Kontact 

Well, "put them in my hands, again" since I have already fooled with this plenty. As have the folks on Sheldon Brown's site.

You didn't even manage to post a picture of the .2mm difference between the spacing you measured with a ruler. Why are you convinced that a .2mm difference exists when no reference says it doesn't and you only measured .1mm?

The Golden Boy 

You used to live here!

I moved to Waukesha in 2003-ish. By the time I was interested in bikes- Spring City had been bought by Cyclesmith- they had a store in Delafield too, I think... Anyway- they closed last year or the year before. It sucks because they were close and the guys there were very nice.

It's a pottery shop now.

clubman 

Are you really going to dispute the .2 mm diff because of my pics? Or did you just want to take a shot at me. Ad Hominem appears to be a thing with you.

Why not attack masi61 as well? He's got asymmetrical spacing and it's a cassette too!

Go here . They call it variegated spacing.

Whatever.

Kontact 

Just to put this in some perspective, for the supposed 4.8mm spacing of the last two cogs to make a difference, the system would have to be sensitive to a misalignment of the upper jockey wheel by the thickness of a sheet of typing paper - .2mm.

So 4 prong freewheels may be slightly differently spaced on the last two cogs, but the gross error is going to be one paper thickness on cog 6 and two sheets on cog 7.

Normally, when stuff doesn't index correctly, it is because of the additive effect of all the cogs being slightly off - like when you try to use Campy 8 on Shimano 8, and by cog 5 you're off by .6mm and by 8 it is a 1.2mm error (assuming the indexing was centered on cog 2). The best you can do is to center on cog 4 and get a .8mm error on cog 8. But that's not what would happen if the first cog with shorter spacing doesn't fall until cog 6 of 7. That's why, regardless of whether there is a spacing difference or not, it doesn't cause problems when you throw a Shinano spaced freewheel on - the index system just isn't precise enough to make it matter - especially since even a slight downshift bias will further erode the 6 and 7 cog error.

I would bet that the vast majority of people who have reported a problem were either mixing the shifter/derailleurs as well, had a slightly bent hanger, a 2 prong freewheel or just dirty components that weren't upshifting properly.

Kontact 

How did I attack you by pointing out that the pictures don't appear to have a full .2mm of difference between them? Why is this suddenly personal when we're talking about bike crap?


What does Masi6's post about his cassette have to do with Suntour freewheels? His cassette is exactly the spacing Sheldon Brown says it will be.


And "they" are Andy Muzzi, long time proprietor of Yellow Jersey. When I lived in Madison and worked at a different shop, we would sometimes talk about these technicalities. He loves these kind of gotchas - whether they amounted to a real problem or not. No one else in the cycling industry calls anything "variegated", which is mainly a term gardeners would use.

He also sells and stocks a lot of vintage Suntour stuff.

dddd

To the OP, I created a modified stack of Shimano cassette spacers to be used with Shimano 7s cassettes with Suntour Accu-7 shifter and derailer.
This was back in 1993 or so, but all of the components I was using were pre- "Plug-'n-Play" (which was Suntour's final version of their mtb components which had finally acquiesced to dealer's demand's for compatibility with Shimano 7s cassettes).
So the OP's Suntour-equipped bike may actually feature Shimano 7s Freewheel spacing if it is from ~1994 or later (but not much later because they went out of business about a year after that).
Perhaps these last-version Suntour 7sp Plug-'n Play bikes are what leads some to believe that Suntour 7s Accushift freewheels are similarly interchangeable with Shimano-7 SIS cogsets. By this time I believe that most of Suntour's parts gruppos would have been for MTB and hybrid use, and with most of those being mid to lower-level components.
Suntour's presence in the market had seriously shrunk by this time however, making such bikes somewhat rare today.

I needed a lightweight cassette wheel for my Suntour Accu-7 road drivetrain, and wanted to use the SRP Hyperglide Titanium cogs, but discovered that using a Shimano 7s cassette had two issues. First and most obvious was that the cassette spacing was a bit off. It worked ok on the stand, but in spirited riding conditions the shifting was very poor, overshifting to some gears and hesitating on others. I began remediating this by first progressively thinning certain of the spacers, which helped a lot. And, as I recall, I used thicker spacers (also iteratively thinned to exacting standards) for a couple of the spacers on the smaller end of the cassette. Shimano 7-SIS actually has asymmetric cog spacing of it's own, little-known, but the 2-3 spacer (between 2nd and 3rd-smallest cogs) measures a full 3.3mm, versus 3.1mm for the others. Those are the particular spacers that I sourced and fine-tuned to work at the smaller end of the cassette.

I still have the stack of spacers that I finally got to work well under high-effort riding conditions, and can measure them.
Sanding the plastic Shimano spacers, using a dial caliper for confirmation of progress (toward uniform and accurate thickness around each spacer) is quick work, and the resulting cassette worked fine with the stock lockring. Establishing the needed thicknesses of the spacers was very time-consuming work, but this was for my carbon/alloy Epic, which was my number-one road bike back then.

I do advise using only Shimano 9s chain with the final setup, mainly because Suntour's Accushift levers have more "overshift" freeplay designed into each shift movement toward larger sprockets (this to work well with their relatively primitive chain and cogs). That added overshift has the undesirable effect of causing unwanted contact with the next larger sprocket that the one you are shifting to. So back in the day I chose the slab-sided Sachs 7-8s indexing chain because it was slightly thinner than Shimano's HG-91 (and had less tooth-grabbing sideplates) to overcome the overshift issue. The HG 9s chains that later became available work better yet with any Accu-7 drivetrain.

The Golden Boy 

Something like this?


Centurion Pro Tour 15 and The Hawk

dddd

There would be more ways to do this today than back in the early 90's when 9s spacers didn't yet exist.

Oh, and for those who might want to better visualize the spacing variability on Accu-7 freewheels, I use a 3mm Allen key as a feeler wedge. I use the same method when I am quickly trying to separate U-6 freewheels out of a box of random Suntour freewheels, I just insert the 3mm key and twist.
Suntour cogs were not the same thickness as Shimano cogs, so this is just a gross measurement that happens to come in handy from time to time, though I can for the most part visually discern a clean Ultra-spaced freewheel with a glance.

All this reminds me of indexing issues I've had to diagnose due to A) Cable anchored in the wrong position at pinch bolt, B) 3.3mm 2-3 spacer in wrong space between cogs, and C) use of RapidRise shifter or derailer in place of proper original SIS-7 parts (which effectively puts the 3.3mm spacer at the wrong end of the indexing sequence).
Having nailed down these three issues many years ago, flummoxed home mechanics seem amazed at how quickly that I can home in on one of these three mistakes after their local shop has perhaps had their bike for a week only to offer costlier suggested remedies.

Kontact 

This doesn't take into account the variability in the cog thickness. Both produce cog spacing.