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Should a Cassette/Freehub 'just come off'?

peatpeat Posts: 1,243
edited October 2014 in Workshop
Quick question,

Once the rear wheel is removed from the bike, should the Cassette & Freehub just be able to be pulled off in one go? I was investigating an annoying rattle a while back, had removed the wheel and was tapping in against the ground (at an angle, cassette side down) when the cassette and freehub (held together by outer retaining cap) simply parted company with the hub and fell on the floor.

I thought nothing of it at the time and just popped it back on, but I just watched a 'replace you freehub' video on YT and it showed the guy having to use a large hex key to unfasten the freehub from within the axle/hub.

The wheel/hub is Bontrager Race Lite, Shimano cassette. I can't offer much more on the spec right now.

So, have I missed a trick here and am i riding an accident waiting to happen?

Posts

  • Escher303Escher303 Posts: 342
    Are you saying you hadn't undone the cassette lock ring and the cassette was being held on by either the skewer or the rear dropouts? So you did nothing other than remove the rear wheel from the bike? The cassette is supposed to be held on by a lock ring that can only be removed by a splined cassette removal tool and they're normally on pretty tight. The cassette should absolutely not fall off. Has someone recently changed the cassette and forgotten to do up the lock ring?

    Have you got one of these next to the smallest sprocket on the cassette? http://www.chainreactioncycles.com/camp ... lsrc=aw.ds

    (That's a campag lock ring, but the shimano one looks similar)
  • jimothy78jimothy78 Posts: 1,407
    Escher303 wrote:
    The cassette is supposed to be held on by a lock ring that can only be removed by a splined cassette removal tool and they're normally on pretty tight. The cassette should absolutely not fall off. Has someone recently changed the cassette and forgotten to do up the lock ring?

    Escher, you haven't read the post properly - the lockring was in place, but the freehub came off, taking the cassette and lockring with it.

    Peat - how the freehub body is held on to the hub shell depends entirely on the hub. Some manufacturers (like shimano) use a threaded bolt to hold it on, which is indeed operated by a large (10mm, usually) Hex key. Other manufacturers, like Hope, rely on seals and friction to hold things together (when the wheel is out of the frame) but when in the frame the pressure on the endcaps stops anything from working loose.

    Check the manufacturer's information for the exact hub you have, to find out if anything's missing. If it's not, then it may be that one (or more) of the seals has worn, so there's not enough friction to hold things in place when the wheel comes out - this is what happens with the hope hubs mentioned above if the main freehub seal is worn.
  • peatpeat Posts: 1,243
    Just to confirm, Escher, yes, the lock ring is very much in place. The whole lot just slides off. It's literally the scewer tension keeping everything in place when fully assembled.

    These are they: http://cdn4.coresites.mpora.com/rcuk/wp ... G_4467.jpg

    It sounds like it could be a hope-style arrangement in there then. (It certainly sounds like a hope when freewheeling... ;) ) They are sealed cartridge bearings, definitely no room to stick a 10mm hex down there.

    In which case, it may need some attention. Certainly, replacing the freehub is on my list as last time i had the cassette off, i could see it had worn into the freehub splines by a mm or so on some sprockets.

    Cheers
  • My Specialized Roval Rapide 35 wheels have this freehub/cassette slide off system, I hadn't come across it before having had Mavic wheels for years but its quite handy when you want to clean the cassette and lube the pawls etc and not had any problems with it so far.
  • PokerfacePokerface Posts: 8,640
    edited October 2014
    I've had freehub assemblies come off the way you describe before. Off the top of my head I can't remember which wheels it was on but no, it's not an accident waiting to happen.

    Generally the skewer/frame, etc holds everything tight in place when riding so no danger of it falling apart.

    With most wheels the freehub is held on the way you describe - you need a hex key to get it off. On some wheels it slides off. I recall opening my bike box after travel one time, finding the freehub and gears separate from the wheel and thinking it was broken. It wasn't.

    I'm sure someone else will post to assure you and give you a fix if there is one, but basic answer I have is: s'all good.
  • peatpeat Posts: 1,243
    goody goody.

    Cheers all.
  • g00seg00se Posts: 2,218
    Just more circumstantial stuff, but my Hope freehub can be pulled off. But it needs a fair bit of effort.

    First, the axle end cap needs to be pulled off - holding in a vice or pliers gives enough grip to do this.

    Then the freehub can be pulled off by hand (still a fair bit of effort).

    I suppose you could pull the two off together with the cassette and lockring installed but it'll be a fair old yank. So if yours is similar, it'll be worth checking the seals etc to see if they have perished and allow the unit to release will little effort.
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