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Electric pedals win Barclays' cash | Bicycle business | News by BikeBiz
Electric pedals win Barclays' cash | Bicycle business | News by BikeBiz
**WINNER!** Barclays TakeOneSmallStep.co.uk (Stephen Britt) - Power Assistance Kits
- Thread starter rsscott
- Start date
Mark Cavendish has a battery up his jumper and 1.5kw motors in each foot which transfer power to the pedals - the authorities haven't sussed it yet, but I know what I know.
Colin
It's fuel cells doing the charging, supplied by the methane gas!Mark Cavendish has a battery up his ****
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This system makes a lot of sense to me. I have a 13 mile ride with 3 climbs. Anything that makes it less daunting is great.
I already know that my pimped up drop handle tourer is faster than my Agattu, these pedals would be a great bolt on that could just make the hills a little speedier, as long as the power covers the weight/efficiency costs!
I already know that my pimped up drop handle tourer is faster than my Agattu, these pedals would be a great bolt on that could just make the hills a little speedier, as long as the power covers the weight/efficiency costs!
The fact that the battery can't store any useful energy and the whole principle of operation is mechanically flawed aside, they aren't a bad idea.
I'm currently working on a system which is powered entirely by Fair Trade Trousers and Brizillian Peace Crisps for the 2011 entry. You might want to wait and see what this brings before backing the electric pedal idea.
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Intriguing Stephen!
The only reason I can see this not working, baring the engineering practicalities of course, is the feeling the rider will have in resisting the pedal torque. A power output of 100W per foot, with a cadence of say 60 rpm implies a torque on the foot of about 15.9 Nm. This does not sound unreasonable, but I cannot imagine what this would feel like. This should be easy to test with a torque wrench lash up and someone twisting the pedal against your foot. Have you tried it? Does it feel OK?
What would you say the advantages of this approach are over a crank based motor?
The only reason I can see this not working, baring the engineering practicalities of course, is the feeling the rider will have in resisting the pedal torque. A power output of 100W per foot, with a cadence of say 60 rpm implies a torque on the foot of about 15.9 Nm. This does not sound unreasonable, but I cannot imagine what this would feel like. This should be easy to test with a torque wrench lash up and someone twisting the pedal against your foot. Have you tried it? Does it feel OK?
What would you say the advantages of this approach are over a crank based motor?
Well, to oppose a torque of 15.9 Nm acting about the spindle of the pedal (assume the pedal width is 100 mm), there would be about 320 Newtons acting acting at the edge of the pedal (15.9/0.05 = 320 N). To resist this force at the edge of the pedal, it would feel like a 33 Kg weight acting on your foot. (F=MA : M=F/A = 320/9.81 =33) If you eased this pressure off the sole of your foot, the pedal would spin.
I think to constantly press on the pedal with what, "feels like" 33 Kg, would be uncomfortable and you would be constantly battling to stop them from spinning under foot. You would even have to press down with what, "feels like" 33Kg on the upstroke pedal to stop it from spinning.
I cant think of any advantages to this system because it doesn't work.
I once heard a man on the Jeremy Vine show suggesting that all of our energy problems could be solved by installing turbines into the rainwater drainpipes on our houses. His theory being that we tend to put our house lights on when it is gloomy and overcast. These conditions, so he claimed, are usually associated with rain, so the rainwater flowing through the drainpipes would power the turbine and power the lights in our home.
These pedals belong in the same category as the rainwater turbine (or propellor as the caller put it).
Whatever next, electric motors to turn the generators in our power stations? That would be a zero emission power station. How splendid!
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Yes, I have just nipped out to measure my pedal and agree with this calculation. To have any hope of providing 100W of assistance per foot is clearly going to need much wider pedals than normal. I find it difficult to see how anyone would comfortably cope with more than 30W per foot. Even then having to keep downward pressure on the upstroke must feel very strange.
Due to the symmetrical nature (rider must rotate the motor against the torque), it will be impossible to get more than 1:1 assistance out of this arrangement.
I wrote some total rubbish here:
1:0.3 would be useful - I suspect that I cycle most of the time with about this level of assistance on my Panasonic crank drive based bike, but I would emphasize that this would be the maximum.
What I cannot get my head around is what happens when the pedal is outside the 3 O'clock position. For instance, when the crank is at 12 O'clock and 6'Oclock, the rider will be not providing any torque at all if the foot is being pressed straight down. But do we ride like this? Or do we naturally push the pedal forwards when in the 12 O'clock position? Whatever happens, I am sure that the pedal motor can only supply a maximum of 0.3 times the maximum torque provided by the rider on the down-stroke.
I have not fully thought through the up-stroke yet, but I suspect that the best thing that can happen here is for the motor to be off, otherwise you are essentially pushing the wrong way trying to prevent the pedal spinning.
Far too simplistic a statement. This is quite complicated to work out, but I do not think that assistance will be likely to reach 1:1. When the crank is in the 3 O'clock position, the rider will be providing the maximum torque. When in this position, the maximum assistance will be achieved when the pressure of the rider's foot is just sufficient to prevent the pedal being pushed away from the foot by the pedal motor torque. In this case the assistance provided by the pedal motor will be proportional to half the pedal wdth divided by the crank length. So, for example with a 17cm crank, 10cm pedal, the assistance will be (10/2)/17, about 1:0.3.
1:0.3 would be useful - I suspect that I cycle most of the time with about this level of assistance on my Panasonic crank drive based bike, but I would emphasize that this would be the maximum.
What I cannot get my head around is what happens when the pedal is outside the 3 O'clock position. For instance, when the crank is at 12 O'clock and 6'Oclock, the rider will be not providing any torque at all if the foot is being pressed straight down. But do we ride like this? Or do we naturally push the pedal forwards when in the 12 O'clock position? Whatever happens, I am sure that the pedal motor can only supply a maximum of 0.3 times the maximum torque provided by the rider on the down-stroke.
I have not fully thought through the up-stroke yet, but I suspect that the best thing that can happen here is for the motor to be off, otherwise you are essentially pushing the wrong way trying to prevent the pedal spinning.
The inventor says there are pressure sensors on the pedals Tangent, no motor power applied below a certain point, so top and bottom dead centres are not a problem.
I still think the idea useless though and believe the inventor is deluded. A clue comes from his insistence that it's 100 watts per pedal amounts to a 200 watts system. Clearly it's only 100 watts maximum at any time, and when the top and bottom dead centres are taken into account, the potential average will be well under that. However, as you imply, nothing like that sort of power can be applied without twisting the pedals from under the rider's foot. From experience of what happens when pedal bearings start to bind slightly, the foot's resistance to pedal twisting force is very low.
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I still think the idea useless though and believe the inventor is deluded. A clue comes from his insistence that it's 100 watts per pedal amounts to a 200 watts system. Clearly it's only 100 watts maximum at any time, and when the top and bottom dead centres are taken into account, the potential average will be well under that. However, as you imply, nothing like that sort of power can be applied without twisting the pedals from under the rider's foot. From experience of what happens when pedal bearings start to bind slightly, the foot's resistance to pedal twisting force is very low.
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Yes, I like to be open minded, but this is looking more doomed the more I think about it. For instance, I calculated that a rider travelling at constant speed, with a cadence of 60rpm, and generating an average 100W would be applying average torque of about 16Nm. On a standard 17cm crank this would mean an average tangential force of 94N, or about 9.5kg. I would not have thought that the average electric bike rider would want to push harder than this for very long. But even riding like this, the absolute best that can be achieved is another 30W from the pedal motors (unless the inventor has found a way round Newton's third law ). As indicated by tillson, 100W motors would be completely unthinkable to all but the fittest riders and they would not want them anyway.
). As indicated by tillson, 100W motors would be completely unthinkable to all but the fittest riders and they would not want them anyway.I wish the winning inventor was a member of this forum, we would have some pretty entertaining discussions !
Nothing to stop him is there.I wish the winning inventor was a member of this forum, we would have some pretty entertaining discussions !
He can obviously defend the indefensible successfully. He convinced Barclays and they are a vast business organisation that would never, like their competitors, make a bad decision on an investment. Therefore he must be right and all the doubters on here are wrong.
Who would you trust: a bank with their investment professionals or some little guy who rides a push-bike (and even needs help from a motor to do that properly) called "Tilson" and co.
Think very carefully for at least a nanosecond before you all shout "Tilson" (Other posters are available with similar levels of common sense)
Colin
The inventor Stephen Britt is member Steve123456 and he has responded politely in this thread and defended his invention. That's how I knew of his claim of 200 watts.I wish the winning inventor was a member of this forum, we would have some pretty entertaining discussions !
Reply from Steve123456
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Quite, and a bank like Barclays would never ask for the opinion of scientists, engineers or indeed anyone with moderately above average common sense. That would give the impression that they did not know what they were doing and could not make decisions. That would never do.
No, the most important thing about an idea, good or bad, is that the bank sells it on as quickly as possible before too many people work out which way it is. Of course if the bank has an inkling that it might be a bad idea, it would chose to sell it to someone who did not care too much either way, such as a pension fund manager.
The advantage of a complicated idea, such as this one, is that it takes a bit longer for people to work out if it is good or bad and so allows more time to shift it.
I am sure that Barclays are not intending anything like this here. It is just a comment on the way they operate.
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