Why not the choice of speed sensors on centrl crank motors?

[Bigbee]

I was bored yesterday,so I was trawlingthe web.Crank motors intrigue me,Ive had a couple of goes and didnt like them much.Panasonic and Yamaha( thats about it isnt it?) both have torque sensors.Why dont they have the option of speed sensors?I believe Powabykes front hub is a speed sensor with no option of torque sensor?So its the other way around.

So learned ones ,please.........


Why dont the central crank co's have speed sensors?
Why dont Powabyke have torque sensors?

Whats the real difference between torque and speed sensors?

thanks!

 

[Fecn]

Why dont the central crank co's have speed sensors?
Why dont Powabyke have torque sensors?

Whats the real difference between torque and speed sensors?

I don't know the details of the Sanyo system, but the Panasonic system does detect both torque and speed - However, the speed that it is measuring is motor speed (and hence chain speed) rather than bike speed. If you have known gear ratios, then it's an effective enough way of measuring the road speed to determine the cutoff speed, and eliminates the need for extra sensors outside of the main crank unit - This keeps the unit compact and reduces the likelyhood of faults due to dodgy wiring etc.

Torque is how hard you're pressing on the pedals. - The panasonic system uses this to work out how much juice to supply to the motor.

Speed is how fast you're making them go round (or how fast the bike is going). - Panasonic system uses this to work out when to reduce the juice going to the motor in order to comply with legal restrictions. By changing the gearing setup, they can use the same unit to meet the requirements for various countries.

 

[flecc]

As Fecn says, the Panasonic system does sense speed, but it can only relate to a road speed if te usrer keeps the bike's rear sprocket and gearing system standard as the manufacturer designed it.

The sensing method on the earlier unit was by a ring of magnets on the internal final drive gear to the output chain sprocket, the pass rate of the magnets sensed by a Hall sensor. The latest unit has abandoned that method and now derives it's speed sensing from the pulse rate of the motor's Hall sensors.

Since the Yamaha is clearly a copy of the general features of the Panasonic system, that will doubtless also have internal speed sensing. The Japanese Sunstar kit is similar and to get a normal bike to have the same features, it incorporates a new torque sensing bottom bracket spindle and chainwheel which replace the bike's original ones. The kit is shown below and is avalailable from a French company:

Some early Chinese hub motors had built in torque sensors but they were a source of trouble and have largely disappeared.
.

 

[Sir_Bob]

how do i get it back

 

[Sir_Bob]

sorry lost my last one.
Tennant super is on offer tonite

 

[daniel.weck]

The Japanese Sunstar kit is similar and to get a normal bike to have the same features, it incorporates a new torque sensing bottom bracket spindle and chainwheel which replace the bike's original ones. The kit is shown below and is avalailable from a French company:

.

The Sunstar S02 kit costs around 1300 Euros...not cheap !

Japanese home page: ƒTƒ“ƒXƒ^[‹ZŒ¤ SUNSTAR ENGINEERING INC. | “d“®ƒAƒVƒXƒgƒ†ƒjƒbƒgEŽ©“]ŽÔ

Click these links for high-resolution brochures:

http://daniel.weck.free.fr/Sunstar1.jpg
http://daniel.weck.free.fr/Sunstar2.jpg

http://www.greenspeed.com.au/sunstar.jpg

Unlike the S01, it's a brushless motor. Its peak power is 330W instead of 235W, and it only weighs 2.9Kg instead of 4.4kg.

The S01 is apparently still available:

Acheter

 

[daniel.weck]

Look at the bulk of the Sunstar S01 motor:

Yet it fits nicely on a small folding bike:

VELO ELECTRIQUE PLIANT SUNSTAR NEUF on eBay (end time 22-Oct-09 12:40:57 BST)

Europe retailer:

Le premier service de location courte et longue durée de Vélo - Tricycle - Triporteur - Scooter électrique sur Rhône Alpes

cyclable - velo de ville, vélo hollandais, vtc, bicyclette - Dijon - Toulouse - Lyon - Paris

 

[PaulC]

My ancient (2002) Merida Powercycle (which I suspect had a Yamaha crank unit) had a torque sensor and a speed sensor.
The speed sensor worked off the number of pedal revolutions - to quote the manual, "power assistance will cutoff at a pedal rate of 63 rpm".
This was OK on hills but dangerous when trying to go quickly through an intersection.
Paul

 

[daniel.weck]

Compare with the S02 in-situ:

 

[Dynamic Position]

With the availability of technology e-bike controllers could be designed incorporating a Sirfstar III GPS chip. E-bikes could then be used anywhere legally with the bike assist speed limited to suit national e-bike road speed limitations and deresticted when being used on off road. The technology could also be used for other functions useful to e-cyclists.

 

[Fecn]

With the availability of technology e-bike controllers could be designed incorporating a Sirfstar III GPS chip. E-bikes could then be used anywhere legally with the bike assist speed limited to suit national e-bike road speed limitations and deresticted when being used on off road. The technology could also be used for other functions useful to e-cyclists.

Unfortunately off-road doesn't really mean off-road. E-Roads (which are roads without any tarmac surface) are still covered by the Highways act. In fact, I believe that any route to which the public can gain access falls under the remit of the highways act as a UCR (Unclassified Road). UCRs include things such as sheep tracks across fields... or muddy paths through the woods. I think that the only place you can truly go legally 'off-road' is on private land.

Please note that although you can drive your 6-litre 3-tonne 4x4 down a mud track, that vehicle is still a road-legal vehicle on a public highway. A 16mph+ e-bike on the same dirt track would still be against the law (alhough admittedly, the likelyhood of meeting a policeman with a radar gun i pretty much nil)

 

[Mussels]

With the availability of technology e-bike controllers could be designed incorporating a Sirfstar III GPS chip. E-bikes could then be used anywhere legally with the bike assist speed limited to suit national e-bike road speed limitations and deresticted when being used on off road. The technology could also be used for other functions useful to e-cyclists.

Publicly available technology isn't that good yet, it isn't cheap and I'd just wrap it in tinfoil.

A 16mph+ e-bike on the same dirt track would still be against the law (alhough admittedly, the likelyhood of meeting a policeman with a radar gun i pretty much nil)

Cyclists on Bournemouth beach thought that too until recently.

 

[Straylight]

With the availability of technology e-bike controllers could be designed incorporating a Sirfstar III GPS chip. E-bikes could then be used anywhere legally with the bike assist speed limited to suit national e-bike road speed limitations and deresticted when being used on off road. The technology could also be used for other functions useful to e-cyclists.

And why not extend this to cars, people would still have all their beloved POWER available, just not beyond the speed limit

 

[dan]

Unfortunately off-road doesn't really mean off-road. E-Roads (which are roads without any tarmac surface) are still covered by the Highways act. In fact, I believe that any route to which the public can gain access falls under the remit of the highways act as a UCR (Unclassified Road). UCRs include things such as sheep tracks across fields... or muddy paths through the woods. I think that the only place you can truly go legally 'off-road' is on private land.

Please note that although you can drive your 6-litre 3-tonne 4x4 down a mud track, that vehicle is still a road-legal vehicle on a public highway. A 16mph+ e-bike on the same dirt track would still be against the law (alhough admittedly, the likelyhood of meeting a policeman with a radar gun i pretty much nil)

vehicle excise and registration act..states a public road is defined as "a road that is repairable at the public's expense and includes pavements and grass verges".

 

[Mussels]

vehicle excise and registration act..states a public road is defined as "a road that is repairable at the public's expense and includes pavements and grass verges".

Traffic wardens pretty much consider a public road to be anywhere the public can walk without climbing over a fence, ask any motorcyclist who parks in London regularly. They got to that conclusion over a long time and much opposition and I expect the Police would take the same stance.

 

[Dynamic Position]

Unfortunately off-road doesn't really mean off-road. E-Roads (which are roads without any tarmac surface) are still covered by the Highways act. In fact, I believe that any route to which the public can gain access falls under the remit of the highways act as a UCR (Unclassified Road). UCRs include things such as sheep tracks across fields... or muddy paths through the woods. I think that the only place you can truly go legally 'off-road' is on private land.

Please note that although you can drive your 6-litre 3-tonne 4x4 down a mud track, that vehicle is still a road-legal vehicle on a public highway. A 16mph+ e-bike on the same dirt track would still be against the law (alhough admittedly, the likelyhood of meeting a policeman with a radar gun i pretty much nil)

This definition would make it simpler/cheaper to limit assisted bike speed to 15mph. The publicly available technology is more than capable of providing this simple function as a back up to existing speed measurement which would still be needed while cycling through tunnels etc when GPS signals are lost.

 

[Mussels]

This definition would make it simpler/cheaper to limit assisted bike speed to 15mph. The publicly available technology is more than capable of providing this simple function as a back up to existing speed measurement which would still be needed while cycling through tunnels etc when GPS signals are lost.

What about when a minor road runs right next to a dual carriageway? GPS isn't accurate enough to get it right all the time.

 

[Straylight]

For this path to work, the unit would need a map to put the GPS coordinates in context. Such a map would then require a means of update. All of which would vastly increase the cost of the controller.

My statement earlier, while being somewhat tongue in cheek, was meant to provoke the question of wether a licence/insurance etc. increases reposibility in the individual. I'd contend not, so I ask why the disparity? Either all vehicles require physical speed restriction, or none. I am however in favour of power restriction by class of vehicle, to prevent people building what are effectively unregistered electric motorbikes. The choice then becomes between speed and torque, based on the motor you buy, and the wheel you put it in.

Back ON Topic, I think that the more the market matures and grows, the more choices become available to suit personal taste.

 

[Erik]

Look at the bulk of the Sunstar S01 motor:

Yet it fits nicely on a small folding bike:

VELO ELECTRIQUE PLIANT SUNSTAR NEUF on eBay (end time 22-Oct-09 12:40:57 BST)

For a moment I thought that this little folder was with the new S02 motor, but alas it's the old S01.

If it had been the S02 you could build a better Dahon Boost for less money than Dahon wants.

€999 for the bike with motor and €499 for a good Dahon folder versus €2000 for a not-yet-available Dahon Boost

 

[Dynamic Position]

For this path to work, the unit would need a map to put the GPS coordinates in context. Such a map would then require a means of update. All of which would vastly increase the cost of the controller.

My statement earlier, while being somewhat tongue in cheek, was meant to provoke the question of wether a licence/insurance etc. increases reposibility in the individual. I'd contend not, so I ask why the disparity? Either all vehicles require physical speed restriction, or none. I am however in favour of power restriction by class of vehicle, to prevent people building what are effectively unregistered electric motorbikes. The choice then becomes between speed and torque, based on the motor you buy, and the wheel you put it in.

Back ON Topic, I think that the more the market matures and grows, the more choices become available to suit personal taste.

A rough map is probably necessary for context, though the usual details would not be required as the speed could be calculated from distance/time. It is irrelevant if a side road is running parallel with a dual carriage way because the assisted speed would be limited to 15mph. The law ought to concentrate on dealing with those who drive/ride/cycle irresponsibly rather than try and outlaw those who don't.