Removing Chainrings

Yacoby
Yacoby Posts: 211
edited April 2012 in The workshop
Hi

I need to replace my middle chainring, but it does seem quite as easy as I expected.

This is what they look like: https://www.dropbox.com/gallery/2667750 ... s?h=784d94 (Apologies for the phone photos, if you want ones at a different angle let me know)

It seems that the bolts are riveted on? When I try and unscrew them they just rotate. Also the middle ring doesn't look like I expect it to, as it goes all the way through and seems attached to the crankarm. In which case I assume I need some tool other than an allen key to remove the crankarm?

In other words, what is the best way to replace the middle ring? (And make it replaceable with more ease in the future?) Is it worth buying a whole new crankset that actually works like I expect it to?

Comments

  • rolf_f
    rolf_f Posts: 16,015
    If they were rivetted, they wouldn't have allen key heads now would they? :wink:

    The nut is rotating as it has a round sleeve and you've let everything get horribly gunked up! You'll need a little tool for it - I think they are just called a chainring bolt tool - less than a fiver.

    The one that goes into the crankarm should just unbolt with the allen key irrc.

    However, your chainrings look to be in a bit of a state (grime wise)and maybe more firmly stuck to the spider than the tool can deal with so don't be surprised if you need to go to the LBS anyway.

    Grease the bolts when you put them back and it's probably a good idea to free them on occasion to stop thing getting too siezed.
    Faster than a tent.......
  • Yacoby
    Yacoby Posts: 211
    Rolf F wrote:
    If they were rivetted, they wouldn't have allen key heads now would they? :wink:
    True
    The nut is rotating as it has a round sleeve and you've let everything get horribly gunked up! You'll need a little tool for it - I think they are just called a chainring bolt tool - less than a fiver.

    The one that goes into the crankarm should just unbolt with the allen key irr
    Ok, that makes sense.
    Rolf F wrote:
    However, your chainrings look to be in a bit of a state (grime wise)and maybe more firmly stuck to the spider than the tool can deal with so don't be surprised if you need to go to the LBS anyway.
    Ok. It is pretty grimy as I used it for mountain biking at one point.


    Also, thanks for mentioning the word spider. It allowed me to do some googling and now understand more how it works. In that case my follow up question is: The crank arm seems attached to the middle and outer chainrings rather than having a separate spider (or having the spider as part of the crank arms). The chainrings from places like CRC don't have this "feature" and I would assume that if I replaced the middle (which is what I am trying to do) and only used the outer as the spider would weaken it?
  • rolf_f
    rolf_f Posts: 16,015
    I've had a look at my bike which has a similar though not identical crankset. As far as I can see, there are just four bolts none of which goes into the crank arm. The chainrings will be pretty standard.

    Incidentally, how much are you planning on paying for the middle ring? And what condition are the other rings?

    I hate suggesting this sort of thing but you may find it makes more financial sense to replace the whole thing - eg with this crankset for £45 - http://www.merlincycles.co.uk/Bike+Shop ... sets+-+MTB
    Faster than a tent.......
  • Yacoby
    Yacoby Posts: 211
    Given the state of a few of the other rings and the fact that I am not totally convinced that the chainrings are removable (googling seems to indicate they aren't, although that might be old information) a new crankset might make be a good call. Although I would probably go for the cheaper Alivio (FC-M410) one from Rose. I assume from googling that it would be compatible (The BB I have is a Truvativ square taper).
  • centimani
    centimani Posts: 467
    I don't think they are removable, it looks like a throw away item once any part of it is worn.
  • Mad_Malx
    Mad_Malx Posts: 5,002
    Some of the teeth on the big ring look worn to me. I really don't think it worth buying just a middle chainring.
    Any square taper should be ok, as long as the inner ring is similar size - if inner ring is bigger might catch on the chainstay.
    However you may be on a slippery slope here - if your chainrings look like this I dread to think of the state of your bottom bracket.
  • Yacoby
    Yacoby Posts: 211
    Mad_Malx wrote:
    Any square taper should be ok, as long as the inner ring is similar size - if inner ring is bigger might catch on the chainstay.
    :D cheers.
    Mad_Malx wrote:
    However you may be on a slippery slope here - if your chainrings look like this I dread to think of the state of your bottom bracket.
    The BB probably isn't great, but it still works (I think) and doesn't seem to have any play. This bike is very much a ride till a part totally dies and then replace it with the cheapest possible part (that is worth the money).
  • rolf_f
    rolf_f Posts: 16,015
    Yacoby wrote:
    Given the state of a few of the other rings and the fact that I am not totally convinced that the chainrings are removable (googling seems to indicate they aren't, although that might be old information) a new crankset might make be a good call. Although I would probably go for the cheaper Alivio (FC-M410) one from Rose. I assume from googling that it would be compatible (The BB I have is a Truvativ square taper).

    I think you are right - thankfully my crankset is a lot more different to yours than I originally thought! The BB on mine was terrible and I replaced it with a Hope one. Now I'm going to source a Shimano replacement.

    Note - a new crankset usually comes with a bottom bracket.
    Faster than a tent.......
  • desweller
    desweller Posts: 5,175
    Rolf F wrote:
    Note - a new crankset usually comes with a bottom bracket.

    It doesn't if it's square taper.

    Further; if you're replacing the whole chainset, you will need to verify that the axle length and taper are correct on your old bottom bracket; if they're not then you'll get the wrong chainline.
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  • Yacoby
    Yacoby Posts: 211
    edited April 2012
    Deleted (Moved to a new topic)
  • rolf_f
    rolf_f Posts: 16,015
    DesWeller wrote:
    Rolf F wrote:
    Note - a new crankset usually comes with a bottom bracket.

    It doesn't if it's square taper.

    D'uh! Of course you are right - I should know; the last crankset I bought was square taper and the bb was extra! :lol:
    Faster than a tent.......

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