Speed vs battery life

[Stefan Mikes]

Is the watts data just the pedaling energy while the kcal data includes pedaling energy plus resting energy used?

The power as reported by Strava is taken from your e-bike power-meter while kcal is what you have actually input into pedalling (but not the energy you need to sustain your life -- it is not metered).

Yesterday, I was pedalling my Vado SL at very low assistance (24% average assistance is what 12% assistance would be on my full-power Vado 6.0).

Meanwhile, BLEvo reported:

As you can see, BLEvo uses a different algorithm for kcal. It is, however, important that BLEvo (only working for pre-Mastermind e-bikes) gives you precise figures for average assistance, battery consumption, Wh per km or mile, the rider's energy input (net) and the battery contribution into the ride. With more data (BLEvo produces tons of stats!), I learned my average leg power was 94 W, not 73 as Strava determined. BLEvo also told my my maximum leg power (in burst) was 316 W.

 

[Tbill]

I was looking at my speed with zero assist or with it set at "1" and I seemed to be going around 12 miles an hour.
I think that would be a decent speed to go to get throttle only range while not taking an unusually long time.

 

[mschwett]

Just put the free version of Strava on my phone, very interesting seeing the graphs of elevation, speed and cadence. Thanks for the suggestion.

Did substantially the same test loop yesterday at my normal riding style - mostly ECO but SPORT or even TURBO going up hills. Coasting down hills.

Here's the comparison:
........................................................................Mission
........................................................................Control......Strava.....Strava
Distance....Avg Speed.....Time.....Batt used......kcal..........kcal........watts
6.6 miles....11.9 mph......33 min.....39 wh..........102..........116...........52

Using the Strava data: 52 watts for 33 minutes = 28.6 Wh. 116 kcal = 134.9 Wh.

Is the watts data just the pedaling energy while the kcal data includes pedaling energy plus resting energy used?

Our bodies use a lot of kcal just keeping us alive. A resting metabolic rate calculator https://www.omnicalculator.com/health/rmr says I use 1625 kcal/day doing nothing. That's 37 kcal in 33 minutes or 43 Wh. Doesn't look like Strava kcal = pedal energy + resting energy. ???

Another puzzling comparison:
Pedaling energy per Strava 28.6 Wh; Battery energy per Mission Control 39 Wh. Battery/me = 136%; Mission Control support level = 195%. ???

strava calorie estimates are active calories, i believe, based on the amount of work done and not your resting metabolic rate.

are you looking at data in strava that the strava app collected (i.e. you were running it in your phone while riding) or did you upload the data from mission control to strava?

in the case of the former, the estimates are totally useless. without a bunch of sensors connected the strava app has no idea how much work you’re doing.

the strava “watts” data is definitely just the pedaling energy. strava has no idea about e-bike battery usage or motor output. however, again, if you didn’t upload the data from mission control (which is connected to the bike’s pedal power sensor) those watt estimates are pretty useless. they don’t take into account wind, drag, bike weight, a million things.

 

[mcdenny]

strava calorie estimates are active calories, i believe, based on the amount of work done and not your resting metabolic rate.

are you looking at data in strava that the strava app collected (i.e. you were running it in your phone while riding) or did you upload the data from mission control to strava?

in the case of the former, the estimates are totally useless. without a bunch of sensors connected the strava app has no idea how much work you’re doing.

the strava “watts” data is definitely just the pedaling energy. strava has no idea about e-bike battery usage or motor output. however, again, if you didn’t upload the data from mission control (which is connected to the bike’s pedal power sensor) those watt estimates are pretty useless. they don’t take into account wind, drag, bike weight, a million things.

The Strava data was uploaded from Mission Control after the ride was complete.

Here's what I don't get. Calories and watt hours are energy units just like kilometers and miles are distance units. In the ride shown above Strava says I exerted 52 watts for 33 minutes. That's 28.6 Wh. It also says I used 116 kcal. That's 134.9 Wh. What am I missing?

 

[mschwett]

The Strava data was uploaded from Mission Control after the ride was complete.

Here's what I don't get. Calories and watt hours are energy units just like kilometers and miles are distance units. In the ride shown above Strava says I exerted 52 watts for 33 minutes. That's 28.6 Wh. It also says I used 116 kcal. That's 134.9 Wh. What am I missing?

that’s about right.

the efficiency of the human body as a motor for cycling is around 25%. if you burn 1000 calories, 250 of them go into motion at the cranks. 28.6 * 4 = 114, pretty close to 134.9. the slight variability of efficiency is why the calorie estimates are just that, some people are a little more efficient than others.

 

[Jeremy McCreary]

that’s about right.

the efficiency of the human body as a motor for cycling is around 25%. if you burn 1000 calories, 250 of them go into motion at the cranks. 28.6 * 4 = 114, pretty close to 134.9. the slight variability of efficiency is why the calorie estimates are just that, some people are a little more efficient than others.

This raises an interesting question I might look into: Does a rider have any control over her own cycling efficiency?

Control from ride to ride seems unlikely, but how about limited long-term control through some kind of training program?

 

[mschwett]

This raises an interesting question I might look into: Does a rider have any control over her own cycling efficiency?

Control from ride to ride seems unlikely, but how about limited long-term control through some kind of training program?

as i understand it, this is a pretty fixed value based on human physiology / biology. 19-24 percent is an often stated range. what i’ve not ever seen studied is whether you can go from being a 19% person to a 24% person

one could assume, perhaps, that pedaling at a super high cadence is really inefficient due to moving the legs up and down so much. riding on a hot day or with a lot of excess clothing would require a lot more sweating. difficult to digest food would require more blood flow to the gut. no idea if all those factors would be 1% or .1% or .01% or …

 

[Jeremy McCreary]

as i understand it, this is a pretty fixed value based on human physiology / biology. 19-24 percent is an often stated range. what i’ve not ever seen studied is whether you can go from being a 19% person to a 24% person

one could assume, perhaps, that pedaling at a super high cadence is really inefficient due to moving the legs up and down so much. riding on a hot day or with a lot of excess clothing would require a lot more sweating. difficult to digest food would require more blood flow to the gut. no idea if all those factors would be 1% or .1% or .01% or …

Had a chance to search on "metabolic efficiency in cycling" and thumb through Wilson and Schmidt, 2020, Bicycling Science, 4th ed. The latter backs up your 25% rule of thumb WRT gross metabolic efficiency, but a range of 18-23% is often cited in the online articles I looked at.

The huge chapter on human power generation in Wilson and Schmidt had surprisingly little to say about human efficiency and nothing about changing it. However, no shortage of schemes to increase metabolic efficiency on the internet. Guessing most are snake oil. The few I looked at involved long-term combos of intense training and special diets.

No thanks. I'll make do with the efficiency I have.

During my time in medicine, I learned to be very wary of people trying to tell other people what to eat. The evidence behind their advice is often shaky at best.

 

[mcdenny]

that’s about right.

the efficiency of the human body as a motor for cycling is around 25%. if you burn 1000 calories, 250 of them go into motion at the cranks. 28.6 * 4 = 114, pretty close to 134.9. the slight variability of efficiency is why the calorie estimates are just that, some people are a little more efficient than others.

Thanks. now I get it.

 

[fooferdoggie]

with me its even worse I cant eat carbs so all my fuel come from protein and it takes even more energy to convert it to fuel.

 

[PSm]

Had a chance to search on "metabolic efficiency in cycling" and thumb through Wilson and Schmidt, 2020, Bicycling Science, 4th ed. The latter backs up your 25% rule of thumb WRT gross metabolic efficiency, but a range of 18-23% is often cited in the online articles I looked at.

The huge chapter on human power generation in Wilson and Schmidt had surprisingly little to say about human efficiency and nothing about changing it. However, no shortage of schemes to increase metabolic efficiency on the internet. Guessing most are snake oil. The few I looked at involved long-term combos of intense training and special diets.

No thanks. I'll make do with the efficiency I have.

During my time in medicine, I learned to be very wary of people trying to tell other people what to eat. The evidence behind their advice is often shaky at best.

This forum all seems to be coming up with interesting things to consider.

I don’t have a power meter, but my Wahoo Bolt with speed, cadence sensor and a heart monitor, uploads to my Strava account. Always assumed the power and calories consumed data was probably way off.

With my particular ebike, no Mission Control and no way to see exactly how much average power the motor is contributing verses me (though my real time LCD display provides motor output), so I’m out of luck.

Now if I’m riding the analog bike, and Strava says: Calories = 3,522 Cal, is Strava really far off from reality, or in the general range?

 

[mschwett]

…

Now if I’m riding the analog bike, and Strava says: Calories = 3,522 Cal, is Strava really far off from reality, or in the general range?

far off, in my experience. it knows your speed and weight and hopefully the elevation changes, and that’s about it pretty much. you could be sitting straight up in a strong headwind with knobby 2.5” tires, requiring 300 watts to go 15mph or you could be in the drops in a lycra skinsuit with a tailwind and skinny tubulars, requiring 100 watts to do the same.

i’m 6’2 and around 185lb, ride in fairly strong winds and around 50-75’ of climbing per mile, on a very light and moderately aero bike and my calories are almost always in a range from 40 to 50 per mile, which is quite high in general.

 

[PSm]

far off, in my experience. it knows your speed and weight and hopefully the elevation changes, and that’s about it pretty much. you could be sitting straight up in a strong headwind with knobby 2.5” tires, requiring 300 watts to go 15mph or you could be in the drops in a lycra skinsuit with a tailwind and skinny tubulars, requiring 100 watts to do the same.

i’m 6’2 and around 185lb, ride in fairly strong winds and around 50-75’ of climbing per mile, on a very light and moderately aero bike and my calories are almost always in a range from 40 to 50 per mile, which is quite high in general.

Good to know. That particular “3522 calorie” ride was 50 miles, 4300 ft elevation gain, 13.6 mph. But yes, assuming Strava is likely way off. But also not willing to spend $$$ on a power meter, or other $$$ ideas.

 

[Jeremy McCreary]

This forum all seems to be coming up with interesting things to consider.

I don’t have a power meter, but my Wahoo Bolt with speed, cadence sensor and a heart monitor, uploads to my Strava account. Always assumed the power and calories consumed data was probably way off.

With my particular ebike, no Mission Control and no way to see exactly how much average power the motor is contributing verses me (though my real time LCD display provides motor output), so I’m out of luck.

Now if I’m riding the analog bike, and Strava says: Calories = 3,522 Cal, is Strava really far off from reality, or in the general range?

I don't know anything about Wahoo, Strava, and Mission Control, but I do know this: Without a power meter recording — or equivalently, recordings from separate cadence and torque sensors at the crank — nothing meaningful can be said about the total energy you put into the crank between points A and B. Hence, nothing meaningful can be said about the calories you burned between A and B — even with an assumed metabolic efficiency.

Why Strava would even report calories in such a case is beyond me.

 

[Stefan Mikes]

I don't know anything about Wahoo, Strava, and Mission Control, but I do know this: Without a power meter recording — or equivalently, recordings from separate cadence and torque sensors at the crank — nothing meaningful can be said about the total energy you put into the crank between points A and B. Hence, nothing meaningful can be said about the calories you burned between A and B — even with an assumed metabolic efficiency.

Why Strava would even report calories in such a case is beyond me.

Specialized Turbo e-bikes share their power meter data. I regret to think your wife would kill you for buying a Vado though

 

[Jeremy McCreary]

Specialized Turbo e-bikes share their power meter data. I regret to think your wife would kill you for buying a Vado though

@PSm says he doesn't have a power meter. Don't recall what bike(s) he has. Are you saying his bike is recording power some other way? If not, any calorie figure reported would be baseless.

 

[JustRiding]

Just to add another angle of thought.... on a very light e-bike, like a racing bike, the faster you ride, the less you need the battery.
This is because on a light racing bike you naturally exceed the 25 km/h the engine supports you (in Europe) most of the times anyway, hence battery only kicks in during acceleration, upward hills and in strong headwinds. Did an 80 km ride this weekend with my Scott Addict eRide (250 wh battery, bike weights bit over 11 kg) and used only 41% of my battery (mainly for a few short but steep hills and a heavy seaside head wind at the end).
But e-racing bikes are of course a niche. With more mainstream e-bikes, you can barely exceed the max engine-supported speed since the weight of the bike and the engine resistance will work against you from that point.

 

[Stefan Mikes]

@PSm says he doesn't have a power meter. Don't recall what bike(s) he has. Are you saying his bike is recording power some other way? If not, any calorie figure reported would be baseless.

It is correct what you are saying. PSm rides (as I can understand) a single speed traditional bike. The calorie figure calculated by Strava for his ride makes some sense even if it is not very accurate.

 

[PSm]

It is correct what you are saying. PSm rides (as I can understand) a single speed traditional bike. The calorie figure calculated by Strava for his ride makes some sense even if it is not very accurate.

Yes, I was referring to my Strava rides with a SS traditional bike w/ cadence, speed, heart rate and gps data. (Also have a SS Ride1UP Roadster v2 E-bike, but ignoring it for the power discussion. And had two geared bikes, but just donated the one with a derailleur since I don’t ride it anymore. Keeping the IGH one)

 

[mcdenny]

This forum all seems to be coming up with interesting things to consider.

I'm learning a lot too. My interest is understanding my range riding my bike in different circumstances. With two separate energy sources it's not nearly as straightforward as X miles in assist level Y.