Replacing drive set.

Hi again,
So my specialized rock hopper 2021 has a 30 tooth chain ring the stout peddle set iv heard it may help me to swap up to a 32 tooth chain ring but my chain ring is a connected item to the drive pedal so i,m looking into possibly upgrading the bottom bracket and getting a peddle set that i can add a 32 tooth chain ring onto so i can bolt it on rather than as is now its fitted to the peddle does anyone know what i,m looking into as in what bottom bearing and a decent but not over the top peddle set reason for this is its also going to be used for commuting to work as well so I feel I would gain by having the 32 tooth chain ring on it gear and speed wise when its being used on the road ???


  • JBA
    JBA Posts: 2,852
    That would be so much easier to read if you added some punctuation!

    I believe the Stout chain set has a direct mount chain ring so you should be able to change it for a larger one.
    If you remove the chain set (self-extracting bolt - look it up) you should see that the chain ring is held on by a screw-in collar similar to a cassette lock ring.
    I don't know what the availability of replacement chain rings is though. Stout is Specialized's house brand so you'll have to do a bit of research to find out what make of chain rings can be fitted.

    “Life has been unfaithful
    And it all promised so so much”

    Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Toughtroad SLR 1 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 2009
  • Hi thanks for the reply but as feared the chain ring on this bike is fixed to the drive pedal no way of removal :(

  • Ncovidius
    Ncovidius Posts: 229
    edited September 2021

    Hi thanks for the reply but as feared the chain ring on this bike is fixed to the drive pedal no way of removal :(

    That looks a lot like a removable collar in the shot ( although admittedly I’m not familiar with those chainsets ) It looks like it will come off with a standard threaded BB cup / centre lock brake rotor removal tool. I’m happy to be corrected if I’m wrong though.

  • reaperactual
    reaperactual Posts: 1,185
    edited September 2021
    Looks suspiciously like a 3 piece square taper crankset, looking at the hole obviously.

    Does the non drive side crank come off with a centre crank bolt the same way?

    It does still look like the chainring is direct mount and replaceable but as mentioned it's a unique/unusual Specialized crankset.

    On the other hand you can see it properly so you could be right and that specific chainring isn't replaceable. 🤔
  • yes both come off with a centre bolt and crank puller tool and its deffo not removable ive even found a thread where another guy was asking the same thing and he contacted specialized and they confirmed it is non removable.
    The thread also stated that a Shimano XT BB-MT800 - HollowTech II Bottom Bracket - Threaded 68/73mm may be a upgrade to a bb for this frame and then I may have more options for a different crankset meaning I could also then fit a removable chain ring hopefully thoughts please ???
  • reaperactual
    reaperactual Posts: 1,185
    edited September 2021
    Seems like you have a standard BSA/ English threaded 68 or 73mm wide bottom bracket shell, (likely a 73mm).

    Any BSA threaded bb will be fine and works for both shell widths depending on bb spacer configuration.

    If you decide on Shimano Hollowtech II specifically then there a couple of bb's to choose from.

    Quite a few Shimano HT2 1x mtb cranksets available and also a few copy brands that use the same Hollowtech system. Either with replaceable direct mount or spider mounted chainrings in various sizes to choose from.

    You can go with a bigger chainring and only limited by clearance from the chainring teeth and chainstay.
  • mully79
    mully79 Posts: 904
    edited September 2021
    Note changing from a 30T to a 32T chainring will gain you approximately 1mph if you're using the smallest rear sprocket which is about 20mph on a 650b at 90 cadence.

    If you're fit enough to average 20mph on a rockhopper commuting then i'd be impressed.
  • In general on my other 2 bikes I use a 32 tooth front chain ring so i,m used to what power I can put to it in a situation i,m just fnding i,m struggling with this 30 tooth chain ring especially on long rides can really tell that im peddling a whole lot more.
  • Hi ive found a frew possibilities now but thing im not sure about is they state chainline sizes and ive no idea what mine is ???
  • mully79
    mully79 Posts: 904
    In the case of a single ring its the distance between the centre of the frame (seat tube) and the teeth of the chainring.
  • So do I measure from centre of seat tube to inner or outer of chain ???
  • mully79
    mully79 Posts: 904
    centre of seat tube to middle of chain ie the teeth of the chain ring
  • So crank set I was hoping to get the shimano DEORE M5100-1are impossible to get in this country atm im assuming due to covid. Ive now seen the RACE FACE AEFFECT 24MM MTB CRANK ARMS - BLACK which is the correct spindle width for the bb I mentioned earlier but it says spindle length is 137mm now ive no idea what length the spindle needs to be for my bike once i fit the new bb any ideas please ???

  • All done now really straight forward and a nice low price upgrade that I can deffo feel the benefit of.
  • One last question im going to buy a 34 tooth as well now im assuming if i put the 34 tooth on im at the point then where I would need to have another chain with more links in it ???
  • If you are still using the original chain that you used on the original 30t chainring then it would be a good idea to fit and size a new chain.

    Worth buying not just for getting the length right but also to avoid any wear on the new chainring if the chain is well used and stretched a little.

    Be careful with choosing a new 34t if you buy a non Shimano brand. Your new cranks and many Shimano cranksets have an assymetric bolt pattern and need a matching bolt pattern on any replacement chainring.