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Mech hanger snapping issues....

welshkevwelshkev Posts: 9,690
edited February 2013 in MTB workshop & tech
Hi Guys,

I've snapped 2 mech hangers in a week and 3 in the last 6 months. This last time i was literally just pedalling up the road 2km into a ride. After I snapped the one 2 weeks ago I had a new chain put on there by the LBS, along with new cables and the gears were indexed.

I've checked that the hanger isn't working loose at the bolt where it attaches to the frame, it doesn't over shift causing the chain to get stuck, the drop outs look straight and square.

I'm at a total loss as to why they keep breaking...any ideas?

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    pics of the set up?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,804
    Chain too short and dragging rear mech into cassette? (you'll see some marks on the rear mech on the tab round the top jockey wheel - don't ask how I know this....I JUST DO!)
    They normally bend first, pics of a snapped one to give an indication of the direction it's being bent in?
    Do you recall what gear you were in (or changing into)? Front and rear.....
    Severe chainsuck dragging the mech forward? (possibly into the cassette as well)
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    ok, i'll get some pics when i get home close up.

    chain is the right length - checked by the lbs last week as i asked if it was too short, i was in the granny ring front and the big ring back as i was peddalling up a pretty steep hill and i'd stopped to answer the phone, that's how i remember which gear lol.

    this what i'm running: p4pb8217315.jpg

    and after it snapped: 19416_408497205896066_1634165855_n.jpg
  • Is the mech bent? After snapping that many hangers it could be your problem
  • welshkevwelshkev Posts: 9,690
    Is the mech bent? After snapping that many hangers it could be your problem

    it doesn't seem to be, but yeah i'll take a good look at it later and take some pics
  • The RookieThe Rookie Posts: 27,804
    Can you get a pic with the gears in big big please, and a close up of the broken ends 9as many as you can) to try and judge direction of bend/type of failure. Close ups of chainring

    Granny front though suggests it's not a chain length issue UNLESS for some reason it climbed onto the big ring at the front....
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    yeah i'll get some pics later.

    no it definately didn't jump up the rings on the front. it was nice smooth pedalling and then ...snap..off it came.

    the mech going into the cogs does sound like an option though. it's not going into the wheel as i've checked all the spokes for damage etc :?
  • nicklousenicklouse Posts: 50,675 Lives Here
    what mech is it? with clutch?

    what frame?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • welshkevwelshkev Posts: 9,690
    nicklouse wrote:
    what mech is it? with clutch?

    what frame?

    2011 (i think) SLX 10 speed. no clutch and it's on a cove stiffee fr
  • nicklousenicklouse Posts: 50,675 Lives Here
    Mmm ok then see if you can get some clear pics of the break surface. and the top and bottom edges of the hanger where the break happened.

    focus is more important than size. ;)

    this the one you are using

    prod_18656.jpg
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • welshkevwelshkev Posts: 9,690
    yes nick, that's the type of mech hanger it is, it doesn't say cove on it though, i bought it from crc.

    i've taken some pics, but i'm not sure how much use they'll be as my camera didn't want to focus properly in the dark last night!

    p3pb9103357.jpg

    p4pb9103353.jpg

    p4pb9103355.jpg
  • The RookieThe Rookie Posts: 27,804
    Take it into the Kitchen - it's compulsary!
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    OK, sorry guys i've been really busy and haven't had time to take pics.

    but i fitted the new mech hanger last night and tested it. it seems that the mech just siezes and just extends as the wheel spins and doesn't feed the chain through, this is causing the chain to just wrap around the cassette and pull off the hanger. someone suggested new jockey wheels as they could be seizing?

    does that make sense? :?
  • nicklousenicklouse Posts: 50,675 Lives Here
    again pics on what happens with the mech (video is also accepted ;) )

    remove chain and spin the jockey wheels and also rotate by hand and see what you can feel.

    and check for stiff links.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • welshkevwelshkev Posts: 9,690
    bloody hell, so demanding!! :wink:

    ok, i'll get it done :)
  • The RookieThe Rookie Posts: 27,804
    I very much doubt the jockeys are seizing......
    even if they did the chain wouldn't wrap round the cassette it should still be being pulled towards the chainwheel surely? The chainwheel would be feeding chain off the bottom and too the rear mech...

    Any chance bad chain suck is pulling the mech forward as the chain sticks on the chainwheel? Sounds much more likely!
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • nicklousenicklouse Posts: 50,675 Lives Here
    welshkev wrote:
    bloody hell, so demanding!! :wink:

    ok, i'll get it done :)
    or you could fly me over to you?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • welshkevwelshkev Posts: 9,690
    Right I've found the problem now I've actually had chance to look at it in the light. There's a splayed chain link and when it gets to that point it pushes it to the side of the jockey wheel and causes the chain to get stuck. Thus causing the mech to extend as the chain is jammed.

    Take out said link and put a power link in?
  • nicklousenicklouse Posts: 50,675 Lives Here
    it is a solution.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,804
    Check chain stretch and maybe replace......
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    Check chain stretch and maybe replace......

    it's a brand new chain - 1 ride old
  • The RookieThe Rookie Posts: 27,804
    So nothing to do with the first hanger failure?
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    So nothing to do with the first hanger failure?

    no, the first time i'm pretty sure a rock hit it as i heard a twang like a rock did.

    BUT: i've got everything back together now and when shifting through some gears the chain will still foul on the mech. the mech does look like the long bit (cage?) is slightly out of true. it's an old mech that's had plenty of abuse so i've ordered a new one and hopefully this will solve the problems.

    fingers crossed. i've never noticed it fouling on the mech before so maybe i bent it this last time? :?
  • The RookieThe Rookie Posts: 27,804
    Chain routed correctly past the tab, not the (common) wrong way?
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • welshkevwelshkev Posts: 9,690
    new mech on and everything seems to be running sweet.

    the gears aren't indexed properly yet, but it'll go from the big coog to about the 5th with no fouling of the chain or mech. fingers crossed that was the issue.

    cheers for your patience guys :D
  • konadawgkonadawg Posts: 447
    Minor note, if in the pic of the bike you are in big-big as looks like, the chain seems to be too long, the RD would ordinarily be outstretched forwards in that gear combo.

    If that is so, when you are small small the RD would be rubbing against the cassette and the chain would flop.
    Giant Reign X1
  • welshkevwelshkev Posts: 9,690
    konadawg wrote:
    Minor note, if in the pic of the bike you are in big-big as looks like, the chain seems to be too long, the RD would ordinarily be outstretched forwards in that gear combo.

    If that is so, when you are small small the RD would be rubbing against the cassette and the chain would flop.

    since that pic mate i've had a new cassette and chain put on by the lbs, so it's not really relevant now.

    cheers anyway, as you can probably tell i'm mechanically useless :lol:
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