chain length confusion

tsenior
tsenior Posts: 664
edited January 2011 in MTB workshop & tech
ok i replaced the big ring off my 2nd hand 2005 Marin Attack Trail with a bashgaurd last night and went to shorten the chain going from 44t to 34t i expected to have to remove 5 links.

having let all the air out of the shock and fully compressed the suspension at the most travel pivot position i measured the existing chain over the big rings: only 2 full inks spare :?

the only expanation i can come up with is the chain was too short to start with and thinking about it the guy i bought it off mentioned he had snapped the previous chain and replaced, he also admitted he was not that good at maintinance.

i've ridden it a bit but dont use the big ring much and avoid the combinations to be avoided so probably not stressed it too much.

any other damage that could be caused by having a too-short chain?

and going forward: big-big + 2 libnks at full travel sound ok?

Comments

  • tsenior
    tsenior Posts: 664
    ok proper (off)road test this weekend, hope the above is fine.......
  • 02gf74
    02gf74 Posts: 1,171
    chain round biggest front ring and biggest sprocket then add 2 links.

    note: the chain does not go through the rear derailleuer when doing this check.
  • 02gf74
    02gf74 Posts: 1,171
    chain round biggest front ring and biggest sprocket then add 2 links.

    note: the chain does not go through the rear derailleuer when doing this check.
  • BG2000
    BG2000 Posts: 517
    The method proposed by 02GF74 sounds valid, though I've never tried it.

    My method is to loop the chain through everything, put it in the smallest at front and back (you'll never use this gear ratio of course) and pull the chain ends together, until it starts pulling the rear derailleur forward, against its spring tension. The chain ends will be overlapping at this point, so you can work out how many links to remove.

    I'd say my method is more universal as it applies to all type of rear derailleur (remember, not all MTBs have long cage RDs).
  • cavegiant
    cavegiant Posts: 1,546
    02gf74's method s the normal one, it mentions it is every instruction book that coes with the chains!

    just try it on the stand, set it to the length that lets you access all the gears you want without removing your rear der.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • 02gf74
    02gf74 Posts: 1,171
    there is another method but I cannot recall exact details., something like chain on big ring and smallest sprocket on back BUT this time going through the rear derailluer, the length is adjusted so that the jockey wheels are in vertical alignment.
  • tsenior
    tsenior Posts: 664
    cheers guys, used 02GF74s method, only had to remove 1 full link, so chain must have been way to short for the previous set up with big ring.

    no wonder he snapped one.

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