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I'm replacing chains on a number of bicycles, and trying to decide what chains to purchase. I'm a fan of Sram's master links, so I'm comparing the Sram PC-971 to the PC-991. The PC-991 is considerably more expensive, but it seems like the lighter weight chain would make a significant difference in pedaling performance, because of the angular momentum involved. Are my instincts correct, or is this just a sales gimmick on Sram's part?

Also, I've seen some reviews indicating that the hollow-link chains are prone to breakage -- is this something I should be concerned about?

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how does Shimano's 9 speed chains compare with PC-951? If I have anything to believe to Wiggle's reviews, PC 951 has a head over the S, not sure though comments? –  user652 Feb 11 '11 at 21:31
    
Well, shimano chains don't have a master link, so if you want to take it off, you've got to use a chain tool. I've been told that every time you use a chain tool, you increase the risk of failure. Between that and the convenience of sram's master links, I've come to prefer sram chains. –  Benson Feb 11 '11 at 23:09
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2 Answers

up vote 7 down vote accepted

I'm no racer so I'm probably speaking from a very different point of view than you were interested in. I have used Sram 9-speed chains for years on my touring/commuting bicycles. I have used the 971, 981, and 991 and haven't been able to see any difference in performance or longevity, either. With my wet-weather commuting here in the Seattle area where it's pretty nearly wet every day from October through March, and then there's plenty of rain in April and May, too, I have been able to wear out chains and cassettes very quickly.

I'm not a mountain biker--or at least not an avid one--so I have never really hammered the chains in the muck but I have never had one of their chains break. I've just managed to wear them out over time.

I do greatly appreciate the master link because it makes it easy to take the chain off the bike and put it back on again. Before I switched to a bike with a Rohloff internally geared hub for my commuting, I would keep two chains in rotation on my bike and take one off, soak it in cleaner, and let it dry while I put the other clean chain on my bike.

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Thank you, the fact that you've used all three models and haven't been able to tell the difference means a lot. I'm a mountain biker and have done a little road racing, but not a lot. I've done a fair bit of touring lately, too. Based on your advice, and advice from folks on twitter, I'm inclined to go with the 971, since it's so inexpensive. :-) –  Benson Feb 7 '11 at 20:27
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I've not done the maths, but angular momentum is proportional to the radius of the circle. So those big wheels benefit a lot from mass reduction, but the relatively small turn around your chainring much less so.

Overall I'd think that the chain mass can largely be considered just another part - if it's much cheaper per gram to save weight there than your saddle or bars go for it, otherwise your money may be better spent elsewhere, especially as the chain is a consumable part.

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