Is my freehub borked?

msw
msw Posts: 313
edited June 2010 in Workshop
I've been hunting down an odd niggly jump (feels like chain skipping) for a while now, and just to see if anything was there I took off and cleaned the rear cassette (Dura-Ace 7800 I think, 2008/2009 model anyway). First of all it wouldn't come off, but a screwdriver did the trick - at which point I found that the 3rd, 4th and 5th sprockets had each cut a little groove into the freehub body, which is why it wouldn't lift off easily.

Reading up on it it seems that this is sometimes a problem on cassettes with (comparatively soft) aluminium bodies. Seems like it might make sense to make the body of oh, I don't know, SOMETHING HARDER, but anyway, can anyone advise me?

1) how serious is this? I can't see it being a problem until their little grooves get deep enough that the sprockets are wrongly aligned for shifting
2) is there anything I can do to stop it getting worse?

(EDIT: I'm assuming it's not the source of my "jumping" problem, since that happens intermittently even without shifting, not just when I shift on to one of those cogs)
"We're not holding up traffic. We are traffic."

Comments

  • sungod
    sungod Posts: 16,522
    might mean the cassette wasn't tight enough, wouldn't have thought it will be a problem, i don't think you can do much beyond making sure it's tightened to the correct torque when you put it back (torque is often stated on the locking ring)

    for the jumping chain, things to check...

    is the mech hanger bent, or loose (take the rear wheel off, as sometimes the qr presses on the hanger so it feels secure when it isn't really)

    is the cable correctly routed and the housing free of gunk

    have you adjusted the rear mech as in shimano's instructions? they are here...

    http://techdocs.shimano.com

    are there any stiff links in the chain

    might due to chain/cassette wear, measure the chain to see how worn it is - if it's too far gone, then when you finally do change it you'll need to replace cassette+chain at the same time
    my bike - faster than god's and twice as shiny
  • John.T
    John.T Posts: 3,698
    This wear happens with all alu freehubs. Tightening the lockring will make no difference. Just live with it. Cheaper (heavier) ones are made of steel and do not do this.
    My Fleet.
  • msw
    msw Posts: 313
    Thanks both. John, any idea why it might happen on those 3 cogs and not others? I guess they're the ones that get most use.
    "We're not holding up traffic. We are traffic."
  • John.T
    John.T Posts: 3,698
    Those cogs have the smallest contact area on the freehub and the most use. Being larger than the smallest they also have more leverage thus more pressure on the conntact points.
    As for the jumping I can only suggest the usual. Sticky cables, indexing and chain / cog wear.
    My Fleet.
  • bexley5200
    bexley5200 Posts: 692
    borked ?
    going downhill slowly
  • msw
    msw Posts: 313
    bexley5200 wrote:
    borked ?

    Borked. http://www.urbandictionary.com/define.php?term=borked
    "We're not holding up traffic. We are traffic."
  • bexley5200
    bexley5200 Posts: 692
    its fuc*ed you mean,boll*cked
    going downhill slowly

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