Power input of the rider

[HB129]

Hi!

New member here. I've seen across various bike manufacturers, that in the description of the shimano system the display is capable of showing "power input of rider in watts". The same exact phrasing is used on different manufacturers, so i guess it's an official description. Any info on how to access this data?
Thanks

 

[Travelly]

Within the mission control app you need to use the 'fake' channel, as they call it, to send the data to your preferred device for display. Garmin, Wahoo etc.

 

[Kiwi in Wales]

Hi!

New member here. I've seen across various bike manufacturers, that in the description of the shimano system the display is capable of showing "power input of rider in watts". The same exact phrasing is used on different manufacturers, so i guess it's an official description. Any info on how to access this data?
Thanks

It's a shame the Blevo App does not work with your Shimano system.
The first screen shot is the live capture and the second screen shot is displyed during and after the ride.

 

[Gary]

"power input of rider in watts"

Anybody know if this even vaguely accurate?
Seems unlikely with the cost of stand alone power meters

 

[HB129]

Within the mission control app you need to use the 'fake' channel, as they call it, to send the data to your preferred device for display. Garmin, Wahoo etc.

Unfortunately i'm on a shimano system so mission control is not an option.

 

[HB129]

It's a shame the Blevo App does not work with your Shimano system.
The first screen shot is the live capture and the second screen shot is displyed during and after the ride.

View attachment 7354

View attachment 7355

nice app!

 

[HB129]

Anybody know if this even vaguely accurate?
Seems unlikely with the cost of stand alone power meters

My ultimate goal is to get the power reading to a garmin, to get a better estimate on effort made during a ride.

 

[Gary]

I don't really think data/stat collecting/nerding on an Ebike would be of a lot of value except for maybe if your goal is staying in low training zones..
I just go on percieved effort on mine and I've never ever got anywhere even close to non-Ebike efforts.

 

[Kiwi in Wales]

Anybody know if this even vaguely accurate?
Seems unlikely with the cost of stand alone power meters

The Brose motors have a built in power meter which appears to be fairly accurate

 

[mark.ai]

I haven't seen any way to display a value for the current rider power (or motor assist power) for the Shimano motors either. The only thing seems to be the power assist bar which goes along the bottom of the screen and up the right hand side.

You'd think it should be possible as they must use some value in the software running on the bike in order to determine the assist level. Maybe they will add it to the variables you can read wirelessly on a Garmin etc one day.

 

[HB129]

I don't really think data/stat collecting/nerding on an Ebike would be of a lot of value except for maybe if your goal is staying in low training zones..
I just go on percieved effort on mine and I've never ever got anywhere even close to non-Ebike efforts.

On my brief experience with ebikes, riding trails up the mountain resembles flat road riding, where a relatively high cadence is key. Riding with other ebikers gets a pretty decent workout if the pace is high.

 

[Gary]

The Brose motors have a built in power meter which appears to be fairly accurate

Thanks Kiwi. Got a link to any info to back that up anywhere online?

 

[Kiwi in Wales]

Thanks Kiwi. Got a link to any info to back that up anywhere online?

Hi G, not quite sure what you mean dude, To back what up? The accuracy of the power meter?
If yes, then..... no, apart from the below which like I said looks 'fairly' accurate.

 

[Gary]

Yeah. Sorry. I meant any sort of info to back up the accuracy of the brose built in power meter readings.
The above table shows nothing pertaining to it's accuracy at all really. is it from a ride you did?
and is it from a levo?

 

[Kiwi in Wales]

Yes and yes.
As I said in the posts above all captured on Blevo
When I said fairly accurate, I have used a Stages power meter before and the output was very similar. So I was comparing to that.
How accurate is a Stages meter? I do not know ☹
Hopefully, we have some roady dudes with more power meters than a power meter factory on the forum that could comment? ?

 

[Gary]

When I said fairly accurate, I have used a Stages power meter before and the output was very similar. So I was comparing to that.

I'm confused as hell now

How can power readings from an assisted system be comparable to power meter readings from non assisted roadbike's powermeter?

Oh... and stages are supposedly fairly accurate unless you have a massive difference in power from one leg (as it's a single sided system).

I also can't get my head round how any of the power data from Blevo could be useful from a training aspect.

 

[100 Cols]

I'm confused as hell now

How can power readings from an assisted system be comparable to power meter readings from non assisted roadbike's powermeter?

I also can't get my head round how any of the power data from Blevo could be useful from a training aspect.

IF Blevo only shows average and max power of the rider during a ride (like in screenshot), the usefulness of that info is questionable, but IF the rider power info would be available as real time data, using same ANT+ power meter profile as any other separate power meter, then THAT would totally replace a separate power meter. I don't understand why manufacturers don't do that.

The numbers in this screenshot are somewhat interesting, as rider input in ECO and TRAIL is lower than in TURBO... isn't it "normally" the opposite - you push all out of your legs until they explode, then switch to TURBO/BOOST and try to recover. I would expect that TURBO shows lower RIDER Watts than ECO. At least in my riding style it certainly would?!?

 

[mark.ai]

I'm guessing @JanCapek could add a power graph for each ride to his Ebike Field Garmin App for Turbo Levo if he wanted - since he has already added graphs for Battery State and Assist Mode.

I'd love to be able to get the power values for Shimano too ...

 

[Gary]

IF Blevo only shows average and max power of the rider during a ride (like in screenshot), the usefulness of that info is questionable, but IF the rider power info would be available as real time data, using same ANT+ power meter profile as any other separate power meter, then THAT would totally replace a separate power meter. I don't understand why manufacturer's don't do that.

My guess is because the data isn't actually accurate. There;s no way Brose'd put something as accurate as a proper stand alone power meter in a mass produced motor system where 99%+ of the users won't even understand how to use power to train by

View attachment 7455

The numbers in this screenshot are somewhat interesting, as rider input in ECO and TRAIL is lower than in TURBO... isn't it "normally" the opposite - you push all out of your legs until they explode, then switch to TURBO/BOOST and try to recover. I would expect that TURBO shows lower RIDER Watts than ECO. At least in my riding style it certainly would?!?

I thought the same until I realised if eco is only used on the flat and downhill soft pedalling is all that's ever required to ride at normal mtb speeds. (an average power of 90w really is nothing for any reasonably fit cyclist) Whereas if Boost/turbo is only ever used up the steepest hills more effort will be required. Going with this theory it looks like trail is probably being used mainly for shallow inclines or slightly fastee speeds on the flat.
Just goes to show we don't all use the modes in the same way.

 

[JanCapek]

Hi, I think there are lots of wrong assumptions here.
Yes, Specialized bikes output real-time data of both rider power and motor power. According to all available tests they seems to be quite accurate (apart from random spikes) and even Specialized mention rider power reading as accurate "with same precision or better than current power meters on market".
I don't see why this can't be used for training as with power meters on non-ebikes. Its the same thing, you just have additional motor power to increase your speed (if you want). The truth is that because I wanted to ride with power meter was just another reason to buy Levo as it just already have this sensor included in package.

I don't need to add anything related to this to Ebike Field, as Rider power data are available as standard ANT+ power sensor, so Garmin can connect to this sensor and draw power graph alone (higher device models). I only added possibility to choose to show rider power value on Ebike Field - Nerd Style.

But this discussion is about Shimano motors and I don't think they support ANT+ connectivity at all, so no data for Garmin devices if I have correct info. It is shame really that only Specialized have ANT+ connectivity in their bikes. I will be more than happy to know that something is changed there.

 

[Gary]

even Specialized mention rider power reading as accurate "with same precision or better than current power meters on market".

Ok. so if this is true I'd be very interested to find out exactly how the riders' power is measured.
What I mean by this is what mechanical device does the brose motor use to measure the human forces exerted through the cranks?

 

[steve_sordy]

I still can't get my head round post #3 "Average motor power 449W".

If the motor is supposed to be restricted to an average of 250W, does that imply the motor of "Kiwi in Wales" has been de-restricted? I'm not being critical, just trying to understand all this stuff.

 

[mark.ai]

Ok. so if this is true I'd be very interested to find out exactly how the riders' power is measured.
What I mean by this is what mechanical device does the brose motor use to measure the human forces exerted through the cranks?

I'd be interested to know too - I can't find any real details for Brose motors with online searches though. But I have come across some general info which I'll link below for those interested in reading. Whether any of the current motors use these methods I don't know

Electric Assist Bicycle Basics | About Pedal Assist | The New Wheel - different sorts of e-bike assistance. So torque sensors can be used to measure rider power input.

X-CELL RT 2.0Suitable for pedelecs and e-bikes - Thun.de - the Thun X-Cell torque sensors seem to be popular for torque sensing in e-bike conversion kits.

How Torque Measurement Transducers Work | SensorData Technologies, Inc. - a slightly more technical explanation of torque measurement transducers.

how sensors work - torque transducers - if you made it to this link you win a prize!! Detailed explanation of a torque transducer. I guess this is one particular type/method and others also exist.

TLDR: you can have a torque sensor on a rotating shaft with no physical connection to the outer casing - seems like magic to me ...

 

[mark.ai]

I still can't get my head round post #3 "Average motor power 449W".

If the motor is supposed to be restricted to an average of 250W, does that imply the motor of "Kiwi in Wales" has been de-restricted? I'm not being critical, just trying to understand all this stuff.

Yep it doesn't seem right does it And even a de-restricted motor wouldn't affect the power output of the motor - it only means that the motor can keep applying the same power above the normal cut-off speed limit.

So the motors are supposed to have up to "250W continuous power rating" - but no-one seems to be able to find a definition for what that exactly means! Over what sort of time do they have to average 250W - 1 hour? 2 hours? Over the duration of the battery? (Which should be 2 hours with a 500W battery).

The only explanation for post #3 above is that the duration of the measurement was shorter than that required to average 250W. So maybe if the rider had kept going in turbo it would have gradually decreased the power it was supplying at some point.

 

[mark.ai]

Ok found a bit more info with some BING-fu - the power rating test seems to be defined in European standard EN 15194. I found a copy online here: http://www.bikeebike.com/uploads/1/2/6/8/12686946/norme_en_15194.pdf

So it seems the power can be measured at the motor or at the wheel, and there seems to be a bit of flexibility in the test. But the full motor shaft test is detailed in EN 60034-1 and I can't find a free copy of that yet … (Edit 2004 version: http://nostopmotor.com/Uploads/file/20160715/20160715112700_4090.pdf)

The relevant parts of the text seem to be:

4.2.7 Maximum power measurement​

​

4.2.7.1 Measurement at the engine shaft​

​

The maximum continuous rated power shall be measured according to EN 60034-1 when the motor reaches its thermal equilibrium as specified by the manufacturer.​

​

NOTE Thermal equilibrium: temperatures of motor parts do not vary more than 2K per hour.​

​

In circumstance where the power is measured directly at the shaft of the electronic motor, the result of the measurement shall be decreased by 1,10 to consider the measurement uncertainty and then by 1,05 to include for example the transmission losses, unless the real values of these losses are determined.​

​

4.2.7.2 Alternative method​

​

When the power is measured at the wheel, the result of the measurement is the reading value.​

And then the alternative method is defined as:

Maximum power measurement - Alternative method​

​

D.1 Generalities​

​

This Annex gives guidance on how to measure the power at the wheel.​

​

The maximum power which the bicycle gives assistance may differ by ± 5% of the power indicated on the label described in Clause 5. During a production conformity check, the maximum speed may differ by ± 10% from the above-mentioned determined value. The test shall be performed without pedalling using only the electrical assistance system (the test bicycle shall be prepared accordingly).​

​

D.2 Test conditions​

​

a) The test may be performed either on a test track, a test bench or on a stand that keeps the motor driven wheel free of the ground.​

b) The speed-measuring device should have the following characteristics:​

 Accuracy: ± 2%​

 Resolution: 0,1 km/h​

c) The ambient temperature should be between 5 °C and 35 °C.​

d) Maximum wind speed: 3 m/s.​

e) The battery should be fully charged according to the manufacturer's instructions.​

f) The test should be performed with mass of the test bicycle equal to 150 kg.​

​

D.3 Test procedure​

​

Any appropriate method for checking for this requirement is acceptable.​

​

a) Pre-condition the EPAC by running it for 5 min at 80% of the maximum assistance speed as declared by the manufacturer.​

b) Stop the bicycle.​

c) Note the time between the action start and the EPAC to travel 20 meters.​

d) Verify the speed value is equal or less than the maximum speed declared by the manufacturer after 20 metres (D).​

e) Verify the maximum continuous rated power at wheel is: P = m x 2 x D^2 / T^3 with the time T which is the noted value in c).​

​

NOTE Considering that on a test track, the engine temperature is not stable, and the grip of the tyre on the road can be variable, the result of the measurement should be decreased by 1,10 to consider the measurement uncertainty. The measure is compared to the limit given in the scope of this European Standard.​

 

[mark.ai]

I don't need to add anything related to this to Ebike Field, as Rider power data are available as standard ANT+ power sensor, so Garmin can connect to this sensor and draw power graph alone (higher device models). I only added possibility to choose to show rider power value on Ebike Field - Nerd Style.

But this discussion is about Shimano motors and I don't think they support ANT+ connectivity at all, so no data for Garmin devices if I have correct info. It is shame really that only Specialized have ANT+ connectivity in their bikes. I will be more than happy to know that something is changed there.

Thanks for the info @JanCapek

As for Shimano motors, currently there is only ANT+ / Bluetooth connectivity using Shimano D-Fly for Di2 - e.g. you can read Di2 gear position and battery percentage. But soon there is a new device EW-EN100 which can also be connected to external devices via ANT+ or Bluetooth LE. It's unclear what information you will be able to get though - there has been mention of speed, battery, assist mode, cadence, but no mention of power yet.

 

[JanCapek]

But soon there is a new device EW-EN100 which can also be connected to external devices via ANT+ or Bluetooth LE.

Interesting! I would love if somebody will test my apps with this device for compatibility. But that "ANT private" in specification sounds a little pessimistic, so I hope Shimano didn't closed connectivity only to their devices..

 

[Gary]

I'd be interested to know too - I can't find any real details for Brose motors with online searches though. But I have come across some general info which I'll link below for those interested in reading....
TLDR: you can have a torque sensor on a rotating shaft with no physical connection to the outer casing - seems like magic to me ...

Without reading any of th links. (it's Saturday night. forgive me, eh?) is a torque sensor even the same thing as a power METER? (Yes I realise power meters measure torque)
The dictionary definition of a sensor is not the same as a meter

 

[khorn]

Any type of measuring effect comes from torque, the calculation is quite simple as a matter of fact.

Karsten

 

[khorn]

Many ordinary power meters on road bikes(Stages, Pioneer etc) use string gates that measures the amount of flex in the crank arms by the torque that the rider put into the pedals - I have a few myself and its quite accurate.

Karsten