Dynamo leg powered ebikes - a good idea?

[albion]

https://www.bikeradar.com/news/2026-icetrike-e-trike-pers

Whilst that hew example is a recumbent trike it sounds a useful variation of a torque sensor equipped bike.

 

[Ming the Merciless]

It also goes backward if you back pedal. 0-20 mph in 3 secs…

 

[steveindenmark]

ICE makes great trikes. But this will not be cheap.

 

[classic33]

Pedal by wire.
What happens when the battery dies, and is your pedalling supplying the battery or the motor. The piece claims it's doing both.

 

[albion]

Pedal by wire.
What happens when the battery dies, and is your pedalling supplying the battery or the motor. The piece claims it's doing both.

Probably true, it not being isolated from the battery output, My concern is low efficiency. If 75% or less it might be a big hindrance.

 

[classic33]

Probably true, it not being isolated from the battery output, My concern is low efficiency. If 75% or less it might be a big hindrance.

I was interested in a cargo quad with a similar system, but was put off by its manufacturer not being certain about the range of the battery. Anything from 30 kilometres to 100 miles being given. After the battery died, that was it. The pedals didn't supply enough power to move it, only sufficient to generate a current that allowed the battery to supply the motor(s), which provided the means of propulsion.
The pedals are a means of trying to get round the current regulation of "the cycle must be fitted with pedals which are able to propel the cycle".

 

[albion]

Thats the thing, range is infinite if your pedalling does 100% of the propulsion.
I probably do 50 to 75% of the work on my ebike. But with a dynamo I would have to work towards 33% harder to get the same range on a 75% efficient dynamo. And that 75% might be an optimistic guess.

 

[classic33]

Thats the thing, range is infinite if your pedalling does 100% of the propulsion.
I probably do 50 to 75% of the work on my ebike. But with a dynamo I would have to work towards 33% harder to get the same range on a 75% efficient dynamo. And that 75% might be an optimistic guess.

Be worse still if when you're freewheeling the regenerative braking can't be switched off.

If you're pedalling to recharge the battery, and generating a current to allow the battery to power the motor, you're not propelling the cycle with them. Which falls outside current UK regulations.

 

[Bristolian]

If you're pedalling to recharge the battery, and generating a current to allow the battery to power the motor, you're not propelling the cycle with them. Which falls outside current UK regulations.

Based on your previous quote "the cycle must be fitted with pedals which are able to propel the cycle" as long as the act of pedalling causes the cycle to move then surely that requirement is met.

AFAIK, there is nothing in the UK regulations that states how the act of pedalling has to result in movement. In a typical analogue cycle the motion of the pedals doesn't in and of itself result in the bike moving, there are chains, gears and sprockets involved too.

 

[classic33]

Based on your previous quote "the cycle must be fitted with pedals which are able to propel the cycle" as long as the act of pedalling causes the cycle to move then surely that requirement is met.

AFAIK, there is nothing in the UK regulations that states how the act of pedalling has to result in movement. In a typical analogue cycle the motion of the pedals doesn't in and of itself result in the bike moving, there are chains, gears and sprockets involved too.

Can the cycle move without the battery? Chances are it'll not move without it in the system, and when the battery dies there'll be no moving no matter how much you pedal.

 

[Bristolian]

Can the cycle move without the battery? Chances are it'll not move without it in the system, and when the battery dies there'll be no moving no matter how much you pedal.

Can your analogue bike move without a chain? To paraphrase: Chances are it'll not move without it in the system, and when the chain breaks there'll be no moving no matter how much you pedal.

Unless you ride a penny-farthing or a unicycle (or something similar) the pedals do not directly move the cycle

 

[classic33]

Can your analogue bike move without a chain? To paraphrase: Chances are it'll not move without it in the system, and when the chain breaks there'll be no moving no matter how much you pedal.

Unless you ride a penny-farthing or a unicycle (or something similar) the pedals do not directly move the cycle

But in a pedal by wire system you're pedalling either to charge the battery(ies) and/or pedalling to allow the battery(ies) to supply the motor, that pushes the cycle forward.
There is no direct drive link between the pedals and the drive wheel(s). Which reflect the regulations as first drafted, carried over to the current regulations.

Fit a petrol engine* that does exactly the same and it instantly becomes a motor vehicle.

*You pedalling pumps the petrol from the fuel tank to the engine. No pedalling, no petrol, no power.

 

[roley poley]

slightly off subject but i had a dynamo powered system for my lights which charged 4 AA batteries through a bridge rectifier to keep them ON when i stopped at a junction or turning (eg) right at a junction in the middle of the road...it was supposed to be able to charge the unit up to do so if you left the dynamo on during the day...poo i had to charge my nickle cads from the mains to make it do the job

 

[Shut Up Legs]

I had a brainwave recently: a radical new approach to e-bikes, where the motor efficiency is second to none. In a typical e-bike, your legs don't get enough of a workout, so in my new improved version, you use your legs and feet to turn these things called pedals, which then propel the e-bike forward without any draining of battery power, and almost no environmental impact. It's all quite ingenious, really: I call the new improved version a "bicycle".

 

[Electric_Andy]

One would have to ask: the main research question they seem to be answering is "how do we get rid of an overly long chain?". Is a long chain really much of a problem? Or is this design answering a question that no-one asked? I'm all for improving things, but the very nature of a recumbent means that it's size and shape is different to a standard bicycle, thus it makes sense that the longer chain is part and parcel of that difference.

The ride-by-wire throttles on motorcycles is another example. The only advantage being that you can never suffer with a snapped throttle cable. But that's not a very common issue anyway, certainly not common enough to need a more expensive alternative?