Crank/Drivetrain Is this normal ??

dots_unirea
dots_unirea Posts: 18
edited June 2013 in MTB workshop & tech
Hi all,

I recently bought a stumpy expert and the cranks are somehow loud when rocking crank arms back and forth. The bottom bracket is alright, no play whatsoever in the bearings. The only thing I could imagine is that the rear derailleur is not holding enough tension (very very slack chain on smallest cog/smallest front wheel)


http://www.youtube.com/watch?v=Iqe9IoJGGxs

Comments

  • warpcow
    warpcow Posts: 1,448
    Sounds normal to me (though can't really tell the volume). Hub sounds tend to reverberate through the rest of the wheel, which makes them sound louder.
    Commie Meta SL
    Evil Sovereign
    Santa Cruz Heckler (gone)
    On One Inbred (gone)
    Ragley Mmmbop (gone)
  • freshe
    freshe Posts: 63
    I think this sound is common for all parked bicycles. If you thake your rear wheel out and turn the cassette back and then forth it will make exactly the same sound. There is nothing strange here imo.
  • felix.london
    felix.london Posts: 4,067
    dots_unirea wrote:
    (very very slack chain on smallest cog/smallest front wheel)

    That doesn't sound good. Are you sure your chain is correct length and/or you have the correct size rear mech for your setup?
    "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
  • rubbernekker
    rubbernekker Posts: 112
    dots_unirea wrote:(very very slack chain on smallest cog/smallest front wheel)



    That doesn't sound good. Are you sure your chain is correct length and/or you have the correct size rear mech for your setup?

    Lots of full suspension bikes require chain lengths that are too long in the small small combination, in fact almost all Specialized 2x10 FS bikes are baggy in this combination. It is indicative of nothing awry.
  • dots_unirea
    dots_unirea Posts: 18
    Thank you all for your input.

    I went to Halfords the other day and I could replicate the same sound on all the bikes displayed on the shopping floor (all hardtails)

    The chain length is spot on, I measured it 10 times :D . The bike components are stock, rear derailleur is an SRAM X0 middle cage. I also read that a full suspension requires slightly bigger chain due to rear triangle moving away from BB when fully compressed.

    I'm just wondering if your bikes are doing the same sound ....

    Cheers
  • The Rookie
    The Rookie Posts: 27,812
    dots_unirea wrote:
    The chain length is spot on, I measured it 10 times
    OK, but how did you measure it if you then ask this?
    dots_unirea wrote:
    I also read that a full suspension requires slightly bigger chain due to rear triangle moving away from BB when fully compressed.

    All on parktools website on how to actually 'measure' it.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

Categories