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  1. #1
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    Eccentric Bottom Bracket Conversion

    I have an '09 Rocky Mountain Hammer 29er hardtail frame with an eccentric bottom bracket, I'd like to get rid of the EBB in the interest of saving weight and complexity and am wondering if a conversion kit exists. I really don't need an EBB since I use gears.

    I was able to find a converter for BMX bottom bracket shells (Universal Cycles -- Truvativ American to Euro BB-Shell Conversion) but not 54.5 mm inner diameter EBB shells. Does anyone know if such a converter exists?

  2. #2
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    Quote Originally Posted by azmtbkr81 View Post
    I have an '09 Rocky Mountain Hammer 29er hardtail frame with an eccentric bottom bracket, I'd like to get rid of the EBB in the interest of saving weight and complexity and am wondering if a conversion kit exists. I really don't need an EBB since I use gears.

    I was able to find a converter for BMX bottom bracket shells (Universal Cycles -- Truvativ American to Euro BB-Shell Conversion) but not 54.5 mm inner diameter EBB shells. Does anyone know if such a converter exists?
    A converter is not going to be any lighter or less complex than the EBB insert. It still needs to fit in the frame and hold securely.
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  3. #3
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    Quote Originally Posted by shiggy View Post
    A converter is not going to be any lighter or less complex than the EBB insert. It still needs to fit in the frame and hold securely.
    I've not weighed an adapter like the one linked but I have to think it weighs significantly less than the half lb chunk of solid aluminum EBB.

    It also has a better clamping design; I have to torque the set screws quite a bit to keep the EBB from slipping and it is starting to ovalize the BB shell - not a major concern but still not ideal.

    I may end up trying to have one fabbed up, seems like a fairly straightforward design.

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    Quote Originally Posted by azmtbkr81 View Post
    I've not weighed an adapter like the one linked but I have to think it weighs significantly less than the half lb chunk of solid aluminum EBB.

    It also has a better clamping design; I have to torque the set screws quite a bit to keep the EBB from slipping and it is starting to ovalize the BB shell - not a major concern but still not ideal.

    I may end up trying to have one fabbed up, seems like a fairly straightforward design.
    Niner's EBB is a similar design. Creaking is a known issue, but any insert will creak if the shell I not reamed (and faced in the case of the Niner).

    I have a Co-Motion EBB insert in my frame with set screws. The Co-Motion is a very simple internal wedge type (so I do not need to use the set screws) and reasonably light. I have not touched it in 4years and it have never made a sound.
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  5. #5
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    Interesting, I'll have to check those out. Thanks.

  6. #6
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    Quote Originally Posted by azmtbkr81 View Post
    Interesting, I'll have to check those out. Thanks.
    Co-Motion Cycles
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  7. #7
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    Quote Originally Posted by shiggy View Post
    I went to their site to look at a bike recommended to me.
    The Co-motion Divide Rohloff. I was surprised at what appeared to me to be a lack of detail in the description. No mention of what tyres fit inside the stays nor brand/type of spokes. Considering their prices suggest a premium product I was expecting a little more. Not suggesting they dont do a good bottom bracket conversion. Just mentioned my waffle after seeing your link to a companies site I visited in the last couple of days.
    For the money their bikes command I could tour extensively on a lesser quality bike so I was expecting something much more from their site.

  8. #8
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    Eccentric Bottom Bracket Conversion

    Quote Originally Posted by rifraf View Post
    I went to their site to look at a bike recommended to me.
    The Co-motion Divide Rohloff. I was surprised at what appeared to me to be a lack of detail in the description. No mention of what tyres fit inside the stays nor brand/type of spokes. Considering their prices suggest a premium product I was expecting a little more. Not suggesting they dont do a good bottom bracket conversion. Just mentioned my waffle after seeing your link to a companies site I visited in the last couple of days.
    For the money their bikes command I could tour extensively on a lesser quality bike so I was expecting something much more from their site.
    This is NOT a BB conversion. It is purpose built eccentric bottom bracket.

    Few, if any, companies detail the spoke brand used in wheels of complete bikes. The spec is subject to availability.

    If you have further questions about their bikes, contact them.

    I have know these guys from the time it was just two of them in a shed doing custom work. Co-Motion has grown into a top notch manufacturer of solid bikes.
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  9. #9
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    Quote Originally Posted by shiggy View Post
    This is NOT a BB conversion. It is purpose built eccentric bottom bracket.

    Few, if any, companies detail the spoke brand used in wheels of complete bikes. The spec is subject to availability.

    If you have further questions about their bikes, contact them.

    I have know these guys from the time it was just two of them in a shed doing custom work. Co-Motion has grown into a top notch manufacturer of solid bikes.
    Hey Shiggy
    I mentioned a very minor niggle.
    I very much like their bikes and am impressed by their reputation.
    However my experience is different than yours.
    My current bike (Moulton) and the Surly build I'm looking at both mention their frames max tyre size fitment as well as their spokes brand/type so sorry if yours doesn't.
    I wondered if spec was subject to availability - thanks for clearing that up.
    If you know the folks at Co-motion well it might go down better from you better than me if you informed them that their Divide Rohloff download had incorrect spec on it.
    The spec sheet I downloaded mentions both Aeroheat rims and 26" tyres which is I believe a mistake considering its a 29er bike.
    As for the bracket, I referred to it as a clarification that I wasnt knocking their product which I obviously failed to do well judging from your post - please excuse my rambling uneducated mind. I followed the line that the first few posts referred to a converter. My post was about my "misadventure" within Co-motions website. Co-motion come highly recommended to me hence my visit to their site.
    If I didnt believe they make good product I wouldnt have been checking them out. Like I said, it was a minor niggle - they are bike builders and not web masters so I dont expect perfection, but I do believe not informing potential buyers of max tyre size fitment to frame is an important oversight - but not the end of the world.
    I hope this makes what I was trying to say clearer without initiating a flame war.
    Not sure what the reputation notification is on my tool bar as when I click on it I'm taken to my past posts. Perhaps as a mod you might clarify this as well should you have the time.
    Last edited by rifraf; 02-11-2013 at 04:27 PM.

  10. #10
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    Eccentric Bottom Bracket Conversion

    Quote Originally Posted by rifraf View Post
    Hey Shiggy
    I mentioned a very minor niggle.
    I very much like their bikes and am impressed by their reputation.
    However my experience is different than yours.
    My current bike (Moulton) and the Surly build I'm looking at both mention their frames max tyre size fitment as well as their spokes brand/type so sorry if yours doesn't.
    I wondered if spec was subject to availability - thanks for clearing that up.
    If you know the folks at Co-motion well it might go down better from you better than me if you informed them that their Divide Rohloff download had incorrect spec on it.
    The spec sheet I downloaded mentions both Aeroheat rims and 26" tyres which is I believe a mistake considering its a 29er bike.
    As for the bracket, I referred to it as a clarification that I wasnt knocking their product which I obviously failed to do well judging from your post - please excuse my rambling uneducated mind. I followed the line that the first few posts referred to a converter. My post was about my "misadventure" within Co-motions website. Co-motion come highly recommended to me hence my visit to their site.
    If I didnt believe they make good product I wouldnt have been checking them out. Like I said, it was a minor niggle - they are bike builders and not web masters so I dont expect perfection, but I do believe not informing potential buyers of max tyre size fitment to frame is an important oversight - but not the end of the world.
    I hope this makes what I was trying to say clearer without initiating a flame war.
    Not sure what the reputation notification is on my tool bar as when I click on it I'm taken to my past posts. Perhaps as a mod you might clarify this as well should you have the time.
    Go ahead and send them the errors you found.

    No idea what you are talking about with the rep notification.
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