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  1. #1
    Join Date
    Sep 2007
    Posts
    2,516

    1x chain length calculation

    Over the winter I decided to upgrade from 1x10 to 1x11. As part of the upgrade I went from a cassette with a 46t large cog to a cassette with a 50t large cog.

    I know how to measure the correct number of links with a chain in hand, but is there any way to calculate links needed for the new cassette? Chain length on the 11-46t drivetrain was 113 links. Is it as simple as adding the additional 4 teeth to make it 117 links?

    Thanks in advance.

    Seth

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  2. #2
    Join Date
    Dec 2011
    Posts
    4,941
    If it's on the same bike and nothing else has changed (ie. you're using the same derailleur), then just add 4 links, but it also depends on how tight you were running the setup in terms of b tension and the old chain.

    The 50 cog will likely require different b tension in your rear derailleur, so I'd add 6 links and know that you're good to go. If the chain starts flopping and banging, then remove the extra.

    Edit to add: I'm tired and not explaining this very well.
    Quote Originally Posted by XXX-er View Post
    the situation strikes me as WAY too much drama at this point

  3. #3
    Join Date
    Mar 2010
    Posts
    505
    closer to half the cog is engaged with the chain, so you need to add half the # of links as added teeth, roughly...
    i would still check length at bottom out, but this method has always worked for me when the original chain was setup correctly and i was adjusting gear ratios

  4. #4
    Join Date
    Oct 2008
    Location
    Vernon BC
    Posts
    1,675
    I have never actually counted the links in a chain, despite wrenching on bikes for 2 decades... donít over think the maths.
    "Its not the arrow, its the Indian" - M.Pinto

  5. #5
    Join Date
    Mar 2008
    Location
    northern BC
    Posts
    17,987
    put the chain on the largest chain wheel which is easy on a 1x and largest sprocket, add 2 links so you only have to count up to 2
    I have a finishing nail in a stud where I hang the old chain, hang the new chain and just make them equal, so I don
    't count any links

    google gives you all kinds of hits on calculating chain length BTW
    Last edited by XXX-er; 03-25-2019 at 11:35 AM.
    Lee Lau - xxx-er is the laziest Asian canuck I know

  6. #6
    Join Date
    Aug 2008
    Location
    Central VT
    Posts
    4,028
    Quote Originally Posted by XXX-er View Post
    put the chain on the largest chain wheel which is easy on a 1x and largest sprocket, add 2 links so you only have to count up to 2
    I was always taught to measure a chain like this if you didn't have an old one to measure against.

    As said, be sure to measure you chain with your rear shocked fully compressed (easiest to take all the air our first.) Many suspension designs lengthen the chain when squished, which will lead to a snapped hangar if not measured right.

  7. #7
    Join Date
    Sep 2007
    Posts
    2,516
    Same bike, same derailleur, same chainring. Measuring the chain length and removing links with chain in hand has never been a problem.

    Yesterday was my first time counting links also, but here's why - some wrote on this site that the XTR chains are worth the upgrade (some getting 2-3x the miles on this chain with similar stretch) and I thought I'd give one a shot. I found an XTR 11-speed chain on pinkbike for cheap (PSA: if you can use 110 links or less, there's a chain on there for $20), but the number of links was borderline. I counted my chain links (113) and then realized that the PB chain wouldn't work. However, if I order a chain (XTR or other) that they come in 114, 116 or 118 lengths. That got me wondering which one I needed. I have never ordered a chain by number of links before, but realized that with my setup, this could bite me if I ended up with a 114 link chain. Hence. . . the question.

    Thanks for the info above - It sounds like 116 links is probably safe, but if I can find the 118, probably worth having a few extra links just in case.

    Seth

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