Compatibility of combined chains
 

So I just installed a new 11-34 range cassette on my tourer, and the additional teeth required that I add two links to my chain. I had run out of links on the chain I was running, but I did have another chain lying around. The original chain is a Shimano HG-93, and the two fill-in links are SRAM PG-950.

The SRAM links are both being held to the Shimano chain with Shimano HG-93 pins, which from what I can tell have a slight lip to them. Also, both connections to the Shimano chain have Shimano outer plates and SRAM inners. Other than aesthetically I haven't noticed any rough spots in my pedal stroke from the change.

I've done this type of lashing-together-chains thing before, but only with two SRAM chains (970 and 950). The way I'm figuring it, since the HG-93 pins are holding together the outer plates on both connections I should be okay, but I just wanted the pick the collective brains of BF to see if anyone had done this (or something like this) before. I'd much rather do this than pay another $20-30 for two more links.

Thanks.

I guess your going to find out but I'm not to optomistic about the outcome.

Hm, it's all just rollers and plates right? At least that's what I'd like to think. It sounds like you already went ahead and did it - did it work ok? Shifting and so forth unaffected? It doesn't sound like a terrible idea, but I also thought that mixing cassette sprockets was going to be ok. It was ok, but shifting wasn't quite as smooth.

Yeah, I did it the other day. There were some problems originally because I had an SRAM pin holding together Shimano outer plates (that link would start to disconnect after about a mile), but once I switched it out for a Shimano pin everything's been fine. For now, that is. But shifting-wise I haven't noticed a difference, no.

Given that folks have been using Sram connectors on Shimano chains forever and not reporting problems I can't see where you'd have any.

I'm assuming the both the chain and spliced links are new. Also it sounds like both ends of your added section are inner links so both Shimano pins are going into a Shimano plates made for them. The only issue might be a slightly different sound as the splice moves through is the shape of the links is different enough, but it wouldn't matter mechanically, so use the dough you saved to buy a few beers to celebrate your success.

Awesome! Thanks!

Yes, the spliced links are new, and the chain is only about 2 weeks old. Glad to hear this is a common solution, always nice to know.

One reason this is not a good idea is each brand differs in the roller OD and ID. A Campy chain, for example, may measure .200 inch between the rollers and a Shimano may measure a substantially larger .210. The reason is that the OD is smaller and the ID is larger.

Unless you're using a proruding pin chain, a SRAM chain requires a master link to join it.

I'm sure you can buy a few links of compatible Shimano chain from your LBS. In the end, I think this will be the lowest cost solution that I would have confidence in. I'm a big fan of SRAM chains but not as a "patch" to a Shimano. I think I would rather spend a little more and have confidence that I won't have to fix this on the side of the road at some point.

This would be the ideal solution, but the LBS in town is run by one of the most underhanded businessmen on the planet, and so I'd rather not contribute to his business in any way, regardless of how little the cost of those links would be. The next time I visit my preferred LBS, which is about 60 miles away, ^this^ is probably what I'll do; but until then, I'm happy to report there have been no issues as of yet.

As far of the standard goes, the pitch and roller dimension is standard. but the width come in various sizes and also the pins are out of the standard, so each manufacturer have their own pins with their dimensions on it (it's not a surprise that sram pins match shimano)
I prefer YBN chains - very strong made from a manufacturer that is doing lots of types of chains from bicycle to industrial heavy duty applications.

Roller diameter is NOT standard (OD or ID).

outer diameter of the roller is standard: http://en.wikipedia.org/wiki/Roller_chain

If you would bother to check the rollers with calipers, you would find the rollers do vary between brands. The .500 inch pitch must be held to a very tight tolerance, but the .306 inch nominal roller OD, the ID and the diameter of the bushing it rolls around (formed into the inner side plates) all vary from one brand to another.

A simple check of the space between the rollers with internal caliper tips will show a Campy chain to measure about .200 inch and other brands like Shimano and KMC to measure at least .210 inch. That is a substantial difference. That difference is also why a lot of chain wear tools will show a Shimano or KMC chain to be worn by .25% when they are new, while a Campy chain shows no wear. The tool is producing a false reading since all of the chains will have the same .500 pitch (when new), it's the difference in roller spacing that the tool is reporting as "wear". As the chain wears, this flaw in the design gets even worse. The wear on two rollers can be as large as the wear on all the pin/bushings included in the length measurement, causing the tool to report more than twice the actual elongation.

A Campy roller will measure about .304 inch, when new, but a KMC might only measure .301 inch (neither is .306). That only accounts for .006 inch of the .010 inch difference in roller spacing. The rest comes from the roller ID and bushing OD.

maybe the chainrings-cogs-chains are on another standard for Campagnolo. For the rest usually it's OD is 7.77mm - that is standard, the chainrings and cogs engage on the roller, if it was not standard then the chainrings would have slight differences. The internal diameter and pins is not standard as I stated before.
These knowledge does not come from wikipedia or the web, it's found in books, in ISO standards (and other standard, by no mistake ISO, ANSI, GOST, DIN and JIS standards for chains are exactly the same. They are made so to fit chains/bolts/nuts and other small assembly components cross-standards, some of the standards were majority in some days and that hold till present an other standards align to this common standard, some difference still exists in other domains)

Did you select your forum name before or after you cobbled together this chain?:D

I worked in the machining industry for most of my 32 year working career, so I don't need a lecture on dimensions, tolerance or standards.

Campy does not use a different standard than the rest of the brands. You can use any brand of 10 speed chain with Campy cogs or a Campy 10 chain with any other brand of cogs and it will work just fine.

Every dimension has a tolerance. None of the brands makes their rollers .306 inch in diameter because that is the maximum diameter. Shimano and KMC are always smaller than Campy. Campy, SRAM and Wipperman make their rollers closer to the maximum at .304 inch.

I'm just stating the easily proven fact that there are differences in the roller OD and ID between the brands, even though they are made to the same standard.

It would seem that the roller OD and the distance between rollers is dictated by the properties of the chainrings and cogs. That is, these all together comprise a particular "system". Things that are compatible with a particular Shimano (for example) system would have the same pertinent dimensions. Of course, there are no requirements that non-pertinent dimension (eg, pin size) have to be the same.

also the OD of the roller is measured as it is not within two or more rollers, the distance between two rollers (not their center, but the outer dimension) is dictated by the play between ID and pin, and by the wear of the pins. The standard is a standard, it has tolerances (written in the standards), we both do know a bit of something and it's clear to me what a chain dimensions are as probably you know it as well, I'm an automotive engineer and work at renault designing gearboxes, I have the standards on my desk, I'll have a look through them.
How close shimano gets to the standard is another thing, (and the tolerance is specifide in the standard, if it fits within it it's ok, if it doesn't, than those chains should be discarded from factory. Same thing for machining cog, sprokets, chainrings, screws, nut, bolts, bearings, etc. They could do some sorting after ID and pin size and ID of plates so that they match perfectly, but that's just too much to ask, I'd be glad they fall into the standard dimensions and not outside of it. (and the standard means pitch, outer diameter of roller)
Just measured a roller of my YABAN chain: 7.775mm (with a micrometer) spot on, those 0.005mm can be the oil on the roller and is well within the tolerance.

I guess you're missing the point that although each brand follows the same standard, the rollers are not guaranteed to have the same nominal OD or ID. Of course the roller spacing changes with wear, but I'm talking about brand new chains. Campy chains will have a smaller space between the rollers, due to more material on the OD and ID, than Shimano or KMC. All of the rollers on a given chain will have very small deviations from a nominal diameter, but not all brands use the same nominal OD or ID. I don't know why the manufacturers choose a nominal OD of .304 over .302, but they do and it's very consistent.

You will not measure one roller to be .304 and another only .301 on the same chain. If you mix brands, that's what you could get.