change from index to friction and use the Shimano/Sunrace freewheel. Or you can buy Shimano 7 speed index shifters form $20 to $80 (eBay).

And there are probably people on C&V subforum that have better info.

John
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Old 06-30-20, 05:22 PM
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Or PM Pastor Bob, and ask him. Smiles, MH
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Old 06-30-20, 09:36 PM
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The ST indexed systems of the 1990s was never intended to interchange with Shimano's stuff. As mentioned the cog to cog spacing was different and while a shift or two might be good after a few more the differences will add up to chain rub and/or hunting between cogs. The best long term solution is to either find old but still useable ST stuff (EBay??) or move on to stuff that is currently supported by a few manufactures. This means shifters, cog sets and ders at the least. Andy
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Old 06-30-20, 10:21 PM
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...as already stated above, Suntour Accushift was unique. And not always in a good way.

If you can live without indexing, you can probably get it up and running cheaply by just buying a 7 speed Sunrace freewheel off Amazon. Then either set your shifters to friction (if that is an option...I've not worked on your particular version) or replacing your shifters with some friction ones, also made by a bunch of companies like Sunrace, and also sold on Amazon, or wherever you buy used parts.

I have no idea if you have DT shifters, barends, on the bar thumbies, or something else. But these are all available used. They are left over from the stone age, before indexing, when life was good and I was young.
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Old 07-01-20, 07:42 AM
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Thanks for the many replies. The division of opinion mirrors the uncertainty I began with, whether the spacing will be the same with a new freewheel and allow the shifters to work.

The Sheldon Brown cribsheet linked to above shows at least some Shimano and some SunTour stuff having the same spacing, but itís not clear to me whether that covers this case.

Specifically, the cribsheet shows the SunTour ďUltraĒ freewheel with same spacing as Shimano HG. It also list SunTour Microdrive with variable spacing, but it looks like those were cassettes, not freewheels. But I canít tell whether the cribsheet purports to be a complete list of all possibilities.

Since I am planning to replace this bike soon (but keep it as a backup/winter bike), Iím reluctant to put a lot of money into replacing the whole system.
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Old 07-02-20, 11:02 PM
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Why don’t you just measure the cog spacing? Someone can correct me, but I thought Suntour freewheels had a threaded 1st cog. I know the ones from the early 80’s did. Just take the cogs and spacers off the freewheel body and measure them.

Cog spacing can be debated as to who is right, but the proof is in the actual freewheel.

I use a 2x6 cit 6” long. Put a couple of lag screws in it to hold the large cog, pit it in a vise, and use a chain whip to unscrew the cog(s). I do this with Sachs Aris freewheels to lube them and swap out a cog or two.

Just use digital calipers to check the spacer thickness. Or set them on a flat surface and compare heights. They will either be the same or not. You could keep track of which ones go where, but the different freewheel body diameters will take care of that.

John

Last edited by 70sSanO; 07-02-20 at 11:06 PM.
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Old 07-03-20, 12:56 AM
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Will the Sun Tour rear derailleur work well with friction shifters? If so , and surely it must, you might try a pair of the old Sun Tour bar end shifters that everybody loves or the Shimano variant which is, in my opinion, just like the Sun Tour, only better. There is a current Dia Compe which some claim to be the best every. Best bar end shifter that's ever been in a bar. I prefer the Shimanos.

I understand that throwing away 35 years of bicycle technology and going back to what worked well in 1975 may seem a bit curmudgeonly and I do like the nice click of the modern indexed systems, but with just a little bit of practice, I find that I can find that same 1975 feeling all over again. Makes me want to drink a case of beer and party.
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Old 07-03-20, 11:58 AM
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I looked around a bit for the calipers I once had, but couldnít find them. So I took a 3 mm allen wrench to test the gaps between the cogs and found that some of them did indeed appear to be just over 3 mm and some just under.

So I looked at some of the eBay listings for new/old SunTour stock, but they were a little pricey. And you never know how much to trust an eBay sellerís description.

So I went to a local shop that seems to have gone over mainly to secondhand bikes and repairs, thinking that if anyone had an old SunTour freewheel sitting on a back shelf, it would be them. Unfortunately, they did not (though the owner did rummage around a little thinking they might).

Since I had the bike with me, he said ďletís just pop this off and see how a Shimano worksĒ. He pulled an ďalmost unusedĒ MF-TZ21 off a secondhand bike and replaced the freewheel. On the first test the shifting was a little crunchy, but after some adjustment it worked smoothly. Then we put on a new chain I had brought, and it worked even better.

Of course, that was just riding it around a parking lot, so I wasnít entirely confident about it. But today I did my favorite short local ride, a ten-mile mix of asphalt and gravel, with some ups and downs, used a wide range of gearing, shifted under load, and so on. Everything seems great.

Not sure this would work in all cases, but it worked for me.

Itís also the kind of place where you go back into the workshop with them and chat and pick up pointers, which is a big plus in my book.
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