Help wanted to find new middle chainring, 32T 104BCD

peter.cheyne
peter.cheyne Posts: 45
in Workshop
My mtb needs a new middle chainring. The LBS guy said he didn't have one to fit. The size is 32T 104BCD. I was about to buy one on Amazon when I realized many on there are of the 'narrow wide' kind'. I had to search online to see what that was, realizing they don't work with derailleurs.

I wrongly assumed any 32T 104BCD would do. Is there anything else I need be aware of? Here is the maker's pamphlet on my chainrings:

https://si.shimano.com/pdfs/ev/EV-FC-M340-2189.pdf

I need part number 6, the middle ring. Can't be found now, as it's pretty old.

Comments

  • reaperactual
    reaperactual Posts: 1,185
    edited July 2020
    A whole new square taper crankset will only cost around £30 if you shop around. This one is on sale for under £20:-

    https://www.deporvillage.net/shimano-altus-8v-cranks-175-42-32-22-cuad-black?gclid=EAIaIQobChMIz9S4g6XC6gIVcWHmCh3O4wfbEAQYDCABEgIxF_D_BwE

    Not top of the range but good, strong and will last.
  • peter.cheyne
    peter.cheyne Posts: 45
    edited July 2020
    Cheers, Reaper,

    I'm in Japan. Would this one do? By which I mean, would it fit and perform fairly comparably?

    The reason I thought I should simply get the needed middle chainring is because I can fit that without removing the crankset. I don't have a crank puller (admittedly, they are not so costly), but nor do I have a ratchet set for removing the crank bolt.

    I think I'm still just going to look for a middle chain ring and try to be sure it's not the 'narrow wide' type.




  • reaperactual
    reaperactual Posts: 1,185
    edited July 2020
    Yeah, the one linked would be fine and comparable. Any square taper crankset will do with same chainring sizes for a straight swap.

    Only other thing to be aware of if slightly different tooth count is and obvious change in ratio and possibly a small height adjustment and fine tune to front derailleur to shift at optimum performance.


    I paid around £5 for a cheap crank puller not the best quality but fine for occasional use. Same applies for a socket set which is worth the investment in the long term for future jobs.

    Not so easy to find a middle chainring replacement for triple cranksets because it's pretty cheap to buy a full new crankset.

    Your right to avoid narrow wide as they are for 1x drivetrains and made for chain retention and not viable for multiple ring cranksets.
  • david37
    david37 Posts: 1,313
    reaperactual said:

    A whole new square taper crankset will only cost around £30 if you shop around. This one is on sale for under £20:-

    https://www.deporvillage.net/shimano-altus-8v-cranks-175-42-32-22-cuad-black?gclid=EAIaIQobChMIz9S4g6XC6gIVcWHmCh3O4wfbEAQYDCABEgIxF_D_BwE

    Not top of the range but good, strong and will last.

    Dont buy that, I think it needs a 122.5 mm spindle in order to clear the shell. (unless thats whats in their already). If I'm wrong fair enough but its worth checking first.

  • reaperactual
    reaperactual Posts: 1,185
    edited July 2020
    david37 said:

    reaperactual said:

    A whole new square taper crankset will only cost around £30 if you shop around. This one is on sale for under £20:-

    https://www.deporvillage.net/shimano-altus-8v-cranks-175-42-32-22-cuad-black?gclid=EAIaIQobChMIz9S4g6XC6gIVcWHmCh3O4wfbEAQYDCABEgIxF_D_BwE

    Not top of the range but good, strong and will last.

    Dont buy that, I think it needs a 122.5 mm spindle in order to clear the shell. (unless thats whats in their already). If I'm wrong fair enough but its worth checking first.

    EDIT: Not quite Pal.
    The spindle length can be variable and is dictated by frame design but any Shimano replacement triple crankset will fit to your square taper regardless of its spindle length.👍
  • peter.cheyne
    peter.cheyne Posts: 45
    These things are easy to get wrong, or what's a bike maintenance forum for?
  • reaperactual
    reaperactual Posts: 1,185
    edited July 2020
    peter.cheyne said:

    These things are easy to get wrong, or what's a bike maintenance forum for?

    Agreed, the more input the better, gives a more informed answer.

    Only did a quick search for replacement middle rings, can't seem to find any maybe you will find one? Good luck Peter.Cheyne
  • peter.cheyne
    peter.cheyne Posts: 45
    edited July 2020
    Thanks, Oxoman!

    No rush, as today I just replaced the BB in my road bike, my favourite cycle. Lately, I had to leave a wide space between the chain and the front derailleur as the axle was wobbling (chainrings, cranks, and all). Now fixed and feels beautiful!

    I'll ask at Spa Cycles for the MTB middle chainring.

    Cheers!

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