Eccentric bottom brackets for 'normal' frames.....anybody make one?

Discussion in 'Downhill & Freeride' started by kidwoo, Jun 5, 2012.

  1. kidwoo

    kidwoo Celebrating No-Pants Day

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    Not so much to tighten chains on SS bikes, but more to mess with BB heights (and chainstay measurements if you really want to I guess).

    There's this for a BB30 shell

    http://www.universalcycles.com/shopping/product_details.php?id=41682

    They state 16mm of fore/aft movement, so theoretically, you could use one of these to drop your bb height 8mm. Not huge, but couple that with some selective headset and tire combos you might be able to get an appreciable measurement out of it.

    Any reason why this wouldn't work?


    And is there anything comparable for a threaded BB shell?
     
    #1 -   Jun 5, 2012

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  2. saruti

    saruti Turbo Monkey

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    that is why I've asked about CS length :)
    I was thinking about making one for myself
     
    #2 -   Jun 5, 2012
  3. Dogboy

    Dogboy Turbo Monkey

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  4. al-irl

    al-irl Turbo Monkey

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    i wouldnt imagine there is much room for manouver with a conventional bb shell
     
    #4 -   Jun 5, 2012
  5. LMC

    LMC Monkey

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    About 2.5mm off axle maximum, not really worth it IMO.
     
    #5 -   Jun 5, 2012
  6. kidwoo

    kidwoo Celebrating No-Pants Day

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    I don't think your deal is CS length but yeah, something like this would at least let you play with it and find out.

    Yeah, you're probably right. I was just curious. Those spindles really don't take up much room in there in an external, threaded BB setup. It would be interesting to try. In my ideal world, I'd just use the existing shell for a mount point and have the spindle hanging below the BB shell. Now that's change you can believe in.


    edit:
    Is that all? What kind of/brand spindle is that based off of?
     
    #6 -   Jun 5, 2012
  7. kidwoo

    kidwoo Celebrating No-Pants Day

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    #7 -   Jun 5, 2012
  8. WestCoastHucker

    WestCoastHucker Turbo Monkey

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    408.298.1540 - something tells me that the number you are looking for is in there somewhere. you just might have to look hard though....
     
    #8 -   Jun 5, 2012
  9. kidwoo

    kidwoo Celebrating No-Pants Day

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    I don't know man......sounds sketchy.


    1/4 inch 'eccentricity'. So if I understand that correctly, 1/8" or 3mm offset max. Definitely not worth it. Thanks y'all!
     
    #9 -   Jun 5, 2012
  10. dump

    dump Turbo Monkey

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  11. Pslide

    Pslide Turbo Monkey

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    Is anyone aware of an offset cup for my seat post?

    I'd like to make a bike where everything is off center if possible.
     
  12. frorider

    frorider Monkey

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    those forward components EBB's (for std BB shells) were something i looked into years back but it appears their site stopped working last year. at any rate, the amt of eccentricity was not enough (I was hoping to lower BB height, in combination with other things as woo is proposing).
     
  13. Sandwich

    Sandwich just shake your rump
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  14. EVRAC

    EVRAC Monkey

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  15. xy9ine

    xy9ine Turbo Monkey

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    that sounds rad, actually. ~1.5" bb drop. could effectively shorten the cs & slam the bb in one fell swoop. i'm currently playing with my old pdc 8.25 in slammed mode (bb @ 12.5" w/ 6.75" travel f&r), and love the geo.
     
  16. LMC

    LMC Monkey

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    I was working it out with a 24mm spindle and assuming the BB cup would have to have 3mm wall thickness. If you have 19mm axle profile style cranks you could get 5mm eccentricity.
     
  17. kidwoo

    kidwoo Celebrating No-Pants Day

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    Cool thanks. I was going to bust out the calipers when I got home but with those kinds of 'gains' this seems kind of pointless to pursue.

    That BB30 setup seems like it might just barely be worth it. Not happening on the bikes I have right now though......
     
  18. WestCoastHucker

    WestCoastHucker Turbo Monkey

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  19. yetihenry

    yetihenry Monkey

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  20. Nick

    Nick My name is Nick

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  21. OGRipper

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    Cartridge BB and a couple of hose clamps?

    There I fixed it. :thumb:
     
  22. buckoW

    buckoW Turbo Monkey

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    On a 7000 series alu frame, I got my buddy to cut off the BB shell and weld on a new one from doner frame making my frankenframe 25mm lower. He heat treated it and I rode it a lot for testing and it didn't move at all. He told me it would not have worked if the frame was 6000 series aluminum because the heat treating would have been a lot more complicated. It wasn't pretty but it was solid and worked very well for my purposes.

    I imagine this is to get your hard tail bb height lower like on the old P bikes?
     
  23. Pslide

    Pslide Turbo Monkey

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    I don't mean to distract this thread from what is actually a valid idea, but man, look at the possibilities these days:








    PS - I'd like to stick a Phil Wood eccentric BB in a GT i-drive, just because.
     
  24. kidwoo

    kidwoo Celebrating No-Pants Day

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    Nah my hardtail sits at around 11". It's awesome. This would be for every other bike I own :D

    Not sure I want to go the full detatchment route, just kicking some ideas around.
     
  25. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Is there an option to do this that doesn't cost so much yet?
    From what I can see the three products available are the Exzentric, the Philcentric, and the now discontinued Forward Components EBB. The Exzentric and Philcentric are unreasonably expensive for the 3mm of adjustment you can get.
     
  26. jonKranked

    jonKranked Press Button, Receive Stupid

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    engineering: functional, strong, cheap.

    pick 2.
     
  27. trib

    trib not worthy of a Rux.

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    I was going to suggest what Buckow did.

    Lop the bottom off the existing BB shell, get fabricator to weld in new one. Helps if bike is steel.
     
  28. trib

    trib not worthy of a Rux.

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    even better, cut off old shell, weld in larger size shell to allow a proper eccentric hub. BB options galore.