Electric pedals!

Mycroft

New Member
not sure where to post this so going for (hopefully) maximum exposure

http://bicycledesign.net/2010/06/fast-forward-powered-pedals/

a new concept for an electric bike.

"Stephen Britt is one of three finalists in the UK based Barclays ‘Take One Small Step competition’, where he could win £50,000 to develop his idea into a business. His “Fast Forward” entry, the only cycling related product in the contest, is a pair of electric assist pedals. "

click the link and vote for him so he can get thew £50,000 to develop the idea :smile:
 

gaz

Cycle Camera TV
Location
South Croydon
£200? i think i will go for look carbon pedals!
 

Night Train

Maker of Things
Hmmm, a motor in the pedal that adds to the turning moment affecting the crank.

So what does it react against?
Doesn't it just mean that it is trying to rotate the pedal under the ball of the foot?
What it it gets wet and slippery?

If it clips on then would it transfer the extra driving forces to the ankle joint?
 

emulsifier12

New Member
Location
Nuneaton
This idea does not make technical sense in my head... How would a motorised pedal help you pedal? Is the pedal clipped onto the foot?
Another thought...
An increase of almost 1kg on the pedals? Would this not have a similar effect that heavy wheels have on a bike?
 

Beardie

Well-Known Member
I can see so many problems with this that it is diffficult to know where to start. But surely the biggest is that to stop the motorised pedal simply rotating uselessly under your foot, you would have to press down on it as hard as if you were pedalling normally.
 

Arch

Married to Night Train
Location
Salford, UK
emulsifier12 said:
This idea does not make technical sense in my head... How would a motorised pedal help you pedal? Is the pedal clipped onto the foot?
I met the chap last week, and he said a lot of people have trouble with the concept. Makes perfect sense to me. The pedal 'wants' to rotate on the shaft. Your foot stops it doing that, so it rotates the crank instead.

beardie said:
I can see so many problems with this that it is diffficult to know where to start. But surely the biggest is that to stop the motorised pedal simply rotating uselessly under your foot, you would have to press down on it as hard as if you were pedalling normally.
Yes, it's electric assist: pedelec, not a throttle motor. You pedal, and when you pedal hardest (IE when you most need help), it gives you a little boost.

If it works (and I admit, I only got to try it pedalling a bike in a stand by hand), it has a few advantages. Cheaper and lighter than a custom built electric bike, cheaper and easier to add than an add-on electric kit, and fittable to any bike you might already have...

Electric assist, like any cycling, comes in many shapes and forms. This isn't the solution to all uses, but if it provided a realtively cheap and easy way for someone to overcome their doubts or lack of confidence abut coping with a commute, or a particular hill, and gets them on a bike, it's done a good job. Eventually, they might realise thay can do without - then it's easy to remove and go back to normal pedals.
 

Smokin Joe

Legendary Member
"Yes, it's electric assist: pedelec, not a throttle motor. You pedal, and when you pedal hardest (IE when you most need help), it gives you a little boost."


The guy needs to take a course of physics lessons.

Arch, how can it give you a boost? As Night train says, what is it reacting against?

It's a completely daft idea, I can't see how it could possibly work.
 

Arch

Married to Night Train
Location
Salford, UK
Smokin Joe said:
Arch, how can it give you a boost? As Night train says, what is it reacting against?
Your foot?

It certainly seemed to work when turned and operated by hand (a button on the pedal detects pressure and turns the motor on). If you prefer not to believe me, that's up to you, but I've actually seen and touched it in prototype form, and can't see why it wouldn't work.
 

palinurus

Velo, boulot, dodo
Location
Watford
I'm curious anyway.

Sure, at the moment, my preferred technical solution to powering a bike is the Gruber assist concept. Comes at a high price though. Pedals are easy to fit to any bike so, assuming they work well enough, there is a some advantage over other methods of adding electric assist to a bike/trike.

Already a bit of a plane on a treadmill-type discussion. I'll sleep on it.
 

bikepete

Veteran
Location
York, UK
As Arch says it reacts against your foot. The front of the pedal pushes up a bit harder, and the back a bit less hard. The (geared down) motor reacts against this to apply a moment to the rotating crank, doing work on it and so helping propel the bike.

The work the rider puts in to their pedalling should be unchanged. Any extra work needed to oppose the front of the pedal pushing up is balanced by the reduction from the back of the pedal not pushing up so much. As it's activated in proportion to the pressure applied by your shoe to a pressure pad at the middle of the pedal, if the force at the back edge ever goes to zero (when your foot would lift off it) then the assist would cut out or reduce anyway - it's self limiting. The same system means if your foot slips off or whatever it will simply stop.

As the pressure between your foot and the pedal is distributed more towards the front of the pedal when it's adding power, you will presumably need to resist ankle movement with a bit more force via the Achilles tendon, as the pedal force has a slightly longer moment arm. But this is essentially a static force so will do no significant work. Opposing static forces does tire muscles, though, so I guess your calf muscles could tire a bit quicker with the pedals switched on. But I think it would be a fairly small effect, especially as you'll rarely be at full power.

The target for the production model is apparently 100W per pedal MAXIMUM assist.

To get 100W power at say 60 rpm, you'd need a torque of approx 16 Nm as per e.g. here.

Assuming the pedal is say 6" long (15 cm = 0.15 m) then the difference in force between the front and rear ends of the pedal would need to be around 16 Nm / 0.15 m = 106 N. Expressed as kilograms of force that would be about 10 kg, so 5 kg extra push up on the front and 5 kg less push up at the back. I concede that is a 'best case' figure as the load would not be concentrated at the front/back edges. But + or - 5 kg seems reasonable given it's MAX power, when you're already fairly heaving at or standing on the pedals, applying presumably a decent portion of your body weight.

And remember the pressure sensor control system means it will only exert these forces when your foot is already stomping down with greater force. If your foot pressure reduces, so does the assist.

You'd want to use reasonably stiff-soled shoes I guess.

But there is no basic reason why this won't work.

Disclosure - the inventor Stephen Britt is a subscriber to Velo Vision, and I helped him distribute leaflets and show the prototype system to all comers at the recent York Cycle Show, as seen (fourth pic down) here:

http://www.velovision.com/cgi-bin/show_comments.pl?storynum=1114

I also sent out details of it to my media contacts which resulted in its appearance on the Bicycle Design blog, in Wired magazine, on Engadget, on road.cc, on Tom's Guide and more. Any help I have given it has been free of charge and I have no stake in the invention. My motivation is to see £50k taken from Barclays bank and go to a cycling invention rather than to something less worthy, especially to a cycling invention which (like other electric bikes) has some potential to tempt people into cycling who might not otherwise give it a try.

Incidentally the inventor is IMO not daft, stupid, physics-challenged or a con-man. He seems like a very nice technically-minded chap with a good idea but whose strengths are not necessarily in explaining it or in marketing (Exhibit A being his 'promotional' video at the link below!). I think it's worth any help I can give it to get him the £50k to commercialise it (that's not even a lot of money for such a project).

If anyone else thinks it's worth a moment of your time to encourage go to:

https://www.takeonesmallstep.co.uk/Entry/View/2462

and give it your vote!
 

JtB

‘Diversity’ makes the world a beautiful place
Location
North Hampshire
10 miles range doesn't sound much, but I guess if you get 10 miles worth of up-hill assistance that's not bad. Only thing is, going up hill is my favorite bit.
 

Arch

Married to Night Train
Location
Salford, UK
Smokin Joe said:
Sorry, but for all the technical jargon it would be about as much use as sticking a bit of card from your seatstay to the spokes so it sounded like a motorbike.
And your engineering credentials are...?

Shaun - I guess the amount of force needed to activate the motor means that it only cuts in when you push really hard - IE up hill. You're not limited to 10 miles of range, just 10 miles of help. Which might be enough to get someone commuting who wouldn't otherwise...

Going uphill is a real barrier to some, and a percieved barrier to many, hwever much any of us like it (and I don't, personally, except that it gets me to the top for a nice free ride the other side!)
 
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