How to get rid of tensioners and half links.

Discussion in 'General Questions' started by Beau, Oct 21, 2010.

  1. Beau

    Beau New Member

    Magic gears and half links will work. If you have the money, buy one of these-


    It's a tandem eccentric for bottom brackets on tandem bikes. It uses a euro BB so higher quality, better parts can be used too. It has an offset in it. It fits into any American bottom bracket shell. Say goodbye to one piece and BMX cranks!

    So you tension your engine chain with the wheel, then tension your pedal chain with the bottom bracket eccentric. The eccentrics are held in place using a wedge system similar to a stem. The eccentric costs about $35 give or take.

    (I don't know if this is a known part, but most of the people I know with gas bikes have no idea this even exists)

  2. motorpsycho

    motorpsycho Active Member

    that's a pretty cool thing there...but will it work on 20" frames? the reason i ask is because both of my bikes are 20" frames.
    i'm not understanding where this thing gets mounted.
  3. Beau

    Beau New Member

    They will fit anything with an American bottom bracket. American bottom brackets come in all the old cruisers and BMX bikes. This goes where one piece cranks normally go. You then buy a european bottom bracket that threads into the eccentric. That way you can run mountain bike/road bike/newer BMX bottom brackets.

    Like this-

  4. motorpsycho

    motorpsycho Active Member

    oh i understand now. the concentric allows you to adjust the cranks, to tension the pdeal chain.
    That's pretty cool, i have never seen one of them before.
    But what if the frame has the smaller hole already for 3 peice cranks?
    this can not be inserted into the smaller 3 peice crank hole.
    i am assuming "bottom bracket" means where the cranks go through the frame.
  5. Beau

    Beau New Member

    Yes, the bottom bracket is the bearings for the crank. If you already have the smaller one (european) it won't work.
  6. pbeggs

    pbeggs Member

    note these are made for a tandem bottom braket shell (which is about .080) larger than the "standard one piece crank shell" (i learned the hard way)
  7. Beau

    Beau New Member

    I have never had a problem