Thursday, December 13, 2012

A crowd-sourced chain testing procedure: Campa C9 vs. SRAM PC-971

Measuring arrangement: Chain is hung up on nail, pulled down by a 1000g weight. Measuring 6 full links on the inside with calipers
Changing a worn chain is a task you regularly encounter if you ride a decent amount of miles. How often you have to exchange them depends on a whole number of factors--gear ratio and cross-chaining, weather conditions, lubrication and cleaning, riding style and--the make and model of your chain. For the past couple of years I have been riding mostly SRAM's PC-971 chain. It was the one recommended and sold cheaply by my LBS and its price to value ratio seemed to be in a good zone. Its more expensive brother, the PC-991 appeared to offer mainly weight savings; and the cheaper model PC-951, which I tried once, lacked the nickel-plating that prevents the chain from getting permanently rusty in the salty winters of Upstate New York and Quebec.
My previous go-to chain: SRAM PC-971

I never kept exact records of chain life but after some years I got the impression that other people's chains lasted longer. As I've said above, this can be due to all kinds of factors but in the German a consensus developed that the Campagnolo Record C9 in general seems to last longer than other chains.

The reference chain: Campa Record C9
Some evidence for this was produced in a chain test by forum member JensD, and I was excited when another member announced that he would start a crowd-sourced follow up test. Because of the number of factors affecting chain wear you have to keep as many of them as constant as possible. One way of doing this is to test the chain in a controlled environment. Tests of this kind are regularly done by various bike magazines but the problem is that the performance in a test stand doesn't necessarily translate into real-world performance. In order to address this, BaB suggested the following procedure: Take two half-chains, join them together with master links, and then ride them on the same bike until one of them has passed the wear limit. At the beginning and at the end of the test the chains should be accurately measured while off the bike by hanging them on a nail, weighing them down with a 1 kg weight and then taking multiple measurement of 6 full links with calipers.

Reference weight: a water-fille SIGG bottle
There are a few potential problems with this procedure: some have pointed out that the differences in wear in the two parts of the chain will also lead to a specific wear in the cassette cogs which in turn will affect chain wear. And similarly, some believe that master links tend to wear faster than regular chain links. No matter if this is the case or not, it should not be a problem for the test results: the different amount of wear between the two chain parts will still be indicative of one chain's relative superiority over the other.

My current chain was already stretched beyond the recommended point for replacement and therefore I kept riding it until the bitter end before switching out the complete drivetrain. This delayed my testing for a bit but as of yesterday I'm in, comparing a Sram PC-971 with the Campa C9! Others on have already started the test and I am very curious about the forthcoming results. I will post here regularly about on-going developments. If anyone else is interested in participating, please let me know.

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