2 stroke 3speed Mid-Drive

Discussion in 'Frame Mounted Engines' started by reddbak, Mar 30, 2008.

  1. reddbak

    reddbak Guest

    After months of design work and weeks of fabricating I finally have something solid to show for my efforts. This chop will be my only means of transport for a while until I get our Celica resto finalised, so it has to be comfy and capable to carry a small load of shopping.

    As shown in the pic, assembly is unfinished but the configuration gives the gist of the drive-train from 3 ring crank throught to 18T Mid-Drive on the right-side, engine 10T sprocket to 44T on the 3 spd Shimano Mid-Drive hub with another 18T sprocket through to 18T rear sprocket on the left-side. The Steer-Tube is 6" up, 4" over with a 30 degree rake off vertical. The Risers are too long I reckon so they may be trimmed forward a few inches. But these and the custom bent handle-bars are polished metal.

    The polished metal fork blades are sitting into spring-loaded polished damper tubes off my son's old Huffy 24" Freestyler as is the Crank assembly, Swing-Arm and damper. The Saddle frame is extended to carry a milk-crate sized box of whatever I'm picking up and the main frame will have V-shaped bracing on either side for saddle-bags. I'm working on the engine cosmetics an after some slight mods, lube and torque-wrenching, re-assembly should be this week. At this stage the block and head have been sprayed wih Stove-Black to show off the soon to be polished fin edges and side-covers.

    I'll post an update a work progresses. Cheers Reddbak :grin:

    Attached Files:

    Last edited by a moderator: Dec 15, 2015

  2. Alaskavan

    Alaskavan Guest

    Cool. Be sure to let us know how the mid-drive works out.
  3. graucho

    graucho Active Member

    Sweet! how long is the bike so I can get an idea how you will fit on it? Good job, keep the photos coming.
  4. Demosthenese

    Demosthenese Guest

    neat man, keep us updated. Seeing your frame makes me want to start building them even more!
  5. reddbak

    reddbak Guest


    I'm a tad behind on this build again as the idea of positioing the Mid-Drive dropouts vertically has made chain lengths difficult. So I've positioned them horizontally and am in the process of attaining a satisfactory length comprimise between the pedal chain and engine to mid-drive.

    Mounting a suitable side-stand proved to be another bugbear, as mounting a normal unit in front of the mid-drive was interferring with pedalling. However. a modified rear dropout unit fits well on the mid-drive axle dropouts without interference.

    Two successes I had were fabricating my own dual-brake lever kit and 20mm thick rubber front and rear engine mounts from a sandpaper hand-block.

    I'm doing a search for info on servicing a Shimano 3speed cassette hub as I'm having difficulty removing the internal cassette. I figure this must be removed to insert the axle with shift-rods(?) in place. I have a schematic, compliments of oldroads.com which indicates no circlips or such holding it in place, so I'm baffled atm.

    The frame is inverted whilst all this is taking place, but I'll post update pics later this week.

    Last edited by a moderator: Dec 15, 2015