Chain Length on new build

absv
absv Posts: 149
edited October 2012 in MTB workshop & tech
I'm in the middle of building an 09 Giant Trance from the frame up with 2013 SLX drivetrain. I have a GS Rear Mech, 11-36T cassette and 38/24 chainrings.

I used the largert cog/largest chainring plus 2 links method but now it all seems a bit tight when on the largest cog/chainring, does this look right:

Untitled.jpg

20120930_222139.jpg

I also noticed that the chain seems to bend as it comes off the largest cog, hopefully these pics will show what I mean:

20120930_213651.jpg

20120930_213618.jpg

As per the Park Tools website I have two spacers on the drive side of the bottom bracket (68mm shell) and none on the non-drive side but it looks like I could do with one less spacer?

Thanks,

Comments

  • nicklouse
    nicklouse Posts: 50,675
    so did you runs the suspension through its travel?

    and i see you did not rad the parktools webby correctly for a 68mm BB and no device you have 2 drive side and one non drive side. You are a spacer short.

    bbshell_1.jpg
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • absv
    absv Posts: 149
    Sorry my mistake, I have one on the drive side (just checked). I put weight on the bike when I measured the length but the rear mech looks a bit stretched to me?

    Thanks for the quick reply.
  • The Northern Monkey
    The Northern Monkey Posts: 19,174
    shouldn't use the big-big combo when riding anyway... but yeah, that looks short!
    Santa Cruz Butcher
  • nicklouse
    nicklouse Posts: 50,675
    absv wrote:
    Sorry my mistake, I have one on the drive side (just checked). I put weight on the bike when I measured the length but the rear mech looks a bit stretched to me?

    Thanks for the quick reply.
    so you are still wrong.

    chain will be fine then.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • absv
    absv Posts: 149
    The Northern Monkey wrote:
    shouldn't use the big-big combo when riding anyway... but yeah, that looks short!


    Forgot to say its 2x10 so thought big big would be ok? Any ideas what I did wrong, I put it on big/big without going through the rear derailuer, plus two links then I put the quick link in so thats three if I understand it correctly. I only took about 3 maybe 4 links out of the chain anyway.

    Nick: I meant one on non drive and two on drive as per park tools, at least I know what I meant :D as long as I won't damage the mech I'm happy to ride and see what happens if you think it's ok.
  • bikaholic
    bikaholic Posts: 350
    It's not verboten to use the extreme gear combinations - it's advisary to use them with caution as the chain is at max tension at one end and at max slack at the other.

    Forgot to ask:

    Does the chain drop down to a smaller cog when you pedal backwards?
  • nicklouse
    nicklouse Posts: 50,675
    absv wrote:
    Forgot to say its 2x10 so thought big big would be ok? Any ideas what I did wrong, I put it on big/big without going through the rear derailuer, plus two links then I put the quick link in so thats three if I understand it correctly. I only took about 3 maybe 4 links out of the chain anyway.
    before cutting the chain you should have then run the sus through the travel to check that it was not to short.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • absv
    absv Posts: 149
    nicklouse wrote:
    absv wrote:
    Forgot to say its 2x10 so thought big big would be ok? Any ideas what I did wrong, I put it on big/big without going through the rear derailuer, plus two links then I put the quick link in so thats three if I understand it correctly. I only took about 3 maybe 4 links out of the chain anyway.
    before cutting the chain you should have then run the sus through the travel to check that it was not to short.

    Sorry to come across as very dim but whats the best way to do this? If we ignore the suspension part of it for the moment, it looks quite tight to me just sat there not moving with no-one on it (as in the pic), as I used the big/big plus two links method shouldnt it be about right (at least while its just stood there with no-one on it)?

    As a test I put it on without removing any links 1st and it looked fine on big/big then when I dropped to small/small it was very saggy and touching the tyre:

    20120930_213119.jpg
  • felix.london
    felix.london Posts: 4,067
    If you're using a GS - I think you've got the wrong mech!

    I'm using a GS (XT M781) and the capacity is 35T - must be the same for the SLX, no?

    I am bang on the 35T limit with my 22/36 x 11-32 setup so you must be over that as you have larger rings everywhere!

    EDIT - with the setup you state you are on 39T
    "Why have that extra tooth if you're not using it?" - Brian Lopes

    Votec V.SX Enduro 'Alpine Thug' 2012/2013 build

    Trek Session 8
  • absv
    absv Posts: 149
    Cheers Felix, unfortunately it looks like you're right (on paper at least :( ) Any ideas whether it'll work or should I just get the proper length rear derailleur for the job?!

    Bugger..... :evil:
  • supersonic
    supersonic Posts: 82,708
    If you don't sue that gear combo, then no problem. Better to have the chain right for the big/big combo than the small/small, should you accidently hit the former.
    GT ZASKAR CARBON TEAM

    VOODOO CANZO

    Come and see me at https://www.facebook.com/biketyke/
  • felix.london
    felix.london Posts: 4,067
    absv wrote:
    Cheers Felix, unfortunately it looks like you're right (on paper at least :( ) Any ideas whether it'll work or should I just get the proper length rear derailleur for the job?!

    Bugger..... :evil:

    Yep - guess that's why it's so loose on the smaller rings...the cage is too short

    I could be interested in buying that mech off you :wink:

    Or change the cassette to a 11-32 which would bring you down to 35T but you could be struggling with a 24x32 lowest gear.
    "Why have that extra tooth if you're not using it?" - Brian Lopes

    Votec V.SX Enduro 'Alpine Thug' 2012/2013 build

    Trek Session 8
  • coblck
    coblck Posts: 217
    check park tool link below yer photo looks like the one thats ok in the park photo for big ring big ring combo

    http://www.parktool.com/blog/repair-hel ... gth-sizing

    but you've defo got the wrong rear mech like previous post change cassette or buy sgs one. Hope this helps.
    Giant tcr pro ultegra
    Cannondale CAADX GRX 812
    Voodoo Marasa 2011
  • felix.london
    felix.london Posts: 4,067
    Yeah - I forgot to add, your original photo looks fine to me. As long as the chain is making an 'S' shape through the mech and spinning both jockey wheels I'd say there wasn't a problem with chain length. And as stated a longer cage mech would get rid of that slack chain in the small-small combo.
    "Why have that extra tooth if you're not using it?" - Brian Lopes

    Votec V.SX Enduro 'Alpine Thug' 2012/2013 build

    Trek Session 8
  • absv
    absv Posts: 149
    Ive just got home after being away for a couple of days, Ive now taken a picture on small/small with the chain shortened. Can I ask just one more question and see if the pics below look OK?

    Big/Big:
    Untitled.jpg

    Small/Small:
    20121002_2102431.jpg

    Thanks for all of the help so far!
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Looks ok, I'd test the suspension growth though. Also looks like your rear gear cable loop into the mech could be about halved
  • coblck
    coblck Posts: 217
    Looks bang on my spesh fsr xc looks the same 2x10 setup and same 120mm rear travel and the suspension growth pn chain is minimal, you should have no problem.
    Giant tcr pro ultegra
    Cannondale CAADX GRX 812
    Voodoo Marasa 2011
  • absv
    absv Posts: 149
    Chunkers1980 wrote:
    Looks ok, I'd test the suspension growth though. Also looks like your rear gear cable loop into the mech could be about halved

    The gear cable are only temporary fitted as I need some more ferrules for the outers, must admit I wasn't quite sure how long/short to go though.

    Thanks for all the help! Looks like it may work :)

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