Really like look of these and would like to try one. Anybody any feedback or first hand knowledge.
Bultaco Brinco
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Yes I noticed that and thought it strange. I,d be interested to know where exactly the torque measurements are taken. Both figures are absurdly high for electric motors and suspect figures are well down drive train ??? Folk tend to forget torque available at back wheel is multiplied by overall gear reduction , there does not seem to be an industry standard for ebike quoted torque figures. In cars its flywheel, in motorbikes its either crank or just post primary reduction,but there is confusion even in that one..??
No way on earth a 250 w motor can produce 60nm torque at spindle.??
Somebody must know where figures come from but never seen it mentioned.
Just for interest.. An old 903cc fireblade produced ( if my memory is correct) about 40 ftlb torque. 60 nm is 44 ftlb. So claim is yam 250w electric motor is producing more torque than an old Honda Fireblade. Quoting torque without saying where is pretty meaningless.
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Yes, a standardised way of measuring an electric bikes torque figure would make comparisons easier and more relevant.
So claim is yam 250w electric motor is producing more torque than an old Honda Fireblade..[/QUOTE]
It might be. Most ebike motors can pull away from rest without slipping a clutch (which they don't have). Can a Fireblade? Of course the Fireblade has vastly more power, but torque and power are not the same thing.
It might be. Most ebike motors can pull away from rest without slipping a clutch (which they don't have). Can a Fireblade? Of course the Fireblade has vastly more power, but torque and power are not the same thing.
It's said that the Bosch torque figure is at the chainwheel output, which is geared well down from the motor rpm. It's probably the same for the Yamaha and most other crank units.
The only one I've seen quoting differently is Tonaro, quoting 125 Nm for their crank unit bikes, that's measured at the rear wheel in the lowest derailleur gear. Thay are good climbers, able to slog up hills on throttle alone at moderate speeds.
Also, in this respect it's important to remember the 250 watts rating is nominal, some legal motors are capable of well over twice that in net power.
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Yes, it was the agents, Powerpedals, quoting that figure.
Seems the Tonaro torque is very similar to the Bosch and Yamaha units.
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It might be. Most ebike motors can pull away from rest without slipping a clutch (which they don't have). Can a Fireblade? Of course the Fireblade has vastly more power, but torque and power are not the same thing.[/QUOTE]
Electric motors are capable of producing torque from zero revs,ICE engines cant so need a clutch.
No a 250w motor can never produce anything like 60nm. The torque is measured after lots of gear reduction. ( a 10 to 1 reduction would multiply torque by 10, but reduce rpm by a factor of 10, power produced is not effected)
Because the torque for mid drive motors is taken at the chain ring, which is subject to the maximum reduction/ minimum rotational speed.( therafter the torque would decrease, ie back wheel spins quicker than chain ring)
Just google electrical motors and look at their torque curves.( shaft power / torque)
Just looked up some figures..a 1hp (750 w) best performing I could find produced from 14 nm at 1000rpm, reducing to 4 nm at max shaft speed. ( in this case 4000 rpm) DC electric motors generally produce best torque at low rpm. Pedelec motors are 250 w and will give max torrque low rpm.
If you geared fireblade in similar fashion (I,d guess around 35 to one reduction) you'd get in order of 1500 nm !!!
Other angle to come at is from cadence of riders with respect to rpm of electric motors .(dc ?don't think controllers have inverters built in but ???)
My max cadence is 105. My optimum for relaxed pedalling is around 70 ? Electric motors rpm range for torque 0 to 4000 rpm? Roughly. Assuming bike designed to be at max rpm at max cadence..so 4000 rpm would equate to 80 crank rpm ( ??)
That's a reduction of 50 to 1.
With a max torque figure of 80nm motor would only have to supply 80/50 nm..plus a bit for frictional losses...That gives a motor torque figure of around 2 nm..at max cadence rate..( assumed 80) That's inline with figures quoted from 750 W motor.
Yes there will be errors with motor max rpm, etc but estimate of correct order. Ie reduction from motor to crank between 30 to 50 to 1. ( for Yam, the Bosch is different its chain ring spins 2.5 faster than crank,hence smaller to regain torque/ gearing and with a smaller overall reduction, ( to chain ring) hence slightly more efficient to chain ring.( and interestingly its torque figure in theory would be well under yams ??!!)
As ab earlier poster stated qouting torque without knowing where and in what gear is really meaningless.
Ps
Your calc is perfectly valid but its taking torque at chain ring ( not motor) and power transmitted through system. Fine. Proves nothing about torque produced by the motor.( at its shaft)
Repeat calc with shaft speed of 3000 rpm or so , with same power transmitted and the torque figure will be lower by factor of reduction between chain ring and motor..
Calc automatically compensates.
A 250w motor in a pedelec supplies around 4 nm..gearing does the rest.
Just google electrical motors and look at their torque curves.( shaft power / torque)
Just looked up some figures..a 1hp (750 w) best performing I could find produced from 14 nm at 1000rpm, reducing to 4 nm at max shaft speed. ( in this case 4000 rpm) DC electric motors generally produce best torque at low rpm. Pedelec motors are 250 w and will give max torrque low rpm.
If you geared fireblade in similar fashion (I,d guess around 35 to one reduction) you'd get in order of 1500 nm !!!
Other angle to come at is from cadence of riders with respect to rpm of electric motors .(dc ?don't think controllers have inverters built in but ???)
My max cadence is 105. My optimum for relaxed pedalling is around 70 ? Electric motors rpm range for torque 0 to 4000 rpm? Roughly. Assuming bike designed to be at max rpm at max cadence..so 4000 rpm would equate to 80 crank rpm ( ??)
That's a reduction of 50 to 1.
With a max torque figure of 80nm motor would only have to supply 80/50 nm..plus a bit for frictional losses...That gives a motor torque figure of around 2 nm..at max cadence rate..( assumed 80) That's inline with figures quoted from 750 W motor.
Yes there will be errors with motor max rpm, etc but estimate of correct order. Ie reduction from motor to crank between 30 to 50 to 1. ( for Yam, the Bosch is different its chain ring spins 2.5 faster than crank,hence smaller to regain torque/ gearing and with a smaller overall reduction, ( to chain ring) hence slightly more efficient to chain ring.( and interestingly its torque figure in theory would be well under yams ??!!)
As ab earlier poster stated qouting torque without knowing where and in what gear is really meaningless.
Ps
Your calc is perfectly valid but its taking torque at chain ring ( not motor) and power transmitted through system. Fine. Proves nothing about torque produced by the motor.( at its shaft)
Repeat calc with shaft speed of 3000 rpm or so , with same power transmitted and the torque figure will be lower by factor of reduction between chain ring and motor..
Calc automatically compensates.
A 250w motor in a pedelec supplies around 4 nm..gearing does the rest.
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So am I wrong in presuming the post was about:
http://www.edmondson-racing.co.uk/prods/bultaco-brinco-new.html
This is 2kw, not 250w?
http://www.edmondson-racing.co.uk/prods/bultaco-brinco-new.html
This is 2kw, not 250w?
the motor is a 2kw direct drive. It has a 15mph mode but is illegal on public roads.
I don't know how true their slogan 'Rock your day' is, 2kw is usually not enough for 38mph, but you can easily experience 38mph with any bike going slightly downhill.
I don't know how true their slogan 'Rock your day' is, 2kw is usually not enough for 38mph, but you can easily experience 38mph with any bike going slightly downhill.
I agree, cant see 2kw ( under 3bhp) getting to 38 mph..but my little enduro bike ( a 125 four stroke/ around 11bhp but 110kg) rarely ( never) gets over 20 mph on trails..
Not sure Brinco would cope with climb where I use 125 tho...its a long steep one. ( uphill 40 mins or so!!) hence questions...
Not sure Brinco would cope with climb where I use 125 tho...its a long steep one. ( uphill 40 mins or so!!) hence questions...
I would also like to learn more about the bike. Although the first batch was off road only, I understand a road legal version is on it's way.
Found this test http://www.mirror.co.uk/lifestyle/motoring/bultaco-brinco-reviewed-switched-spanish-6581401
Found this test http://www.mirror.co.uk/lifestyle/motoring/bultaco-brinco-reviewed-switched-spanish-6581401