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  1. #1
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    Replacement BB for 2012 specialized rockhopper comp29

    I am sorry I have to make a post asking this but,does anyone know the part number and or size of the BB for a 2012 rockhopper 29er?

    I have been searching and searching and all it says on the specialized website is that its a Shimano octalink 73,but as I search I am finding different part numbers and lengths,and although I have been able to find the width witch I assume is 73MM I can't find the length as the are many.

    Also while I have this post,if I am intersted in upgrading to a better or stronger unit then what do I look for that fits my bike,I am interested in a bolt in part and I think this is a internal sealed cartridge unit.

    I am not interested in machining the outer left and right walls of my frame
    BB area to fit an external mount so I want to keep it internal,and could someone please give me info on the difference and what's required to use eaither?

    Thank you

  2. #2
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    Pull the cranks and measure the spindle length with Calipers or pull the BB and check the Part No on the existing one.
    Its no big deal to take your frame to an LBS and get the BB shell face if you can find a decent craiglist or ebay deal on a 9 speed Deore, SLX or XT hollowtech II crank. $5 ish I would imagine - doesn't really count as machining

  3. #3
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    So is there no upgrade for an internal bb or is this type of unit used on lower cost bikes and the external unit is #1

  4. #4
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    If you want to keep your existing crank you can use either a ES-25 or es-51 73mm BB (English thread) cartridge but you do need to know the spindle length (Length of the splined shaft) to keep the chainline correct. This can be measured with calipers. ES-51 has better quality bearings, better spindle etc. Octalink is not necessarily a bad system just older than Hollowtech 2 and used on the cheaper drivetrains these days - XTR use to be Octalink 10 years ago

    When I said check for deals on 9 speed HT 2 cranks - I forget to add BB in there - they should come with the BB.

  5. #5
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    Yeah I basically just want to keep the bike frame as an internal BB frame or use an internal bb

    Now are those the only 2 internal sealed cartridge units that will work for my frame,are there even better ones? And if I want to upgrade my crank arms and chain ring set to one of the most expensive best there is,then can I do this or are there models made for an internal bb?

    I apparently just warped my stock internal bb just simply sitting down peddaling the bike 70 miles,I took off the bolts that keep the crank arms on and looked in the center of my shaft since its hollow and spun the crank with the chain removed and the shaft spins oblong..should I still ride the bike if its shifting fine and working fine? A bike shop told me that this can happen and as long as nothings effected then its ok

    There is also a light ( sand in bearing sound) once in a while while the Sealed bb unit spins...lol..

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