Crunchy-feeling chain - but only in one gear

[mjr]

Fit the old chain ......... if you still have it .............. and see how it runs.

I don't have it, but as noted in the opening post, I'm sure it did it even then, just not as noticeably as with the current one (which is a slightly lower spec... I'll probably find another bike for it, though)

Other than that, and it is an Ultra6, you'll need a narrower chain.

How much narrower? I'd rather not repeat the mistake and searching the fine web didn't reveal the width - Ultra 6 chains seem to be labelled 3/32", same as current 6/7/8 (and stonkingly expensive for New Old Stock). Would you mind waving some calipers at the pins of one of your bits of chain, please?

[Mick F]

Yep.
Will do.
They're out in the shed, and it's chucking it down out there!
I'll look shortly.

From what I feel I know about chains, all derailleur chains are the same width - or thereabouts - but it's the plate profiles and how far the rivets protrude that make the difference.

I do know that Ultra6 chains were needed for the new-fangled 6sp freewheel blocks. I went onto Sedisport chains as they were correct too. I eventually went to Ultra7 and still used the same chains ......... but Ultra7 had an extra cog on the outside. They didn't re-stack the same block.

[Mick F]

Using my digi callipers from Lidl, I find the following:

Outer plate width 6.87mm
Inner plate width 4.37mm
Rivet width 7.35mm

[Brucey]

I am pretty sure that you have a SunTour New Winner freewheel there, built up 'compact/ultra' style with only 5 sprockets (from a possible 6 or 7) . I suspect that someone has robbed the 6/7 pair from your freewheel; these are now like rocking horse poop to get hold of. By contrast the #6 sprocket for a 6s compact is more easily found. I think I have a 13T one somewhere in this fitting NOS.

The compact spacing is 5.0mm nominal, so you should shoot for an 8s chain. A 9s one might work although 9s sprockets are about 1.8mm thickness and these sprockets are nearer 2.0mm, so shifting quality might suffer.

However IIRC all the sprockets bar the two largest are threaded on this model freewheel and this can make for some iffy spacings between the cogs.

What I described earlier (i.e. the #2 sprocket becoming dished) is a real problem with these freewheels and is almost certainly the root of your troubles here.

However there is a cure; if you disassemble the sprockets, you will find that, normally, there is a very thin-walled spacer between the #2 and #3 sprocket, without which the #3 sprocket would (in less than one turn more) bear against a shoulder on the freewheel body. If you cut some thin shims (about 0.5mm total thickness will be required, so about four thickness of coke can) of a size that fits inside the ID of the #2/#3 spacer, to go between the 3 sprocket and the body shoulder, you can arrange it so that when the #3 sprocket is tightened, most of the load goes via the washers into the body shoulder, and only a small fraction of the load goes into the #2 sprocket via the spacer. This very greatly reduces the tendency of the #2 sprocket to become dished; the load required to stop the #1 and #2 sprockets from moving around is only a tiny fraction of that which is otherwise seen.

I worked up this tweak over 30 years ago, when I was using this model of freewheel in tandem time trials. I also used it on my touring bike. I had terrible problems with the #2 sprocket dishing (in both situations) until I did the tweak. The successor model freewheel (the winner pro) used more splined sprockets and wasn't so badly affected in this way.

hth

cheers

[Mick F]

I suspect that someone has robbed the 6/7 pair from your freewheel; these are now like rocking horse poop to get hold of.

Rocking horse poop eh?

I gave my New Winner Pro plus a full set of six sprockets to a mate who was doing up his bike. I still have some bits, but no body .......... but I have the 6/7 pair 13t/14t sprockets ............. and they unscrew.

[Brucey]

you would be amazed how much they would sell for (NOS) on US e-bay....

cheers

[mjr]

Thanks both. I've never had much luck with shims so now I'm wondering if it would be simpler to replace the unit with a modern Shimano-compatible freewheel and offer it up for restoration. Will I be surprised by the hub threading, or only the difficulty of removing the freewheel from the wheel?

[Brucey]

if it has been pedalled on hard enough to dish the #2 sprocket it will almost certainly be a right PITA to get it off the hub.

Only this afternoon I was trying to remove a freewheel of this exact sort (using someone else's remover...) and it was not coming off. I got up to about 150-175 ft lbs and I stopped; at this point we went to plan B. There is little to be gained by breaking someone's tools for them when you are trying to do them a favour....

BTW this was a freewheel that hadn't seen enough torque to dish the #2 sprocket yet, either.....

The hub threading will be standard; I don't think they made a French-threaded version of this freewheel.

cheers

[Mick F]

Mine are well used. Not worn out, but well used.

I went to 7sp because it was the only way to get a 13t cog. I had - and still have - a variety of my Stronglight 99 chainwheels, and my top gear in those days was 53/13 and it was as high a gear as I could afford to buy back then.

In the old days, you could go into a decent bike shop, and they had a display unit with all the cogs in all combinations. I had loads of them back then, and each time we moved house, I would re-gear the bike. We moved a few times in the 1980's and each commute had a different set of hills and required a different set of gearing.
These days, I'll take as wide a set as can get my hands on!

The freewheel body can be difficult to remove. I used to do mine frequently, knowing that it could be a devil to unscrew.

You need the correct tool. Two dog, or four dog depending on the body. I had both, and probably still have them somewhere.
Remove the wheel nut or QR, and fit the tool and replace the nut/QR.
Tighten the tool in a bench vice and loosely do up the nut/QR with the wheel horizontal.
Unscrew by turning the wheel anticlockwise. Expect it to go with a bang as it undoes.

[mjr]

Thanks again. I know from experience that my bench vice isn't up to this - the bench started to move on the last one - but I'm quite expecting to have to bolt the remover on (and I do have the right one) and use the longest wrench, but you never know, I might be lucky this time!

[Brucey]

I went to 7sp because it was the only way to get a 13t cog....

your memory may be playing tricks on you; Sun Tour 5s standard or 6s 'ultra' would allow a 13T top, but 6s standard spaced or 7s 'ultra' (on the same body) would allow 12T top, i.e. using a 12T/13T pair.

cheers

[NATURAL ANKLING]

Hi,
Solution.............get a freehub .....I only have a freewheel on the turbo now.
Something I am happy not to have to un-seize when we got ice before I rush to work.....late as usual

[Mick F]

I'll bow to your superior knowledge there Brucey.

Just checked in the shed.
I have a single 13t outer as well as the 14t/13t combo outer.

I don't remember why I had that, and why I haven't got a 13t/12t combo. Dunno if I ever had one.

[foxyrider]

Use a narrower chain - I had a similar issue with a 6speed suntour block - I run a 10speed chain on it and the problem disappeared (it's the only non kosher part on my Eroica bike) Goodness knows what chain I used 40 years ago as I never had a problem back then.

[foxyrider]

Are you sure you are not trying to run a 1/8" chain or something mad like that? .... Is the freewheel nominally 5.5mm pitch (std 5s) or is it different to that?

I know I do some daft things and I did buy a 1/8" chain at the same time, but I've fitted that to another bike already, the connecting links are very different (3-part link on the 1/8") and I read PC-830 off the side of the fitted chain... so no.

I checked the freewheel pitch with calipers as best I can (using the ID prongs resting against each sprocket in turn, shifting the chain out of the way) and it looks like 5mm, every pair. With the distortion you suggest, it makes me think it would be more sometimes and less others I think I've read SUNTOUR off it before and it's got the two-prong remover slots... and I don't know if you can see it in the photo (blasted camera was determined to focus on the carpet) but there seems to be a lot of thread showing outside the smallest sprocket - could it be an Ultra-6 with only 5 sprockets fitted? Why?

Where does this leave me?

Might have been converted for junior/juvenile restricted gear racing - common bodge if you didn't want to reset the gears constantly. I used to change chainrings to do the same thing.