OMG Help me

Discussion in 'Introduce Yourself' started by lonewitch, Jun 8, 2014.

  1. lonewitch

    lonewitch New Member

    Started with a huffy mountain bike but ran out of room, just went a picked up a 3 speed internal gears and the rear sprocket hole is to small to fit flush. Please what do I need to do? Get the sprocket machined? I am new at all this but really I love it, the last it did not fit cost me 135.00 as I bought the bike new. Ok I am open for any advice, I have a 3 speed 26 inch huffy and I gotta make it work.

  2. professor

    professor Active Member

    Got a grinder or big rat tail file?
    Scribe a line with a divider around the existing hole to just the right size and start filing till you hit the line.

    The 3 speed may or may not hold up to the motor, no fast application of power (letting the motor slam against the hub gears) and no power shifting might let the thing live.

    I am using a SA 3 speed hub as a jackshaft and it is doing fine with a 212cc. BUT, the J shaft reduces the torque the hub sees (in exchange for it spinning real fast) - keep it oiled!!!
    Your motor torque is multiplied by whatever gear ratio you are using.
    I suspect the 3 ft pounds or so of torque will not hurt the hub even though it is multiplied unless it is whacked by inertia created by rpm.
  3. lonewitch

    lonewitch New Member

    Thanks I gotta be flush right?
  4. KCvale

    KCvale Motorized Bicycle Vendor

    Correct, a direct drive sprocket won't fit over an internal 3-speed Nexus or the like.

    I see 2 choices.
    Put a coaster brake wheel or 7-speed derailleur on the back for direct drive, or just go with a jackhaft shift kit as a 3-speed internal is awesome with an engine because ya, your rear DD sprocket needs to align true to your engine output sprocket and then spin true on both the horizontal and vertical planes unless you want to throw chain like it was confetti at a parade.
  5. lonewitch

    lonewitch New Member

    Ok thanks
  6. KCvale

    KCvale Motorized Bicycle Vendor

    Just passing on what I learned, hope it helps.