Pins Out: Freewheeling pedal cycle - great for short trips and exercise!
Pins In: Pedal Start motor-assisted bicycle - great when you need a boost!
Now you have the best of both worlds!!
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Transmission arrangements for light motorized bikes
There are 3 ways of powering a chain or belt-driven motorized bike with an auxiliary motor:
- Common fixed transmission whereby the driven sprocket is fixed to the rear wheel.
- Freewheeling transmission where the driven sprocket is mounted on a one way freewheel. The motor cannot be pedal-started.
- Hybrid Motor-assisted/Pedal transmission whereby the driven sprocket can be selected and deselected.
Common fixed transmission
The common fixed transmission has been around for decades. Typically, a sprocket is fixed to the spokes of the rear wheel of the bike. The wheel cannot freewheel (ie rotate faster than the motor and chain transmission allow) and the commonly available sprocket fixture tends to be hard on spokes with a high incidence of spoke breakage.
The drag of the transmission prevents usage as a conventional bicycle, but the common fixed transmission has ONE HUGE ADVANTAGE - A PEDAL-START MOTOR.
Freewheeling transmission
One common method of getting around the sprocket-spoke fixture so that the bike can freewheel down hills is to mount the sprocket on a unidirectional freewheel seated on the wheel hub. This means that (i) you need another means to start the motor; and (ii) you need a new hub that may not fit your preferred pedal gear system, especially cassette hubs.
The common engine-starter in such an arrangement is a rope-pull starter, which is great for muscle-building but a hassle in the middle of traffic, and subject to unexpected failure, in which case you are stuck. As many of us knows, starting engines can be problematical as we have had the experience of a hard-to-start lawn mower, wipper-snipper or chain saw.
Hybrid Motor-assisted/Pedal transmission
The HybriPed HPS is the only genuine hybrid power transmission that this writer is aware of that gives you the benefit of pedal-starting the bike engine, as well as being able to use your bicycle as a conventional bicycle.
The HPS replaces the old standard sprocket fixture that comes standard on a common fixed transmission arrangement, but you can select and deselect between pedal and motor-assisted cycling. It only takes a few moments to switch over.
HybriPed Hybrid Power Sprocket (HPS) Explained
The HPS has three main parts, sprocket, coupling pins and spoke fixture.
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| Motor-assisted bicycle fitted with HPS | Sprocket and coupling pins | Spoke fixture |
Operation of the transmission is summarised as follows:
Pedal mode
In this mode, the rider pedals the bicycle without any motor assistance, motor chain movement or any felt resistance whatsoever. The 2 coupling pins are removed from the sprocket and spoke fixture and held elsewhere.
Motor-assisted mode
In this mode, the rider has full motor-assistance and easy pedal-starting of the motor with the sprocket locked to the wheel. The coupling pins are insert between the sprocket and spoke fixture.
Each coupling pin has a retaining ball at the inner end of the shaft and retainer at the outer end.
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| Inside face of spoke fixture | Motor-assist mode: coupling pins in place | Switch to pedal mode: coupling pins being withdrawn |
Operation
HybriPed YouTube videos illustrate the coupling pin operation. The pins are kept in a holder when not in use and then manually inserted through 2 of the sprocket holes into the spoke fixture.
The spoke fixture has two tubes that match a series of holes in the sprocket so that the coupling pins can be installed between the sprocket and the spoke fixture, effectively locking the two parts together.
The sprocket spins on a mechanical bearing that replaces the spacer outside the wheel cone on a standard axle. It will fit on a common 135mm dropout axle.
You must stop the bicycle to switch between pedal mode and assisted mode.
HybriPed Technical Benefits
- Pedal start engine
- Fits a wide range bikes
- Extend engine life - the less you use the engine, the wear and tear there is
- Reduce fuel consumption -
- Fewer broken spokes
- No transmission drag in pedal mode
- Only one moving part
Pedal start engine
When the HPS is in 'Motor-assist Mode', you have a pedal-start engine, which means that you can put the hassle of engine-starting behind you. No more unnecessary engine idling. Never worry about the engine stalling again. When you come to a standstill, let the engine stall. When the traffic light turns green, simply pedal off, let out the clutch and you are away. This is the recommended practice with a pedal-start engine and you save even more fuel!
Of course the HPS is not a clutch. You don't have continuous motor-assist and freewheeling bicycle at the same time. If that is what you want, then the HPS is not for you.
Fits a wide range bikes
Many road, mountain or hybrid style bikes are readily suitable. Read the section Will it fit your bicycle?
Extend engine life and reduce fuel consumption
You don't need power-assistance most of the time. When the engine is not in use, it does not wear, does not consume fuel and does not require maintenance.
The engine does not need to be kept warm, but the benefit of a pedal-start engine is that it is easy to start, even when it is cold.
Fewer broken spokes
The spoke fixture uses twice as many fasteners and seems to lock the motor-drive spokes into a rigid truss around the wheel hub spoke flange.
So far, the prototypes have had no broken spokes over a duration of two years.
No transmission drag in pedal mode
When in pedal mode, the transmission components - chain, sprocket and bearing - are completely separate from the pedal chain and wheel.
Only one moving part
The HPS has only one moving part, the mechanical bearing. It is proving to be very reliable in service and is expected to have a service life of many thousands of kilometres.
Patent Protection
Intellectual property embodied in the HybriPed Hybrid Power Sprocket (HPS) is protected under Patent Cooperation Treaty (PCT) International Patent Application No: PCT/AU2008/000196
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