Pompiere

According to conventional wisdom, this shouldn't work, but I was changing a worn shift lever anyways, so I thought I would give it a try. I have a Shimano 600 tri-color derailleur with a 7 speed hub. I used an Accushift 6 speed lever, figuring it could friction shift the low gear, since there isn't a hard stop on the travel. Much to my surprise, it shifted perfectly, up and down the range, at least in the stand and for a quick ride in front of the house. I'm going to give it a proper road test today to verify.

dedhed

What freewheel?

70sSanO

Interesting. Suntour, and others, had 5.5mm spacing on 6 speed freewheels and cassettes.

Evidently the consistent (?) cable pull of the Suntour 6 speed aligns with the Shimano RD actuation and 7 speed 5.0mm spacing.

I imagine this has been stumbled upon somewhere in the past. Using a 6 speed index shifter for a 7 speed freewheel/cassette is probably an odd enough duck that few have tried it.

Good job.

John

dddd

Exactly as expected.

The Suntour (non-3040 series) Accushift derailers had about the same actuation (motion ratio) as early Dura-Ace SIS and also similar to most Suntour and Shimano friction derailers.

So it makes sense that the added cage movement (versus Shimano non-Dura-Ace SIS) allows it to work with a 7s lever moving the chain across a 5 or 6-speed freewheel having wider cog spacing than a 7s freewheel.

It won't be quite perfect as far as the shifting response being the same from one end of the freewheel to the other, but with only 5 or 6 cogs it should work fine for less than demanding riding conditions. Choice of chain and freewheel will also pay a role, as does the derailer's floating top pulley.

Pompiere

Seven speed Shimano Free Hub

Murray Missile 

I've run 6 speed Accushift with a Shimano SIS 6 speed freewheel and an 8 speed chain. Worked great as long as you paid close attention to trim adjustment.

dddd

All brands of standard-spaced (not "compact" or "ultra"-spaced) 6s freewheels have identical cog spacing, so can be interchanged with little effect on indexing performance. Some feature indexing-friendly cog tooth shapes and some do not.
I prefer either Shimano Uniglide or Suntour Alpha freewheels from among vintage offerings, but modern ones work better with indexing.
Either brand will work with 6s indexing, but modern "hyperglide-style" freewheels should always be used with any kind of shifters that allow shifting while the rider is off of the saddle!

The 8s chain width seems to be the go-to for older and/or cheaper 6s indexing drivetrains, Shimano even discontinued their older 6s-width chain when their narrower 7-8s chain went into production, even as they went on making 6s drivetrains for decades after.

ShannonM

No Suntour parts involved, but I can report that a 7 speed Shimano XT thumbshifter indexes a 9-speed XTR rear derailleur over an 8-speed SRAM cassette just fine. The overtravel built into the lever below the 1st click is enough to use the low limit screw as the indexing point and have everything else just line up. A bit fiddly to set up initially, and you lose the ability to make a bail-out downshift under load since you eat up most of the overtravel, but once settled in, it worked perfectly on my mountain bike for years.

I'm not surprised that your 6 speed Accushift levers work with a 7 speed Shimano cluster. If the actuation ratios are anywhere close, the same mechanisms would be in play. Maybe even moreso, because if memory serves, Accushift had overshift built into every gear, and the shifting depended on its being used. (I think Shimano's killer app, the thing that made Accushift and Syncro suck by comparison even with matched parts, was that SIS could be shifted while coasting, and as soon as you started pedaling, it just shifted. Suntour and Campy didn't work that way.)

--Shannon

Murray Missile 

Not according to what I've read in countless threads and articles and experienced first hand. There is a slight difference, enough to cause issues on 6 and 7 speed indexing systems.

Pompiere

So, last night I did 25 miles on my usual route to test the shifting under load vs. in the stand. Every shift was quick and precise, with no delay or noise. There was no wind and the biggest hill is the Turnpike overpass, so I didn't spend much time at the high or low ends, but overall, I was happy with how well it worked.

canklecat

Did the 6-speed Accushift lever for the rear derailleur have two index settings? My GPX 7-speed downtube lever does. I've never used the alternate setting, not sure whether it would work with non-Suntour derailleurs.

WGB 

In a similar vein, saving starting a new thread.

I have an 6 speed Sante Accushift set up on a Schwinn Peloton. It has the Rd, Fd and shifters. Unfortunately I do not have an Accushift freewheel.
I can friction shift but it will not run as indexing. I will install an 8 speed chain "shortly" as ordering tonight along with SIS housing and shifter cables but stumped on a reasonably priced freewheel. I had an Accushift cassette but foolishly gave it to someone who needed it.

Can anyone recommend a specific freewheel or cassette that would index shift? I'd like full model name or model number to help the internet search please.

Murray Missile 

For future reference:

Sheldon Brown Freewheels/Cassette comparisons

canklecat

Double check your components. Sante should be Shimano. It may not be compatible with Suntour's Accushift components.

Regarding freewheels, I've had good results with SunRace brand 7-speed freewheels, specifically the chromed MFR30 (13-25) and MFM30 (13-28). I'm not sure whether SunRace makes a 6-speed equivalent to those. But the tooth shape is excellent and works better on my Suntour GPX Accushift and Shimano STI setups than the original Suntour and Shimano brand freewheels.

WGB 

canklecat and others
Sorry, just tired.

I don't know why I typed Sante, I meant Suntour 7000. Still means 6 speed Accushift system.

WGB 

For posterity, according to Suntour's "Accushift no fault shift insurance", the Accushift system provided, "Non indexed shifting with any freewheel, regardless of sprocket spacing, and most derailleurs, regardless of brand'.


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johnnyace 

On my 1985 Peugeot PXR80, I have Suntour Accushift bar ends running Shimano 105 front and rear derailleurs, with Shimano Golden Arrow cranks/chainrings and a Shimano 9-speed cassette. Somehow, everything works really well together.

EDIT: Thought I should qualify this with the fact that I'm using friction mode, rather than index, but I suppose that's probably assumed.

canklecat

Yup, in friction mode pretty much anything can go together. I have a Shimano L-422 retrofriction type downtube shifter set just for that purpose. Works great. But once an Accushift system is set up right it's good.

For a few years I've had a Centurion Ironman with the Suntour GPX Accushift system, one of Suntour's final Accushift groups. It's comparable to the Shimano 600 Tricolor group of the same era. That bike was finicky to shift and ride with the original Suntour chain (a surprisingly crudely made chain) and Alpha 13-24 freewheel. Switching to the SunRace MFR30 or MFM30 freewheels and KMC Z72 chain gave me crisper shifting and a smoother, quieter chainline. It wasn't really the major Accushift components that were finicky, but the chain and freewheel. Unfortunately KMC has either discontinued or renamed that chain, so after I run out (I have a few spares) I'll need to experiment with other chains to find one that works as well with that bike.

The Alpha freewheels are fine in friction mode, but shifting was a bit clunky and noisy with index shifting. I'm guessing the somewhat squared off teeth produced a slingshot type effect, with the original chain and teeth catching for a split second, pivoting the rear derailleur cage a bit before completing the shift, with the stretched/compressed springs suddenly releasing and snapping into position. It was loud enough that on group rides at least one person would comment on the clunking noise. With the better configuration of the KMC chain and SunRace freewheel, that problem vanished. The only sound I hear is the indexed right/RD shifter snicking into position.

WGB 

canklecat Is this the chain you had??

https://www.amazon.ca/KMC-Z-72-7-8sp...8083077&sr=8-1

top506

Pretty much squares with my experience with the GPX equipped Ironman. Click...CLACK...THUNK!. Sunrace freewheel helped mightily.
I have had very good luck with a Sachs Aris freewheel working with the Accushift/Edge group on my '89 Black Lightning.

Top

WGB 

I found I have an NOS Suntour 7 speed Accushift cassette (Model CS-AP00-S7U). Very tight cluster, has 12-21.

New to cassettes so have to ask.

If I installed it and the group set is 6 speed indexing, could I adjust Rd so it runs just 12-19 or preferably 13-21? Building bike for my son and he's adverse to friction shifters having learned to ride in the indexing world.

ZudeJammer

similar thread here if you want more information: https://www.bikeforums.net/bicycle-m...0-6-speed.html
I got my info there to try it and it does indeed index without any modification

masi61

Do you have the compatible SunTour Accushift 7 speed cassette hub that accepts this cassette?

Just curious what cassette hub you are wanting to use this on.

WGB 

masi61
So now I need a specific Accushift hub?!?!!! Suntour Accushift cassettes had custom hubs? I should not have got up this morning.

Ok, maybe I'll try another cassette or freewheel 1st but might have to consider running another drivetrain

The Golden Boy 

If you have 6 speed Accushift shifters and an Accushift derailleur, you should be able to use a regular SIS/Sun Race 6 speed freewheel. Not Ultra- just a regular run of the mill 6 speed freewheel.

I've used the 6/7/8 speed Shimano chain and SRAM PC870 chains.


Regular Shimano FW:

1985 Trek 620 by Dave The Golden Boy, on Flickr

1985 Trek 620 by Dave The Golden Boy, on Flickr

1986 Trek 400 Elance by Dave The Golden Boy, on Flickr

SuperbePro400 by Dave The Golden Boy, on Flickr