Converting to a single chain ring

Johnny_Cage
Johnny_Cage Posts: 57
edited June 2014 in MTB workshop & tech
Hi guys, first post, I am excited :o

Didn't know whether to put this in buying advice or workshop, it will probably be a bit of both :mrgreen:

Basically, I am looking to convert my bike to a single chain ring.

Unfortunately my chain rings are riveted together, so I can't seperate them - so I guess I have to upgrade my crankset?
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Comments

  • Chunkers1980
    Chunkers1980 Posts: 8,035
    No, you just need to change your crankset to one that can take just a single ring (workshop answer)
  • Johnny_Cage
    Johnny_Cage Posts: 57
    edited May 2014
    So I am basically looking to get a new crankset that has the rings bolted together, instead of riveted together?

    I see that they come in different speeds, 9sp, 10sp, 11sp. Why is this?

    Does it need to correspond with the speed of your cassette?
  • bailsofhay
    bailsofhay Posts: 191
    or get some used arms and a new ring of your preference.
    What speed is your current setup?
  • Johnny_Cage
    Johnny_Cage Posts: 57
    3x8
  • bailsofhay
    bailsofhay Posts: 191
    Chain and cassette should match up i.e. 8spd cassette with 8spd chain but you should be alright with a 9spd crankset/ ring/s up front.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    OK, cool.

    So should I opt for a Shimano crankset, since that's what my cassette is, or does it not matter?

    I am looking to use the middle ring, will all 9sp rings be the same size?
  • bailsofhay
    bailsofhay Posts: 191
    Brand shouldn't matter
    Chainrings have various teeth counts, 36 tooth rings seem popular with single ring setups but it is down to preference. Less teeth = better climbing but less power on flats
  • cooldad
    cooldad Posts: 32,599
    Makes no difference as long as you are changing the BB.

    But if you're not you'll need a crankset that gives the right chainline with your current BB.

    And no, rings differ in size (number of teeth) and fitment. But you would most likely get rings with a crankset.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Johnny_Cage
    Johnny_Cage Posts: 57
    I admit to not knowing what a bottom bracket was until now (still don't) :lol:

    I am reading the guide on this site:

    6. Fit to the inside of the tabs

    To get the optimum chainline, you need to fit the single ring to the middle ring position (on the inside edge of the chainring tabs). Make sure you clean these tabs thoroughly. Over time they can become pretty manky and any build up of dirt can affect the way the ring attaches and impede a good tight, even fit.
    http://www.bikeradar.com/gear/article/workshop-how-to-convert-your-mountain-bike-to-1x9-or-2x9-gearing-29342/

    I am trying to make sense of it. I think I need a crankset where the bolts also go through the middle ring (doesn't always seem to be the case) and I take off the big ring, and fix the crank arm directly to the middle ring. Is this correct?
  • benpinnick
    benpinnick Posts: 4,148
    You take all the rings off, and put the new single ring in the place where your middle ring was before.
    A Flock of Birds
    + some other bikes.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    benpinnick wrote:
    You take all the rings off, and put the new single ring in the place where your middle ring was before.

    I see, thanks.
    cooldad wrote:
    Makes no difference as long as you are changing the BB.

    But if you're not you'll need a crankset that gives the right chainline with your current BB.

    So, should I give it a shot with my existing BB, then if it isn't right, go ahead and buy a new one?

    No idea if it will be compatible.
  • The Rookie
    The Rookie Posts: 27,812
    Let us know what the 'it' you intend to try is and we'll give you a yes/no/maybe on whether it will work with you existing BB.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    The Rookie wrote:
    Let us know what the 'it' you intend to try is and we'll give you a yes/no/maybe on whether it will work with you existing BB.

    I'm looking to fit a 'Blackspire Super Pro Middle Ramped' chainring, on a 'Shimano Acera M361 Chainset Square Taper' crankset.

    Whether that will work with my existing BB, and also whether the chainline with this set up will run in the same line as it does now (with chain in middle ring)
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    What are you looking to gain out of this? As, as it stands all I can see is you losing money and range of gears for a little extra weight.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    I pranged the big ring a while ago, so it is un-usable and I have been running in the middle ring almost exclusively for months - and the times I have shifted down into the granny ring weren't essential.

    So I am interested in turning it into a single-ring bad ass setup.

    Aesthetics mainly :wink:
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Johnny_Cage wrote:
    single-ring bad ass setup.

    Makes me laugh that a lot!

    Your bike will not be bad ass
  • Johnny_Cage
    Johnny_Cage Posts: 57
    But the setup will be.

    What's your problem?
  • The Rookie
    The Rookie Posts: 27,812
    Just get on eBay and get some square taper cranks, can be picked up for less than a tender, superstar rings are a lot cheaper than the one you propose.

    What chain retention do you plan to use?
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    Planning on a chain guide of some description.
  • The Rookie
    The Rookie Posts: 27,812
    That's an aspiration, not a plan!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    Rubez? Is that you Rubez?
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Johnny_Cage
    Johnny_Cage Posts: 57
    What?

    So what's this business with the BB?

    Do I need a specific bottom bracket to run a single (middle) ring?
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    No, you need a certain chainline. Can be bodged by not just the bb axel length but running the ring inboard and outboard if possible. Have a read of Parktools
  • Johnny_Cage
    Johnny_Cage Posts: 57
    OK I am reading various guides, will check that one too, thanks.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    So on reading Parktools and other various guides (2 from this site) there seems to be not much (if any) mention about the chainline with regards to a single ring conversion.

    So, I'm guessing it isn't something that will present a problem as long as the ring sits in between anywhere where the triple ring worked fine?

    Though I am wanting the single ring to sit where the middle ring sits now, how is this achieved? A bigger BB to push the single ring out more? A spacer?
  • The Rookie
    The Rookie Posts: 27,812
    Yes you want the single to sit where your middle ring does now, so if you get a crankset designed for the same BB width and mount the single ring in the middle position, hey presto, job done. However different cranksets require different BB widths for the right chainline, so you may need to consult the makers technical documents to see what you have now and compare to that you intend to buy.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Johnny_Cage
    Johnny_Cage Posts: 57
    I am looking at a Deore crankset - so could it be as simple as buying a Deore BB?
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Exactly what Deore crankset - there are many. Part number....
  • Johnny_Cage
    Johnny_Cage Posts: 57
    OK so the guy at Chain Reaction got back to me, here is what he said...

    I can confirm that the Shimano Acera M361 Triple Chainset Square Taper will be fine with the Blackspire chainring and a bash. You will need a square taper bottom bracket for this chainset and I have given you a link below;

    http://www.chainreactioncycles.com/s?q= ... dimid=2219

    You just have to measure the bottom bracket width, and the bottom bracket spindle length to ensure that you get the correct bottom bracket.

    So, I need to get my old BB out and measure it?
  • bailsofhay
    bailsofhay Posts: 191
    I thought you were talking about a deore? Do you have the M361 at the moment?
    Current model numbers and details of proposed ones may help.

    Have you read this?
    http://sheldonbrown.com/bbsize.html

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