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Chainring Removal Help

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  • 26-05-2008 7:21pm
    #1
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭


    Ok I'm in the middle of a ss/fix conversion project with an old racer. I'm trying to keep the budget as low as possible, so I'm going to try and stick with the stock crankset which has got two chain-rings, a 52 and a 40.

    I'd like to remove the 40 and just stick with the 52, but the problem is they seem to be pinned together (I don't know what the correct term is).
    pic1
    pic2 (It's filthy, I know:o)

    Is there a special tool to remove these, or do I just have to go at it with a hacksaw?


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    #2
    erizo
    Closed Accounts Posts: 99 ✭✭erizo


    Maybe a picture from the other side may help. They usually have a kind of screw in one of the sides as my experience with old bikes, so it may be removable if it is shimano or campagnolo stuff.


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    #3
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    The fasteners look the exact same on the other side, there's no screw or anything.


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    #4
    erizo
    Closed Accounts Posts: 99 ✭✭erizo


    I have no clue then. maybe any of the other guys could have some similar experience.
    Is it very old?


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    #5
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    It's off a Dawes bike from the 80s, and I'm assuming it's an original part, although I'm not sure.


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    #6
    flickerx
    Registered Users Posts: 1,234 ✭✭✭flickerx


    Sean_K wrote: »
    Is there a special tool to remove these, or do I just have to go at it with a hacksaw?

    Standard 5mm allen key turned anticlockwise in the centre of the bolts should do it no?


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    #7
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    flickerx wrote: »
    Standard 5mm allen key turned anticlockwise in the centre of the bolts should do it no?

    There ain't no bolts:p


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    #8
    uberwolf
    Registered Users Posts: 7,580 ✭✭✭uberwolf


    is there any prospect that there is a circular pin like device keeping them in place?

    And are you sure they can't be levered (popped) out?

    this discussion on chainwheel replacement (navigate on the left) shows how it should be done!
    http://www.utahmountainbiking.com/fix/ were they the new type


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    #9
    kona
    Registered Users Posts: 7,525 ✭✭✭kona


    clean it up first for gods sake then you can see exactley what its like!!!:D

    id say they will come off, they head for the bolt may be on the inside of the round bit.

    if all else fails, grind the ends off and it should slip off.


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    #10
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    uberwolf wrote: »
    is there any prospect that there is a circular pin like device keeping them in place?
    Pretty certain yea. They look like they were put in as cylinders and then the ends were flanged outwards and rounded.
    uberwolf wrote: »
    And are you sure they can't be levered (popped) out?
    Yup, there's nowhere to get any purchase.

    Here's a couple of pics from the other side:
    pic3
    pic4
    It's smooth all the way through and there's a good bit of wiggle room for a 5mm allen key.


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    #11
    kona
    Registered Users Posts: 7,525 ✭✭✭kona


    flathead screwdriver, hammer.

    place the screwdriver on the little gap bit on the cylinder, tap it in a circle till it comes out happy days:D


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    #12
    erizo
    Closed Accounts Posts: 99 ✭✭erizo


    as for the impression i get from the picture, the big chain ring is holding the small one, so i would just grind the ends.


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    #13
    blorg
    Registered Users Posts: 15,989 ✭✭✭✭blorg


    They look like some sort of rivet to me, but I can assure you I am not in any way mechanical, what would I know!


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    #14
    Morgan
    Registered Users Posts: 2,481 ✭✭✭Morgan


    It looks as though the chainrings are riveted onto the crankset. On a lot of cheap chainsets the rings aren't replacable. You might need to get a different crank

    OR if you can bash the rings off the current one it MAY have a standard BCD (bolt circle diameter) to which you could attach a single ring (you can measure this)

    OR you could just use it with two chainirngs - won't really make much difference (other than aesthetic).


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    #15
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    I think i'll give the brute force method a try and cut out the rivets,

    Thanks all for the help:)


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    #16
    flickerx
    Registered Users Posts: 1,234 ✭✭✭flickerx


    Morgan wrote: »
    OR you could just use it with two chainirngs - won't really make much difference (other than aesthetic).

    Amen to that. Just leave it as it is. Function over glamour. You could make a mess of a decent enough crank. Clean it up a bit and it'll look alright.


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    #17
    erizo
    Closed Accounts Posts: 99 ✭✭erizo


    Let us know how does it look like when you finish your project!!
    good luck


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    #18
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    erizo wrote: »
    Let us know how does it look like when you finish your project!!
    good luck

    Will do yea, it'll be a couple of weeks until I can get cash together for a new set of wheels etc, but as soon as I do I'll get some pics.

    I went ahead with a hacksaw, and it came off grand, just took ages:rolleyes:


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    #19
    flickerx
    Registered Users Posts: 1,234 ✭✭✭flickerx


    Damn it! I have the same problem now on the fixie I'm putting together at the moment. Its more or less the exact same as yours Sean_K.

    I dont think the crank will come off the bottom bracket (its old and rusted looking in there, I'm scared to go at it with the tools), but the chainline from the sprocket runs straight to the inner chainring, not the outer one, and when the crank is turning there's a very slight movement of the chain against the back of the larger chainring. Its nothing major but I'd still like to make it as quiet as possible. Dont know if its possible though!

    Might give yanking out the crank a go...


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    #20
    Morgan
    Registered Users Posts: 2,481 ✭✭✭Morgan


    If you're feeling creative/destructive you could cut off the outer chainwheel (just outside the rivets, leaving them intact) - wouldn't look too bad if you take some time to do it neatly / file / clean up afterwards.


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    #21
    Thomas_S_Hunterson
    Closed Accounts Posts: 6,151 ✭✭✭Thomas_S_Hunterson


    flickerx wrote: »
    Damn it! I have the same problem now on the fixie I'm putting together at the moment. Its more or less the exact same as yours Sean_K.

    I dont think the crank will come off the bottom bracket (its old and rusted looking in there, I'm scared to go at it with the tools), but the chainline from the sprocket runs straight to the inner chainring, not the outer one, and when the crank is turning there's a very slight movement of the chain against the back of the larger chainring. Its nothing major but I'd still like to make it as quiet as possible. Dont know if its possible though!

    Might give yanking out the crank a go...


    You probably need to get a crank extractor to get the cranks off the BB, it's a special tool to prise the cranks off. Otherwise i'd say it's next to impossible.

    See here: http://www.chainreactioncycles.com/Models.aspx?ModelID=4939
    Morgan wrote:
    If you're feeling creative/destructive you could cut off the outer chainwheel (just outside the rivets, leaving them intact) - wouldn't look too bad if you take some time to do it neatly / file / clean up afterwards.
    If his crankset is the same as mine, then only the outer chainring will be attached to the crank if you know what I mean. The inner/smaller one is only attached by the rivets to the outer chainring.


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    #22
    flickerx
    Registered Users Posts: 1,234 ✭✭✭flickerx


    Sean_K wrote: »
    You probably need to get a crank extractor to get the cranks off the BB, it's a special tool to prise the cranks off. Otherwise i'd say it's next to impossible.

    Yeah I got one of them but they're still not great. The last time I tried it, the threads on the crank got churned into dust - no taking the crank off.

    Got another bike from a neighbour last night, had been sitting in his garden for months if not years... the cranks will definitely have to come off this one, the b/b is in a bad way and has to come out too.


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