Thursday, January 10, 2008

Proper chain length

I have come across a lot of discussions about chain length and I have seen some very complicated calculations on how to get the proper length. There are a few things to consider as in; chain growth due to suspension type, the length of your chain stay, what size sprockets and cluster you are running, and if you are running the standard three ring, dual ring or single ring front setup. There is no way to just say, the chain should be this long, you have to install it on the bike and follow a few basic steps. For us this basic set up seems to work every time. Install the chain on your largest front sprocket and on the largest rear sprocket. In this case it is a dual ring set up. (1) With the rear derailleur in the lowest gear or climbing gear position, and the front derailleur set for the big ring (in this case the 34 tooth middle ring) thread the chain over the front sprocket, rear cluster and through the rear derailleur as normal, also if you have a roller system, make sure to run the chain over the roller. Bring the two ends of the chain together and connect them with a master link (We are using the SRAM Power link) or just hold the chain in the appropriate place. Now look at your rear derailleur cage. (2) (3) The derailleur cage should be between lets say the 5 o’clock to 6 o’clock position. Our preference is 5 o’clock, in the 6 o’clock position or vertical, the chain will have too much slack when in the small to small gear configuration. This set up should give you plenty of slack to compensate for chain growth as the bike goes through its travel. For a more advance set up look at last picture. (4) In this picture you can see that the derailleur cage is in the 4 o’clock position, this is very tight, but we tested to insure the chain will not bind. The way we tested it was to remove the shock and put the chain stay/swing arm through its full travel making sure the chain never overly stress the derailleur. Sense this frame has very little chain growth we are able to get away with such a tight chain. This is not recommended unless you are very familiar with setting up bikes, and sure that the chain will not bind, plus it does add a little more stress to the drive train. With that said, it is great for controlling the chain. I hope this helps.
Hope this helps


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