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6SP Suntour Accushift lever w/ Shimano 7SP Freewheel+Derailleur;who's really done it?

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6SP Suntour Accushift lever w/ Shimano 7SP Freewheel+Derailleur;who's really done it?

Old 02-16-14, 02:43 AM
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6SP Suntour Accushift lever w/ Shimano 7SP Freewheel+Derailleur;who's really done it?

All,

So Sheldon says that you can get remarkably good shifting with a 6-speed Suntour Accushift shift lever combined with a Shimano 7-speed freewheel (or cassette, I assume) and Shimano derailleur, getting all 7 speeds by using the limit screw as the bottom- or top-end and the index-notches in the shifter for the other 6 gears. With modern chains and hyperglide teeth he wrote the shifting could be even better this way than with New 6-speed Suntour throughout the drivetrain.

Sounds great in theory, and it would solve a problem on a vintage bike o' mine, but I was hoping to hear stories of folks who have actually done this and been pleased with the results.

Care to share your stories?

Thanks,
Warr
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Old 02-16-14, 03:08 AM
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6 index shifter with a 7 speed cassette? you will be short one click IMO, you can't shift more than the clicks the shifter can do.

You can do 10 speed with an 11 speed brifter but you can't do 10 speed with a 9 speed brifter, that is pretty much the same you want to do unless you can force somehow the 6th click in those suntour shifters. Sincerely 1st time I hear about this mix.

I had back in the day one of those suntour shifters and I have now one but is 7 speed so can't test sorry.

If you go friction (like real men do ) you shouldn't have a single problem at all.

Good luck
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Old 02-16-14, 03:52 AM
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6 click's for 7 cog's is just about right isn't it..?
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Old 02-16-14, 07:09 AM
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He's sayin it doesn't need a click, an it relies on the space between the last click in either direction and the dead space after as Suntour shifters have.

Ive never heard of it, though I have heard you can use a 8sp campy derailleur on a 8sp shimano setup by moving the cable to the other side of the derailleur pinch bolt.

Have not tried either though
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Old 02-16-14, 07:13 AM
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EDITED POST:


I currently have 2 bikes running quite smoothly on Accushift 6s shifters to Accushift derailleurs with Shimano 6s FWs.
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Old 02-16-14, 09:08 AM
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Shimano 7sp SIS shifters are cheap and plentiful if the Accushift doesn't work out.
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Old 02-16-14, 11:35 AM
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Originally Posted by jeirvine
Shimano 7sp SIS shifters are cheap and plentiful if the Accushift doesn't work out.

+10 ^^^^^^


As for at least half of the other "facts" that I'm seeing in the above posts, well, perhaps better I say nothing than to say what I know...
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Old 02-16-14, 12:18 PM
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Perhaps the suntour accushift 6 speed shifters pull the same amount of cable as shimano 7 speed shifters. The derailleur doesn't care what brand of shifter it is, only the amount the cable pulled.
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Old 02-16-14, 01:20 PM
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Originally Posted by dddd
+10 ^^^^^^


As for at least half of the other "facts" that I'm seeing in the above posts, well, perhaps better I say nothing than to say what I know...
If I'm wrong, please let me know- I would really not like to be spreading incorrect stuff.
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Old 02-16-14, 01:44 PM
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I did that for my barcycle, a 1990ish specialized hardrock comp. When I got it, the previous owner had managed to break a chunk off of the largest freewheel sprocket. So, I needed a new freewheel and didn't feel like paying ebay prices for a NOS accushift freewheel. I picked up a used shimano real derailleur at the flea market and a freewheel from amazon. It works fine.
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Old 02-16-14, 03:03 PM
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Originally Posted by The Golden Boy
If I'm wrong, please let me know- I would really not like to be spreading incorrect stuff.
You can visibly see the difference in cog spacing between 7s Accushift and 7s Shimano, and that's enough for me to rule it out.

Back when I raced with 7s Accushift Command Shifters, I wanted to use Shimano freehub parts and their lighter aftermarket clones like ti cassette cogs and lighter freehubs.
I absolutely had to re-space the Shimano-compatible cassettes in every case, lest the cable adjustment need a different setting for each end of the cassette.
I sanded down plastic and aluminum cassette spacers as needed, on the basis of repeated road testing.


Now as for the OP using the 6s shifters with a 7s Shimano cog stack, what will keep the shifter from slipping down from the largest to the second-largest cog when there is no detent? Is the rider supposed to hold their thumb on it or change to friction mode whenever a steep hill threatens...

But, If it is a matter of forcing the shift lever past the smallest cog detent, keep in mind that any indexed shifter releases more cable for that last shift to the smallest cog, so the spacer between the 7s Shimano 2nd and 3rd smallest cogs might need increased thickness...

And, get this, Shimano 7s does actually use a thicker, 3.3mm spacer between the 2nd and 3rd smallest cogs, so in this case the whole thing might work quite well...

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Old 02-16-14, 03:13 PM
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Originally Posted by dddd
You can visibly see the difference in cog spacing between 7s Accushift and 7s Shimano, and that's enough for me to rule it out.

Back when I raced with 7s Accushift Command Shifters, I wanted to use Shimano freehub parts and their lighter aftermarket clones like ti cassette cogs and lighter freehubs.
I absolutely had to re-space the Shimano-compatible cassettes in every case, lest the cable adjustment need a different setting for each end of the cassette.
I sanded down plastic and aluminum cassette spacers as needed, on the basis of repeated road testing.

And as for using the 6s shifters with a 7s cog stack, what will keep the shifter from slipping down from the largest to the second-largest cog when there is no detent? Is the rider supposed to hold their thumb on it or change to frictioin mode whenever a steep hill threatens...
EDIT- this is all incorrect other than SIS 6s = Accushift 6s and Accushift 7s is different from everything else.

Was I incorrect about what I posted?

Basicaly I stated that:

as far as spacing Shimano 6s = Shimano 7s = Accushift 6s.

Accushift 7s is spaced differently.

You can use 6 out of 7 of the Shimano cogs.


If any of that is wrong- I'll edit my post(s).
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Old 02-16-14, 03:22 PM
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consider a really wide sideways range of excursion for those center-on RD pulleys ..
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Old 02-16-14, 03:27 PM
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Originally Posted by The Golden Boy
Was I incorrect about what I posted?

Basicaly I stated that:

as far as spacing Shimano 6s = Shimano 7s = Accushift 6s.

Accushift 7s is spaced differently.

You can use 6 out of 7 of the Shimano cogs.


If any of that is wrong- I'll edit my post(s).

Did you actually mean to say that Shimano 6-speed spacing (3.6mm spacers) is the same as Shimano 7-speed spacing (3.1mm spacers, with one 3.3mm spacer between 2nd and 3rd smallest cogs)???

I did respace one just the other day, and my SIS-6 cassette spacers each measured all of 3.65mm.

And yes, Accushift 7s is spaced differently, primarily the largest 3 cogs are noticeably closer together, and as confirmed in Suntour's freewheel charts.

And yes, Shimano 6s spacing is definitely functionally equivalent to Suntour's Accu-6 spacing, and seem to be equivalent to standard older 5 and 6-speed spacing as well.

Suntour Accu-7 spacing seems the same (at the large end) as an Ultra-6 freewheel, and similar to the earlier Suntour 7s, what I think was called New Winner Ultra-7.
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Old 02-16-14, 03:39 PM
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Originally Posted by fietsbob
consider a really wide sideways range of excursion for those center-on RD pulleys ..
Certainly the floating pullies (or narrower chain for that matter) can allow quiet, reliable transmission to a degree of mis-alignment between pully and cog!

But when shifting, the same error will cause shifting to/from one cog to be crisp, while at the other end of the stack the shifting might be very sluggish or will over-shift past the cog you are trying to select.
Usually, a degree of both problems can be spread out and minimized with a compromise adjustment.

This is less of a big deal for casual use and infrequent shifting, but I usually can't wait to get the right parts on there when something isn't quite right with the index compatibility.
I live in the foothills, btw, so shifters get a workout and you're constantly reminded of how well they work and of how much more effort it can be taking to shift whenever the indexing is less than perfect.
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Old 02-16-14, 03:40 PM
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Originally Posted by dddd
Did you actually mean to say that Shimano 6-speed spacing (3.6mm spacers) is the same as Shimano 7-speed spacing (3.1mm spacers, with one 3.3mm spacer between 2nd and 3rd smallest cogs)???
So SIS 7s is neither the same spacing as SIS 6s NOR the same spacing between all cogs?
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Old 02-16-14, 03:51 PM
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My Accushift 6 speed thumb shifters work with a shimano derailleur on all seven gears on the shimano freewheel. I got this idea from Sheldon Brown's site. I'd link, but I think we aren't supposed to. Google "sheldon brown Mixed Sun Tour/Shimano Indexing"
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Old 02-16-14, 03:52 PM
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At 67, I never adopted index shifting went from friction, 6~7 speed freewheels to a Rohloff IGH.

only 'index' *shifter I've bought, recently. is a Sturmey Archer 3 speed , had one in 1960,
my Brompton has one now.

*(shift notches in front, shift motion in the rear.. single cable between)

But I did Shop setup and repair mechanics on the SIS stuff int the 80's . and again this past few summers ..

for the passing bike tourist traffic dropping by the LBS, for the summer season ..


happened to like the old full height teeth , Regina ORO and the like ..
the Hyperglide shifts early so the index shifting is happy,

and some times when you wish it would Not. and ghost shifts..

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Old 02-16-14, 03:53 PM
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Originally Posted by pfaustus
My Accushift 6 speed thumb shifters work with a shimano derailleur on all seven gears on the shimano freewheel. I got this idea from Sheldon Brown's site. I'd link, but I think we aren't supposed to. Google "sheldon brown Mixed Sun Tour/Shimano Indexing"
Great first-hand data point there! ^^^^^
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Old 02-16-14, 04:01 PM
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Originally Posted by The Golden Boy
So SIS 7s is neither the same spacing as SIS 6s NOR the same spacing between all cogs?

Just to clarify, a standard, Accu-6 or SIS-6 freewheel will always be narrower by a couple of mm than any 7s freewheel, but usually either would fit on the same hub or wheel.

6s cog spacing, measured center-to-center is about 5.5mm.

7s cog spacing, measured center-to-center, is about 5.0mm, give or take, between brands.

Try placing different freewheels on a table, then sighting across the gaps between cogs. Easy to see these differences, although the seating surface where the freewheel bottoms on the hub threading may be recessed to a differing degree across the back surface that rests on the table.

I can honestly just look at these different cog spacings and identify what I'm looking at in most cases, unless the cogs are grungy.

Lastly, getting back to the OP's question, keep in mind that the Shimano derailer (other than pre-9sp DuraAce) moves not quite as far as a Suntour derailer for a given amount of cable movement, so this is why the Suntour Accu-6 levers will index Shimano 7s cogs when a Shimano derailer is used.

Most older derailers, and even the very first (Dura-Ace only) SIS levers, have this slightly-higher actuation ratio, making them more sensitive to lever movement.
The most recent derailers (first is was SRAM 1:1, then it was Shimano DynaSys-10, now it's Shimano-11), all have even lower actuation ratios than typical modern SIS derailers. This allows lower cable tension, and is less-sensitive to any incremental increase in cable elasticity, such as occurs over time as cables become contaminated and degraded. Thus, service intervals are increased even with today's narrower cog spacings.
12-speed cog sets will be next, and I doubt there will be any problems if they are using electic-actuated derailers, which suffer no loss of accuracy over time.

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Old 02-16-14, 11:27 PM
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Originally Posted by pfaustus
My Accushift 6 speed thumb shifters work with a shimano derailleur on all seven gears on the shimano freewheel. I got this idea from Sheldon Brown's site. I'd link, but I think we aren't supposed to. Google "sheldon brown Mixed Sun Tour/Shimano Indexing"
PFaustus,

THANK YOU for confirming that this combination works.

I didn't mean to create such a bru-ha-ha over this, but I'm glad to see such spirited debate is alive and well in the Vintage forum. I agree with all the experts here that this sounds crazy (I was a professional mechanic in the late 80's working through college, and we could never mix Suntour and Shimano parts and get a good shift), which is why I was looking for real-world experiences from people who have done it.

So here's what Sheldon has to actually say on the subject, since it seems there are lots of opinions on the subject:

Suntour Indexed Shifting


Older SunTour spacing was very slightly different from other brands, but in practice, you can generally substitute modern freewheels of the same number of gears into a Sun Tour system and still maintain indexing. The superior tooth shape design on newer freewheels will often result in improved shifting despite the slight mismatch in index spacing.

...and...


Mixed Sun Tour/Shimano Indexing

Sun Tour indexed shifters pull less cable per shift than Shimano systems use. Thus, generally, you need to match Sun Tour indexed shifters with Sun Tour rear derailers.
However, it turns out that Sun Tour 6-speed shifters index pretty well with 7-speed clusters if you replace the old Sun Tour rear derailer with a Shimano unit!

The mismatch in cable travel cancels out the mismatch between 6 and 7 speeds. There won't be a "click" for the lowest gear, but the derailer's low-gear limit stop will provide the "indexing" for that gear.

So hopefully, that's puts to bed the notion that you can't shift between 7 speeds with a 6 speed shifter, and apparently, Sheldon might be right that shifts are acceptably good with modern teeth profiles and chains.


PF, I'm probably gonna PM you about some details.

As to why I'm doing this, here's the story: I still ride an '87 KHS mountain bike equipped with 6-Speed Accushift thumbshifters which are integrated into the brake levers (so I want to keep them). I bought it new back in the day. Lately I'm riding with a group that goes through pretty steep hills, and the gearing isn't low enough. The biggest cog in the back is 28T, and the smallest in the front was 28T for 26 gear-inches for low gear. Then I swapped out the front small chainring to 26T for 24 gear-inches for low gear, a minor but noticeable improvement, but I want lower.

I want to keep the wheel and the hub, and the existing derailleur is a bit tweaked and could stand replacing anyway, so after reading Sheldon, I had the thought of getting a Shimano-compatible 7-speed freewheel with a 32-tooth big cog and a vintage Deore XT rear derailleur and new chain. With the 26T chainring, the new freewheel would get me 21 gear-inches for low gear, which would be very helpful.

(And before you say anything about the Shimano 34T 7-speed freewheels out there, they jump from 24T to 34T, which is just crazy.)

Any other personal stories about this sort of hardware combo, I'd love to hear about it.

Thanks,
Warr
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Old 02-17-14, 12:06 AM
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I was sent a private message for more info, but I don't have enough posts. So, here goes:

I don't have a lot of experience with indexed shifting to compare it to, but it seems to work fine. One click changes the gear. It is a shimano freewheel from Amazon - a 28 tooth 7 speed tourney. The chain was a seven speed chain I had in the stash. KLH? The rear derailleur is a shimano light action. I think it might actually predate SIS, but I'm not sure. The seller said it had the same pull as newer derailleurs and it works. Would it work with a bigger freewheel? I don't know. I recently had a deore LX derailleur fall into my hands. If the bigger freewheel appears cheap enough, I might try it.
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Old 02-17-14, 01:16 AM
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i know its not exactly what you're asking and it seems you have your answer but.. i shift 6 speed shimano freewheel with a 7 speed suntour gpx. it is perfect.
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Old 02-17-14, 10:19 AM
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FWIW, I put a Shimano-spaced 7 cog freewheel on my Accushift/GPX Ironman and it shifted like a champ.

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You know it's going to be a good day when the stem and seatpost come right out.

(looking for a picture and not seeing it? Thank the Photobucket fiasco.PM me and I'll link it up.)
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Old 02-17-14, 11:33 AM
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I'm using SunTour Edge 6-speed levers in friction mode, with an 8-speed XTR cassette. I almost broke down & put on those old tri-color brifters, just to get a feel for them, but they're just so doggone heavy, compared to downtube levers, that I had to veto myself.
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