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Retro Grouch
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2,091 Posts
Discussion Starter · #1 · (Edited)
I put this together years ago, but I've tried to keep it current; it should answer a few questions.

Traditionally single speeders used 1/8 inch BMX chains, since most single speed (SS) bikes are just 26" wheel BMX bikes anyway. Other reasons include the fact that SS track bikes and old BMX bikes had 1/8 inch cogs and chainrings and since 1/8 inch chains looked bigger than 3/32 chains they must be stronger. Also 3/32 (7-11 speed) multi-speed rated (MSR) chains are designed to derail, something you don't want to happen on a SS bike. A second look however shows there had been a lot more R&D money thrown at MSR 3/32 chains by Shimano and SRAM, so most 3/32 chains meet or exceed the tensile or "pull" strength of 1/8 inch chains. Since most single speed components available today come in 3/32, it seems logical to use 3/32 chains. On the other hand, while some claim that 1/8 inch chains on 3/32 gears cause more noise and wear than 3/32 chains, the jury is still out on this matter as many more use prefer this set-up. In the real world, it would seem the use of 1/8 inch chains work fine on 3/32 components and some, such as the SRAM PC-7 and KMC Kool chains are stronger.

Prior to about 20 years ago, pretty much all chains had a bushing construction, meaning the two inner side plates are held together by tubular bushings. This construction worked very well until the need for thinner and stronger chains led the industry toward bushingless chains. That is not to say that bushing style chains are weaker, bushing style chain continue to be the strongest chains available (NJS used for Keirin racing), they are simply more expensive to make and more difficult to maintain. Also, as bushing style chains wear, they loose their lateral rigidly and shift poorly, which is less of an issue with single speed and track racers. Wipperman makes their Connex bushing chain which has a somewhat cult following. They are high quality chains and many swear by them. One of the more popular 1/8" chain these days is the KMC D101 SL; a relatively lightweight bushing style chain available in gold. Further, there are also stainless steel chains. These are great chains for adverse weather, but a stainless steel chain is weaker than a standard steel chain, so should consider a real need for stainless steel, as they tend to wear faster.

One issue that comes up from time to time is the use of 1/2 links. The use of a ½ link allows you to vary the chain length by 1/2 inch intervals, rather than one inch with a standard link. This comes in handy when you are trying to convert a bicycle with vertical dropouts. 1/2 links are very plentiful these days but sometimes can be difficult to match particular pin widths and can make for a weaker link then the rest of the chain.

So do you need a single speed (non MSR) over a MSR chain? No, not really. Is there any advantage to a 1/8 inch chain? Yes, there can be if you have chainline and/or derailing problems a SS chain can help; and as I said before some are stronger. However if you are using a tensioner such as the early Surly Singleator a 1/8 chain may not work. Additionally if your are having a problem with your Singleator skipping, they work best with a 3/32 " chain, in the push-up mode, without a 1/2 link, and with the addition of a zip-tie connecting the Singleator arm to the chainstay.

The tensile strength of a SRAM PC-7 is about 2500 ft lbs and only come in 1/8 inch (and pimp gold like the KMC D101 SL; the D101 is rated at a minimum 2200 ft lbs); all other MSR SRAM chains (including the PC-58) are around 2023 ft lbs. The KMC Kool chains rate at 2860 ft lbs (the "SL" drops down to about 2500 ft lbs) and comes in both 3/32 and 1/8 inch. The KMC Z chains (with an H in the model number) also come in both sizes (i.e. the 3/32 Z610H; my choice of chain), rate at 2640 ft lbs and are a bit lighter than the Kool chains. The Z410 (no "H") is KMC's basic 1/8" chain and the one that comes in all the colors; it is rated at about 2000 ft lbs. Finally KMC ranks most if their MSR chains at 2314 ft LBS; I have not seen any published data for Shimano chains, but I would assume they are consistent with SRAM MSR chains..

So what chain should you buy? There is a plethora of 1/8 inch chains out there; one of the favorites is the SRAM PC-7 (on the other hand there has been considerable anecdotal information that the SRAM PC-1 (1/8) chain is of low grade and should be avoided).
KMC also makes a line of 1/8 inch (or 3/16 inch if you dare) and 3/32 SS chains. They come in various weights and strengths so you pay your money and make your choice. As far as MSR 3/32 chains go SRAM PC-58 seem to be popular with the anti-Shimano crowd as are the KMC chains. Shimano wise any of the better HG or IG chains will work.

As a final caveat there is the question of longevity aka "streaching". Regardless of what you hear, all chains get longer with use (I'd call that stretching). There are so many factors that go into this "lengthening", that it's futile to try and rank one chain over another. Just try and keep your chain clean and lubricated and before it has stretched 1/8" over a foot, replace it.

Also checkout http://www.sheldonbrown.com/rinard/chain_stiffness.htm and http://www.63xc.com/gregg/gregchai.htm for some good chain spew.
 

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Retro Grouch
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2,091 Posts
Discussion Starter · #3 ·
Cunha said:
So you wrote the shelton brown chain info post? Its a good piece whoever wrote it.
That would be a no good buddy. Yes, there is information from many for sources in the piece, it's called research. When you spend most of your life investigating and documenting the results, writing a little piece like this is pretty simple. I include the Sheldon Brown site as it goes into greater detail about lateral chain stiffness. It's actually almost irrelevant to this FAQ, but I thought it was interesting.
 

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Ovaries on the Outside
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4,424 Posts
Holy shitballs! Great work wasted on the mindless interwebz.

Your write up would make a great sticky. Maybe it even should be, but I've never seen evidence that most asking the question have the reading comprehension to make it through all of the paragraphs, let alone go to the work of trying to find the answers before asking questions.

Great work though, and it adds to the pile of evidence going to show that you are smarter than the average sser.
 

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Out spokin'
In cog? Neato!
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16,322 Posts
Golly gee whiz Brad, ya wrote a novel. I didn't read it cuz I've already found a chain I like but thanks for making mtbr's SS forum better for everybody by giving regulars a link to refer non-searchers to.

--sParty
 

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Damn Fool
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123 Posts
Thanks for the post! Now I don't have to be one of those annoying people who asks questions that have already been answered.
 

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openwound
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580 Posts
aka brad said:
"Use whatever chain you want; the odds are it won't make any difference." Hows that?
I like. (not to say that what you'd written was not informative, because it is.

I'd add: Dropping big coin on a chain is just dumb. They're wear items. Buy the cheap one that you like and just plan to replace it regularly.
 
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