I have had a look at this http://www.britt-technologies.co.uk/ can't for the life of me see how it's going to work, but if it does - Wow
So pick a few holes in ti as per normal.
So pick a few holes in ti as per normal.
To be shot down in flames?
- Thread starter Croxden
- Start date
These were discussed at great length in a thread back in October 2010 and the idea was generally thought to be crackpot. That's still my view, I can't see a small motor and tiny battery within a pedal doing anything really useful, and charging at two points will entail much faffing about low down.
Here's the link to that thread.
Here's the link to that thread.
this story runs and runs.
http://companycheck.co.uk/company/07296768/BRITT-TECHNOLOGIES-LIMITED/financial-accounts
I guess he must have burned more than £100k. I wish him luck but I fear he'll simply burn all his savings in pursuit of this unpractical idea.
We discussed it back in 2011. The idea is simple enough: why don't we put a motor in each pedal? no messy wiring! However, the ride would be unpleasant because the motor needs the weight of your legs to give it purchase, pushing against the sole of your shoes as it turns. Not only that, I did some calculations and came up with 10W maximal possible power per pedal.
Would you buy an electric bike if it can only offer that much power?
http://companycheck.co.uk/company/07296768/BRITT-TECHNOLOGIES-LIMITED/financial-accounts
I guess he must have burned more than £100k. I wish him luck but I fear he'll simply burn all his savings in pursuit of this unpractical idea.
We discussed it back in 2011. The idea is simple enough: why don't we put a motor in each pedal? no messy wiring! However, the ride would be unpleasant because the motor needs the weight of your legs to give it purchase, pushing against the sole of your shoes as it turns. Not only that, I did some calculations and came up with 10W maximal possible power per pedal.
Would you buy an electric bike if it can only offer that much power?
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it was posted on the news thread back in 2011. The motor can only produce most useful work when the height of the legs does not change, the crank arm position is at vertical. Assuming a cadence of 100 RPM, the power of the motor is torque * 0.5 * 3.14 * 2 * 100 /60 = 5.2 * T (Watts, T in NM)
The torque varies with the angle of the crank arm, the simplest way to calculate this is to use excel to compute the average. I calculated that the average was about 2NM.
As a simple test, Use a spanner and try to turn the pedal while someone sits on the bike, pushes down on the pedal and squeezes the brakes. The small width of the pedal does not help Steve's idea.
Another way to calculate or estimate this is to use the ratio between the crank arm length c and half the pedal width p. Maximum motor power = human power * p / (c+p) that is roughly 100W * 0.07/(0.175 + 0.07) = 28W (14W per motor) before taking into account reduction in torque due to the crank arm angle.
The torque varies with the angle of the crank arm, the simplest way to calculate this is to use excel to compute the average. I calculated that the average was about 2NM.
As a simple test, Use a spanner and try to turn the pedal while someone sits on the bike, pushes down on the pedal and squeezes the brakes. The small width of the pedal does not help Steve's idea.
Another way to calculate or estimate this is to use the ratio between the crank arm length c and half the pedal width p. Maximum motor power = human power * p / (c+p) that is roughly 100W * 0.07/(0.175 + 0.07) = 28W (14W per motor) before taking into account reduction in torque due to the crank arm angle.
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When the crank reaches the top or the bottom, the motor helps pushing the chain ring round. I calculated the maximum useable torque is half pedal width * half rider weight * g = 0.07 * 38 * 9.98 * sin(a)^2 then average over 0 to pi()/2 (a being the angle of the crank arm to vertical). The motor is assumed to be perfect (it's for the inventor's benefit). The power of the motor is limited by the rider.
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I think I screwed up somewhere in my maths. A wider pedal is more comfortable to the rider but should not change anything in the average work produced by the motor pedals. I tried to remember what the maths was but not quite succeded. Regarding full rider weight, both feet must remain on the pedals for both motors to work at the same time, if you put more on one foot, the weight on the other is reduced, the total is the same.
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I think it might be 30 watts or just reach 50 watts per pedal. But of course as I've observed previously, only one pedal is acting at a time (pressure sensors) so the power isn't the sum of the two as Stephen Britt has tried to claim.
Whatever it is, it is hopelessly inadequate. Our e-bikes produce over 300 watts minimum, and those at that lowest level many find very inadequate. In the earliest days of e-bikes being attempted, they strictly complied with the 200 watts maximum law at that time. That is why they failed, it took two more decades and manufacturer pragmatism to get them accepted by using at least double the legal power limit.
I think the comment from Russ after trying the pedals sums it up, "I could detect the difference". We need more than that when faced with a hill.
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Whatever it is, it is hopelessly inadequate. Our e-bikes produce over 300 watts minimum, and those at that lowest level many find very inadequate. In the earliest days of e-bikes being attempted, they strictly complied with the 200 watts maximum law at that time. That is why they failed, it took two more decades and manufacturer pragmatism to get them accepted by using at least double the legal power limit.
I think the comment from Russ after trying the pedals sums it up, "I could detect the difference". We need more than that when faced with a hill.
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