jeirvine 

Some questions for the freewheel gurus.

1. Are Suntour Ultra 6 spaced freewheels the only 6-speed units that will fit 120 spacing, or are there any modern ramped HG-style 6-speed freewheels designed to fit 120mm spacing?

2. Are Suntour Ultra-6 freewheels evenly spaced enough (at allegedly 5.0 mm between cogs) to successfully index using Shimano 7-speed SIS shifters/RDs, (or Campy 8 speed for that matter). If not, could one even out the spacing using the right spacers? Ref: https://sheldonbrown.com/cribsheet-spacing.shtml#k7fw

I have a pile of Suntour 5-speed freewheels and a corn-cob Ultra-6, and am wondering if it's worth the hassle of making up a wider geared ultra-spaced frankencluster. I've heard that some folks have issues shifting wider geared ultras with friction, and I'm wondering if indexed shifting could do the trick.

(Yes - I know I can re-space a frame to 126, I know that plenty of folks do fine with friction, and I know I can buy a wider geared ultra-6 for $$$ on eBay, but I don't wanna do any of those things on this build for my GF.

Thanks in advance,
-J

Captain Blight

I might be mistaken but I think Ultra became the de facto standard for spacing... so, maybe.

And maybe, the best way to find out would be to set up a bike and try it out. You never know until you do.

jeirvine 

I think it did for 7-speed: Shimano 7-speed SIS is 5.0 spacing. Are modern Sunrace (etc.) 6-speed freewheels spaced at 5.0 for 120, or for 126mm? If 120, then I'll stop right there.

ColonelJLloyd 

No, modern 6 speed freewheels are made for 126mm spacing. As far as I know, the only game in town for 6 speeds in 120mm spacing is the Ultra 6. And, actually, they are best suited for 122mm spaced frames, though the difference is small enough that it's not really a factor.

I use an Ultra 6 in my 122mm spaced Schwinn Volare. It works well and, even though they are well built, the cogs do not shift as well as modern ramped (HG) cogs.

jeirvine 

Thanks. Have you ever tried shifting an Ultra-6 with SIS 7-speed shifters?

ColonelJLloyd 

I have not, but if the Ultra spacing is actually 5.0mm as you say, then I'd expect it work pretty well.

Bill Kapaun

https://sheldonbrown.com/cribsheet-spacing.shtml

ThermionicScott 

I've always figured that Shimano "borrowed" SunTour's Ultra-6 spacing when they decided to go from 6 to 7 speeds.

pastorbobnlnh 

What type of Suntour Ultra's do you have? The spacers of different models don't usually fit each other. The same can be said about the cogs. Also, I don't think they do match up perfectly (but that does not mean that index shifting will not work. I'll try to take a picture of an Ultra beside a 7 speed Shimano for comparison.

Also, take a look at this Suntour spacing gauge. It actually has two different sizes for spacing Ultra cogs.

leaping_gnome

Yeah, I don't think New Winner ultra-6 (for example) are evenly spaced, but can be used under the Accushift indexing. All others are "try and see" experimentation - it may work great! The one other "gotcha" using 6-speed clusters on 120 OLN frames can be very tight clearance between the chain stay and the smallest cog when getting the wheel in-and-out of the horizontal dropout. Sometimes the stack and spacing can be right on the axle but the cog hits the chainstay before the axle can dis-engage the dropout slot. I have this problem on one of my bikes that is 120 spaced and just barely budges out to 122.

Good luck! - Jim

jeirvine 

The ultra-6 I have is a "Winner" (Not "New" or "Pro").

SuperLJ

Maillard (and the lesser Atom) freewheels were also made in a narrow version in 6 & 7 speed. The cogs are all 5mm on center. They are labeled "COMPACT" on the outside end of the body. I've been using a 6 speed one on my 120mm spaced Bertin for ages.

SuperLJ

... with a 14T smallest cog. All kinds of room between the cog and the chainstay.

dddd

Depends on how the hub/wheel is spaced/dished. Many older 10 speeds had a huge gap between the freewheel and the inside of the right dropout and could take a std 6-speed straight away.
Others, especially with Campag hubs, struggle with even an ultra-6 freewheel.

I've used Ultra-6 FW's with 7-sp Accushift shifters to good effect, but Shimano spacing is different.
All Suntour freewheels seem to shift best with 9-speed chain, especially the narrow-spaced ones. The narrower chain should allow good shifting over a wide ratio spread using U-6 spacing!

I've built up a ramped narrow 6-speed FW on a Dura-Ace 7sp body with the smallest cog left off. I was able to use ramped cogs from a Shimano 6-speed freewheel, but had to use a threaded, un-ramped cog to hold the 5 ramped cogs in place. This hybrid fW fit easily on my Raleigh Grand Sports bike with 120 spacing and no hub re-spacing needed.

On my PX10LE with 121mm spacing, I built a wheel to barely fit an IRD 13-28t, ramped 7-speed freewheel. I did the axle spacing custom at 124mm and even had to grind down the axle stop that protruded from the inside of the right side dropout. The wheel is very strong though, no problem, and slides into the 121 spaced dropouts with very little persuasion. It allowed me to use Campag Ergo shifters on the old bike, with a decent climbing gear even still using the original 52/45t crankset.