I was under the impression that you could NOT use a Shimano Freewheel in conjuction with Suntour Accushift shifters?

Just for giggles I removed the Suntour 4 prong freewheel 1988 original 13x26 and spun on a Shimano 600 freewheel MF-6208 13x24 and it shifts flawlessly in Index mode with no adjustments at all? Is there something different about this Shimano Freewheel as compared to others?

I've generally had little problems mixing and matching with 6 or 7 speeds. I think the spacing is pretty similar between Suntour and Shimano. Indexing on a Shimano HG with 7 speed indexed Suntour barcons works great on my touring bike.

It probably depends on the brand of derailleur too.

So what are the "mix and match" possibilities?

I'm assuming I can use a Suntour Winner with my Shimano Z series stuff- it's all friction...

The shifters are Suntour (Accushift) set to Index mode, rear derailleur is Suntour as is the front derailleur. I just foud it odd that it shifted flawlessly, and with zero adjustments.

According to Sheldon, the "regular" 6 speed should be 5.3mm and the Accushift should be 5.5mm.

Assuming the derailleur is lined up on the small cog, it should be over-shifting an additional 0.2mm each shift, times 5 shifts or over by 1.0mm on the large cog.

Maybe this is improving down shifting

No, it's not improving down shifting, it shifts perfect. All I can say is that it shifts perfectly with either the original Suntour or the Shimano Freewheel.

Have you taken it out yet? For me, it shifted perfectly on the stand and then when I rode it and put pressure on it, the chain would skip. It took a while to get the adjustment right. I just lined up the derailleur to make it shift perfectly between the 3rd and 4th or 4th and 5th so that it would not throw the adjustment off too much at the extremes -- The chain stopped skipping this way.

Things wear and change, and we're not talking about NASA tolerances or manufacturing precision. Nothing surprises me anymore, despite what the manuals or standard references might say.

Is there a chart perhaps with compatability? I've got a Shimano 600 mf-6208 that I'm looking to switch out (for different ratios) and I'm finding 6-speed Suntours online that *look* like they'd work but I'm just not sure.

In my past bike shop experience, I also found out that a Shimano 6 speed freewheel worked fantastically with the Accushift system.

One day, probably some slow day in January, I want to take some of my Accushift stuff into the bike shop and do some mixing and matching and see what happens. I think that would be a few hours well spent. There's a lot of variables that need to be accounted for. I used to think that only Suntour 4-prong would work, but I'm coming to believe that the chain choice might be the key ingredient in the mix.

I am not surprised that this works fine. Suntour cog spacing varies somewhat between the small and large cogs, but on average it is close to Shimano 6-speed spacing. I am looking at a Suntour and a Shimano Uniglide freewheel right now, and overall it is close - within the tolerances of indexed shifting.

What confuses most folks (including shop guys) about indexed shifting is that they assume that all shifters and derailleurs behave the same. Wrong.... Suntour and Shimano shifters pull different amounts of cable per cog. And the derailleurs behave differently in terms of how much they travel per unit of cable pull. But index-compatible cog spacing is relatively close between the makers. That is, 6-speed freewheels are generally cross compatible, as are 7-speed freewheels. Of course, if you have 6-speed shifters, they are not going to correctly shift a 7-speed freewheel.

To improve your shift performance, now remove the Shimano 600 freewheel with Uniglide cogs, and install a current $15 Shimano Hyperglide freewheel. The Hyperglide cogs, when matched with a current chain, results in much better crisper and faster shifting than Unlglide ever did.

This is kinda odd while they work allright in most cases with Shimano freewheels 6 speed seems to be more compatiable than 7 they usually take a lot of adjusting twinking and are often never quit right.

Okay, here's what I can do about this:

I've got a Superbe Pro RD-00 that has more than enough throw for 8-speed, and a Cyclone 7000 I'd like to try; as well as an XC-D unit; Shimano RDX, 105, Ultegra and XT mechs; And a Sachs Quarz MTB rear derailleur.

Cogsets I have are Suntour 6 and 7 speed 4-prong; Shimano 6 and 7 speed freewheels; Shimano 7 and 8 speed cassettes; and Sachs 6 and 7 speed freewheels, both ARIS and LY 9x. I *might* be in posession of Suntour 8-speed cassette by January, who can say what the world will bring?

For shifters, I have Shimano brifters, 105 in both 7 and 8 speed; Suntour Command Shift in 7 speed; Shimano DT shifters in 6 and 7 speed indexed, and a set of 8-speed barcons; and I think I might have a set of Sachs DT shifters in 7 speed indexed but I'd have to check, I think I might have swapped those out. I know I have a set of Sachs pre-SRAM gripshifters but those are a PITA to mount.

Testbed would be my Trek 560. I can test Sedis, SRAM, KMC and Shimano chains in new or near-new condition.

Question: Have I missed anything, or will this be enough for a fairly comprehensive test of what works and what doesn't?

I didn't catch whether the OP is using a 6-speed Suntour Accu system(?).

The spacing between cog centers is the same for Shimano SIS-6 and Suntour Accu-6. Thus, the two are interchangeable.

Suntour's 7-speed freewheels (and U-6 freewheels) is where the bigger cogs were spaced more closely than the smaller cogs, so there is a visible difference there from Shimano's 7-speed freewheels and cassettes, and interchangeability between brands is what you would call "class B" as far as index compatibility.

Ummm... bicycles are simple machines, and the behaviour of index shifting is easy to predict. I do all forms of unholy mixing & matching of indexing systems, and I find that physical testing not required to determine if a combination of shifter, cogset and derailleur will work correctly together. But you do need to have very accurate numbers for each of the drivetrain components.

For the shifters you need how much cable the shifter pulls per cog (A). Then you need the mechanical advantage of the rear derailleur (B). That is, how much distance the derailleur travels laterally across the cogs for each unit of cable pull sent to it by the shifter. Then you need to know the spacing of the cogs (C). If A x B = C (to within about 0.2mm per cog), then you're in business. I have never had this calculation fail to produce great shifting.

Fortunately, the necessary numbers are archived on the CTC website. Suntour Accushift derailleur mechanical advantage is about 1.83:1 (same as pre 9-speed Dura-Ace); that is the only remaining number that you need.

Oh, yeah, THAT'S a load of fun. Probably won't get my hands even a little dirty or drink any beer with friends while I'm accessing the archives.

Those actuation-ratio numbers quoted on the CTC site aren't anything more than reference approximations.

1.4, 1.6, whatever, these are not numbers intended for use in calculations, and, as such, will not produce very accurate results.

Most of the other numbers on the CTC site are all usably exacting, and in fact can be used to easily prove what I just said.
One exception to thier accurate numbers is their spacing spec for Shimano 7-speed, which actually uses a thicker (3.3mm vs. 3.1mm) spacer between the 2nd and 3rd-smallest cogs. It's a small difference, but one that is quite obvious to anyone who has tried to use a Rapid-rise derailer with a Shimano 7-speed cog stack, enough to make the usual cable adjustment compromise somewhat maddening.

There are some important fundamental differences between Shim/ST indexing systems that make successful parts mixing more than simple cable pull and cog spacing, critical as that is. There is also a difference between what may work for us with random components and a bike in our stand today and what happened in a production environment 30yrs ago.

Shimano indexing precisely centers the guide pulley under the cog with every shift, in both directions. The cog tooth profile helps grab the chain before the guide pulley is centered, and the floating guide pulley both keeps the drivetrain quiet and helps compensate for out-of-spec tolerances throughout the drivetrain. Shifting is smooth, fast and quiet, and the system is fairly tolerant of incorrect cable/casing, less-than-ideal chains, long rear drop dimensions, etc. Dealer setup is fast and easy, and the bikes don't come back frequently needing adjustment.

Suntour couldn't use Shimano's cog tooth profiles or floating guide pulley without infringing patents, and their indexed components were rushed to market in desperation after a disastrous 1984/1985 sales season. That was the year of "Doesn't click, doesn't sell." Dealers couldn't get enough road bikes with Shimano 600 SIS, and thousands of road bikes with Suntour Sprint sat unsold.

Suntour indexed downshifts relied on a little bit of overshift built into the lever to make sure the cog has the best chance of picking up the chain, with the guide pulley hopefully settling into a centered position after the lever is released. Upshifts depend on precise guide pulley/cog alignment and the inertia of faster chain travel onto smaller cogs. The system was very intolerant of mis-spec'd components and frame dimensions, it generally shifted slower, had a narrower range of adjustment, and took much longer for dealers to setup. Customers came back for adjustments far more often. Accushift was very soundly rejected in the marketplace, and as Suntour lost spec they died.

There are additional wrinkles. I'm not sure what the CTC archives say, but Suntour R&D acknowledged three distinct rder shifting geometries, which they tried to cover with one lever spec. They also initially shipped tens of thousands of out-of-tolerance freewheels. US dealers were shipped go/no-go gauges to check cog spacing, and were asked to insert microshims between cogs to correct spacing. Suntour dealer support had to ship dealers improved chains and freewheels for new unsold and recently-sold bikes, and Suntour had to send teams to OE warehouses to rework bikes before they shipped to dealers. It didn't take long for dealers to demand product managers only spec Shimano.

Having lived through all of this I can never find any personal enthusiasm for Shim/ST mixing. I'll never discourage anyone from trying, have fun!, but consider it a gift if it works, and maybe don't assume if the math seems to work the parts always will. Shimano got it right but Suntour never did, and there's more real-world reasons for it not to work than to work.

I'm running a 6 speed Shimano FW with 6 speed Command Shifters with an XC Pro RD. Works great.

I have had to adjust the cable tension a bit more than I was expecting to. I have attributed that more to longer, new cable more than anything else.

I have a Suntour accushift rd, and two different wheels. One has a Suntour freewheel and the other Shimano. I can only get it to index properly with the Shimano freewheel.... But then I'm using Dura-Ace bar ends for 7 speed. My franken-combo is more Franken than most!

OK: here are some very precise derailleur mechanical advantage values:

• Campy pre-2001: 1.43:1
• Campy post-2001 1.50:1
• Shimano MTB and road: 1.67:1
• Shimano old Dura-Ace: 1.83:1
• Sachs New Success (early 90's): same as old Campy. Contrary to a bunch of misinformation on the web, these derailleurs and shifters are functionally equivalent to old Campagnolo

Here are numbers that I am trying to track down:

• Latest Campy 11 speed: ? Advantage is greater than the 10-speed versions? ... I need this number.
• Shimano Dyna-Sys ?
• SRAM ESP: No, it is not 1:1, but more like 0.8 to 1. I need an accurate measurement.
• SRAM road: ???

Wisdom comes in knowing the numbers.

"Sachs New Success (early 90's): same as old Campy. Contrary to a bunch of misinformation on the web, these derailleurs and shifters are functionally equivalent to old Campagnolo"

Thanks for the numbers data, I had not seen that before!

As far as the New Success derailer, I remember having a contemporary-looking, good-quality version of of one of their derailers in the early 1990's which was absolutely spot-on in an otherwise entirely Shimano 7-speed system.

Perhaps mine was one of the MTB versions for compact drivetrains, as it did have a short cage iir, but the faceplate markings were just painted on and had all rubbed off.

There were also Sachs Ergo equipped road bikes, which used the Shimano SIS cable actuation ratio but which indexed over the slightly-different Campagnolo freewheel.

If it's any consolation (I think it is), the rather difficult setup issues that you have correctly outlined in good detail are somewhat remedied by the availability of more-modern chains.
In particular, the overshift-sensitivity that you mentioned is lessened greatly by use of a modern 9sp chain on the 7s Accushift systems, to the extent that I can hardly find fault with my command-shifted setup ridden back-to-back with contemporary bikes.
I also don't recall Suntour having offered any sealed housing ferrules back then, which can do so much for the service interval of the cabling.

I thought that the 6-speed Accushift systems were relatively robust back then when the proper chain was used, but the 7-speed Accushift systems really begged for a narrower chain, mainly to deal with Suntour's narrowed spacing between the bigger cogs.

Having raced on their 7-speed indexing systems in the early-to-mid 1990's, I would tension the shifter screw as tightly as possible to better control the overshift, but I would have really liked to have one of the subsequent even-narrower chains instead of the IG and Sachs 8s chains that I preferred.

I made my own cassette spacers and used a Titanium cogset on a narrowed Nuke-Proof ti freehub to work with those 7s Command shifters. I bought everything cheap at the Encino Velodrome and other swap jumbles.


I even modded my Superbe Pro rear derailer to float as a full servo-panta, by discarding the b-tension screw and internally adjusting the cage spring tension to optimise the chain gap.

Somebody tell me it was worth it!

On my Vitus 979, I have a Franken setup right the way through. Accushift, Record crank and Sugino 75 FD up front ... a SunTour MTB RD (XC) and a Shimano 6 FW on the tail. Things were not going well in friction mode. There was some auto-shifting, and I was hunting for the cog. Maybe some shims are worn. So I switched to index, which I expected not to work. So far, it works nicely. Rather surpirsing, but there you are.