I have noted a number of posts stating that the internal width of 8, 9 and 10 speed chains are all identical.

Per both the Wippermann and KMC web sites this is not correct. 8 speed is 3/32" while both web sites list the internal width of their 9 and 10 speed chains as being 11/128. A small difference of about .008" or .2mm but they are narrower internally.

SRAM does not list internal width for their chains, nor do Campy or Shimano that I was able to find. I would presume though that they are the same as KMC and Wippermann for compatibility reasons. No reason for them to narrow their 9 and 10 speed chains internally if Shimano and Campy had not done so.

External pin widths are as follows:

11 speed Campy 5.5mm
10 speed 5.9mm
9 speed 6.6mm
8 speed 7.2mm

Everything I've read -- Sheldon Brown, Wikipedia, Wikibooks, other sites -- suggests that 3/32" is the standard internal width for nine-speed chains. I've seen some KMC chains advertised as being 11/128" internally. My current thinking is that KMC is "fudging" by 1/128 to save some weight. I could be wrong, but that's my current belief.

Thanks for posting this it's a good reference. I'd also like to add that pre-2006 campy 10 speed chain is 6.1mm and, yes, this stuff does make a difference.

That's correct. Also, Wipperamann's early Campy 10-speed chains (10X1, etc.) were 6.2 mm and Wippermann's early Shimano 10-speed chains (10S0, etc.) were 6.0 mm. Recently Wippermann has gone to 5.9 mm for all of their 10-speed chains.

Per a recent KMC download I did the Shimano 9 and 10 speed chains are 11/128" wide internally too.

I just measured the internal width (of the inside links) of both a Shimano 9-speed HG-93 and a Wippermann 10S0 10-speed chain and got 0.087"-0.088" for both. An 8-speed Shimano IG-90 measured 0.097". For reference, 11/128 = 0.086" and 3/32 = 0.094"

Not that it really matters but reducing the internal width while leaving the overall width the same would actually make the plates thicker, adding weight.

FWIW, the chainring tooth thickness has not been changed for a very long time. It should be the same on 8,9 and 10 speed rings and even most 7 speed.

The new Campy 11 speed chainring teeth are .1mm thinner than the 10 speed teeth. The distance between the inner plates of the chain is also slightly narrower, but it still works adequately with 10 speed rings.

Although all modern 10 speed chain are 5.9mm across the outer plates, they are not all the same across the inner plates. Campy and SRAM are about .1mm thinner and this affects the fit of master links is you don't use the proper model.

Be careful of accelerated wear on your chainrings if you use the wrong chain, one designed for more speeds than the the chainrings/cogs you are mounting it on.

Cog/Tooth Width (From Sheldon Brown)

• 8 Spd: 1.8mm
• 9 Spd: 1.78mm
• 10 Spd: 1.6mm

Chains from 7spd and 8 speed are the same. same spacing, same cogs. the rear cluster is just wider, and the wheel not as good structurally as a result. 8speed is popular out of china no-name factories and is junk that should be avoided.

Having tried to use quality SRAM chains I had, on clusters that are designed for less gears than the chain is designed to be paired with, I can attest that most of the time, the chain won't even go down onto the cogs and won't seat itself properly.

I recently did some work on an old 8 speed Gary Fisher mtb a friend bought for her son. I replaced the old chain with a 9 speed because that is what I had. It shifted well on the stand and also when I rode it around the block. Should I retrieve the bike and replace the chain with 8 speed?

don't be a sarcastic troll.

I have tried some SRAM chains, 9 speed, I think it was 951 and 971 if my memory is correct, on some freewheels not designed for 9spd, and the chain wouldn't go on.

your old gary fisher probably had the 8speed spacing, but thinner cogs, and a thinner steel chainring. are you still restoring old all-steel bikes with cotter-pin steel cranksets and steel brakes? or have you finally accepted that people should be riding on something lighter than 50lbs?

normally I would just ignore you, because you are making these otherwise nice forums very unpleasant for all of us, but I don't want you misleading people into doing stupid things. putting a thinner chain on a good bike, with components actually to spec, will accelerate wear on the alloy chainring's teeth, as the chain is narrower than the teeth are wide. some cogs might not accept the chain either, some might, some might difficultly and cause accelerated wear and weakening to the chain - not to the breaking point, but so as to increase chain stretch for serious riders. at the prices a chain go for these days, (and you can buy them in bulk - find out where bike messengers buy them in your city), it's really not a smart move to use the wrong chain on a quality drivetrain.

...as for your garyfisher and other antiques, well, you can probably use whatever.

hmmmm... have to say I have run 9 and 10 speed chains on an 8 speed set up and it shifted great and was quiet as a mouse, I suspect poor drive train maintenance accounts for more wear than running a thinner chain....each to his own I say..

8 speed spacing but thinner cogs and a thinner chainwheel? Thinner than what? What the heck does that mean? It's 8 speed. Nobody is trolling you, calm down. I would be interested to hear if others have experienced the problems you have. It's not nice or reasonable to bash old bikes. 8 speed works fine for lots of folks.

So is this the most irrelevant thread of the day winner ? Why are we splitting hairs here? If you have the wrong chain but it fits use it if it doesn't then order the correct one. Merry Christmas.

Why so hostile?

Perhaps the freewheels you used were 5 or 6-speed and the cogs were indeed too thick for a 9-speed chain. I currently have one bike with an 8-speed Shimano cassette and a 10-speed Shimano chain and it shifts flawlessly and runs very quietly. No problems with that combination.

Data point- Sachs changed their freewheel cog thicknesses from 2mm to 1.8mm (and thickened the spacers to retain the same 5mm cog to cog dimension) back at some time in the mid 1990s. Made for smoother chain run engaging their teeth. Also made for faster cog wear. Andy

Did anyone ever figure what this was all about? Was poster trying to put a 9 speed chain on a 5/6/7 FREEWHEEL? Weird that anyone would think it would work but who knows? I wouldn't want to be "misleading people into doing stupid things." So if anyone (who has a clue what they are talking about) can explain to me why I should not use a 9 speed chain on an 8 speed CASSETTE, I'm happy to learn.

This structural weakness goes for all the 8, 9, 10 and even more so for 11 speed.

However, using a MTB (wider) 135 mm wide hub with an 8-9-10 speed system provides very good structural strength. 7 speed is better though.


What 6 and 7 speed systems lack is the bearing strength, at least the freewheel ones. 8 speed is easily found in cassette/freehub combination (hard to find as a freehub), while 7 speed is hard to source as a cassette.

Most of this is incorrect.

First, when Shimano and others went from 6/7-speed to 8+ speed, the rear dropout spacing was widened from 126 to 130 mm so the extra wheel dishing was insignificant and wheel strength and durability did not suffer at all. Are you really aware of a huge increase in wheel failures since the change, which happened over 25 years ago?

Second, we still don't know which freewheels you tried to use that 9-speed chain on but I'm currently using a 10-speed chain (even narrower than 9-speed) on an 8-speed cassette and it works perfectly.

Sturmey Archer makes 3mm thick & 2mm thick cogs in the long standing 3 spline fitting.. 1/8 & 3/32.. FWIW.

but congratulations on Measuring things..

FROM LMP UK ON 16.11.25 HORRIFIC DEPRESSING WEATHER.
We are not bike engineers and am just writing to say cannot understand the chain width discussion which gives the fraction 1/128 which converts to .0859 or 2.183 width. I have never seen a chain that narrow on any bike. My opinion is it would be less confusing if we stuck to mm rather than fractions. Most folks will measure chains with ruler/mic/caliper. I dont think im stupid but some things in life baffle me.Maybe its the wheel tooth width. Am exhausted working 7 days a week 52 weeks a yr so not too intellectual. Thank you. Happy xmas.

Ten years since this thread last saw any activity, but I'll bite.
That's 11/128", being a 1/128" reduction from 12/128" aka 3/32". Chains have always been measured in fractional inches, 1/8" for single to 4 speed, then 3/32" for newer 4 speed to 8 speed (with 7 & 8 speed being narrower externally than 5 & 6 speed). Then 9/10/11/12/13 speed turned up and we should maybe be using thousandths of an inch now instead of fractional notation.

Maybe because it doesn't?
1/128" = .0078125" or .198mm

What job requires 7 days a week 52 weeks a year?!

AI.

Maybe it 'thinks' it's got a 'job' (because of its programming) but to me it's just doing what it was built and programmed to do: run constantly, using up electricity for little to no positive benefit to society.

I suspect LMP is an AI doing its thing, asking questions & making absurd statements to better 'learn' things.

It's clear enough (at least to me) that 1/128", in the discussion here, refers to a reduction in width of some chains vs. more traditional 3/32" (= 0.0938” or 12/128") type, not the actual width of these 'thinner' chains themselves.