This drive mechanism does not use chaindrive or shaftdrive but has efficiency as chaindrive (in terms of gear teeth engagement) and requires less frequent maintenance. Extra length requirement due to pedals is removed and length of bicycle can be further reduced by using smaller front wheel.
Basic idea: Use internally toothed gear to rotate the hub of the wheel of the rear wheel.
Drive mechanism, broadly speaking, is an epicyclic gear integrated to internally toothed slewing bearing such that internal gear of slewing bearing acts as outer ring gear of said epicyclic gear.
Outer ring of slewing bearing is attached to carrier plate via U-shaped pegs overbridging gear ring and attached at radially outward side to the bicycle frame. Gear ring may optionally on its outward side be attached to eared plate which in turn may be journalled at its center to the center of outward face of the carrier plate. Pedals are attached to outward side of the gear ring of the slewing bearing or the said eared plate. Eared plate protects rider clothing from cogs.
Three planetary gears (P1), (P2) and (P3) and a Sun gear (S) is journalled to carrier plate via ball bearings. U shaped pegs are attached to carrier plate in the space between the planet gears.
Planet gears are meshingly engaged to gear ring of slewing bearing. One planet gear (P1) is engaged with hub of the rear wheel. (P1) is coaxially attached to outer race of ratchet bearing mounted on the hub shell of the rear wheel. To facilitate syncing of pedals while coasting (P1) is attached at its center to axle of the rear wheel. (P2) and (P3) are located on forward side of the center of rear wheel. Outer ring of slewing bearing may additionally fastened to hub the rear wheel with the help of ball bearing via an L-shaped rod. This may additionally reduce the wobbling of the rear wheel. Smaller wheel on the front may increase efficiency.
The drive mechanism is equipped with multi gear engagement system (MGES). According to (MGES) rear wheel on its faces are coaxally attached to inner gear rail which is externally toothed spur gear of smaller radius and outer rail which is internally toothed spur gear of larger radius. Sun gear (S) on its face is coaxially attached to anticlockwise oriented ratchet bearing which is meshing engaged to inner rail and planet gears (P2) and (P3) on its face is coaxially attached to clockwise oriented ratchet bearing which is meshingly engaged to outer rail. Ratchet bearings in (MGES) may be tipped with one ball bearing to prevent friction with wheel's face. (MGES) (especially via sun gear) helps apply force on a larger area and reduce wobbling.
Various variations can be implemented to reduce the weight and cost.
This dirve mechanism can be used in reverse trikes and unicycles (with appropriate orientation and arrangement).
In unicycles (MGES) works as antitipping mechanism. I have also invented better responsive bevel gear based steering mechanism for reverse trikes.