shoota 

Ok try to follow me on this one. I have a nice set of wheels with a tricolor 7 speed cassette freehub. I tried putting an 8 speed cassette on it but it didn't fit, so I took off the smallest cog and made it a 7 speed cassette, it fits fine. I would like to use these wheels on a bike that has 7 speed Suntour alpha components, including a 7 speed freewheel.
If I threw on the tricolor wheels would the Suntour indexing work? (And don't say try it, the bike in question is currently stripped down for an overhaul.)

I guess the only question is.. is the spacing between the 7s freewheel the same as the one-cogless-8s cassette? (I don't know if the spacing between 7 and 8s cassettes is the same or not, my suspicion is yes they are the same.)

The Golden Boy 

The trick is partially the spacing.

My understanding is @ Accushift plays by different rules than regular Accushift.

Regular Accushift 7 and 8 speed has non standard spacing between cogs. It's not the same space between all cogs.

Do a search for "mrmw centurion hawk" It contains some really good Accushift info.

FWIW- I have 1 bike running Accushift 6 speed shifters and derailleurs on a 5 speed freewheel, as well as 2 6 speeds using Accushift shifters and derailleurs with a SIS freewheel. And of course, the crowning jewel of SunTour shifters with an SIS indexing ring on a 10 speed setup.

SkyDog75

According to Sheldon Brown, spacing on a Shimano 7-speed freewheel or cassette is 5.0 mm and spacing on a Shimano 8-speed cassette is 4.8 mm. They're close, but not the same. I'd expect shifting to work well in one part of the gear range, but the further you stray from that workable range, the poorer shifting will get as each cog further away is an additional .2 mm off.

And that's without bringing SunTour into the equation. Like The Golden Boy said, SunTour Accushift indexing used irregular cog spacing -- the cogs were slightly closer together at one end of the cluster. Some people claim to have mixed Shimano and SunTour drivetrains with varying levels of success. Some say it works, some say it kinda works.

If you were going to try this, I'd suggest to make sure you're using a rear derailleur with a floating upper pulley (e.g. Shimano Centeron), which may be more tolerant of the variables in such a mixed system. Even then, I don't know how confident I'd be that you'll wind up with a bike that shifts flawlessly.

The Golden Boy 

Yes!

I should have been more specific- 6 speed Accushift is spaced the same as SIS 6 speed, the same as 5 speed. But the cable pull is different- you have to match SIS with SIS and Accushift with Accushift. But at 7 sp, it's possibly fudgeable to change the cable pull on an SIS unit by using the alternate cable routing, and then the Centeron pulley does the rest of the fudging.

shoota 

I think I may have ran across your 10 speed ring in my searching, way cool I must say. Thx for the heads up on the search.

Ah bummer, I read his website but must have missed the info about the spacing being different between 7 and 8 speed, I really thought they'd be the same.
I'm surprised to hear you say that Accushift uses wonky spacing in the freewheel, I was under the impression that all 7s speed freewheels were essentially standardized and brand independent.

shoota 

There will be no fudging here, I'm not buying additional parts. I'll either get what I have to index or switch it over to friction. But I REALLY want index!

nfmisso

First: get some calipers so that you can measure yourself. The 6" ones that HF often has on sale for $10- are fine.

Then using Sheldon Brown, and other resources, you can determine how to build a custom cassette that will have the spacing and gearing that you want.

shoota 

I actually already have digital calipers and will measure tonight. I had no idea that Suntour cog spacing wasn't uniform so I didn't think to measure it last night when I had it all out.

ThermionicScott 

I've got some extra 7-speed Shimano spacers if you'd like. Per Sheldon, they should be 3.15mm thick, but I don't have a good way to measure them that accurately.

shoota 

Ok cool man thanks, I'll let you know once I figure all this out.

The Golden Boy 

I didn't see if you actually noticed it (because I used @ instead of "Alpha") but Suntour Alpha Accushift is different than Accushift.

I think it's that Alpha shifters must be paired with Alpha derailleurs, but I don't know if there were special Alpha freewheels.

pastorbobnlnh 

Not certain if this helps, but I have worked on Suntour freewheels which were marked with "Alpha."

rhm

+1. Lots of good points in that post, but this one was near the end so I quote it just in case anyone missed it.

shoota 

I did notice. I don't believe the shifters have an "α" on them. They just say Accushift. However, the catalog lists everything as "Suntour Edge" (freewheel and chain are listed as "Alpha") so I would expect everything on this bike to work together since it appears to be original.

https://bikecatalogs.org/SCHWINN/1989...89_Ltwt_16.jpg

shoota 

What I'm reading about 7 speed Suntour spacing doesn't seem to jive, I must be missing something.
This is from mrmw:


and this is what I've found elsewhere:
"For 7 speed, the top 2 spacers are
3.3mm (some of them are even labeled "3.3mm 2nd position"), the bottom 4
are 2.8mm, and the cogs are 1.9mm thick, for an average of 4.87mm."
Taken from here: https://groups.google.com/forum/#!to...ch/A-N4DrtpISo
and https://sheldonbrown.com/gloss_sp-ss.html#spacingk7

RoadGuy

I don't get what you're trying to do. Why would you try putting an Shimano 8-speed cassette on a Shimano 7-speed freehub, with SunTour 7-speed Edge shifters (and derailleurs?)?

I actually tried this to see what would happen as I was upgrading my Trek 1100 from Suntour Edge 3 X 7 shifting to Shimano 3 X 8 shifting. I got the Suntour Edge Shifters and derailleurs to work with a Shimano 7-speed freehub and cassette, then switched to a Shimano 8-speed freehub with 7-speed cassette and spacer (still working), and then switched to Shimano 3 X 8 downtube shifters, and 8-speed cassette and eliminating the spacer on the freehub.

I'd say that you can get the Suntour Edge 7-speed downtube shifters and derailleurs to work with a Shimano 7-speed freehub and cassette. It will not work as smoothly in Index Mode as Shimano 7-speed Index shifters, because of the difference in the way that Suntour shifts (non-linear) but it will work.

You can also used the Shimano 8-speed cassette on a Shimano 7-speed freehub wheel. BUT YOU WOULD HAVE TO REPLACE THE 7-SPEED FREEHUB BODY WITH AN 8-SPEED FREEHUB BODY (ABOUT $10-$15). Then you would need to get a set of 8-speed shifters, if you use 8-speed Index shifting.

If you are going to go with friction shifting, you can use the Suntour 7-speed Edge Shifters with the Shimano 8-speed cassette and all 8 cogs, but you will still need to change to the 8-speed freehub body. If you don't mind friction shifting, all you need to buy is the 8-speed freehub body.

miamijim

IIRC anything with an 'alpha' is interchangeble with the exception of 2000 series alpha.

Cody....7s Tri-color is built on a 126mm hub with a shorter freehub body than 8s. 8s cassettes will only slide on if you remove one of the cogs.

Keep this in mind when mix n matching Shimano and Suntour and Campy..... Chevy wheels do NOT fit Fords.

miamijim

https://equusbicycle.com/bike/suntour...20-%200008.pdf

AlexCyclistRoch

Answers:

I've done 7-sp with 8-sp shifters: What should work is adjusting you derailleur PERFECTLY on the center cog, and let the pulley float take care of the rest.

As far as that graphic goes...larger cogs are thicker down by the splines.

zukahn1 

Based on a couple of bikes I have had I can say the 7 speed edge group is Alpha type and will work fairly well with 7 speed Shimano spaced freewheels cassettes have 5.0mm spacing, the Sachs LY freewheels were a pretty common replacement in the 90's. They won't quit work right with a 7 of 8 setup which gives you 4.8mm spacing leaving you about 1.5mm off at the end of a 7 speed shift range, which is just bit too much for indexing.

Sheldon Brown's Bicycle Frame and Cassette Spacing Crib Sheet

shoota 

Because that's what I already have and don't wanna spend any money.

shoota 

Yep, that's exactly what I did!

shoota 

Well I put the bike all back together and put on new cables and housing.
Verdict: The 7s Suntour freewheel indexes ok. I have to massage one of the cogs sometimes but it's not bad.
The 8s-turned-7s shimano cassette shifts awesome! Smooth, quick, and quiet every shift. Like it was made for it.
So with that in mind, if I need to get a new chain which one should I get?

speedy25

I just had to deal with a accushift problem on a Trek. I solved it with different shifters and a Shimano freewheel, just because those were the parts we had sitting around.

-SP