Speed vs battery life

[Tbill]

Has anyone seen any videos or done any tests to see how much speed affects distance?
It would be interesting to see if you can get a few more miles per charge by reducing your speed by 3 or 4 mph.
I assume just wind resistance alone would be greatly reduced.

 

[Roamers]

Bosch has a distance estimator that you can change several variables including velocity.

 

[fooferdoggie]

it can be big. but here is a good one with the default tires on my trek I knew the range and speed. I tended to go 18 to 19mph changing to faster tires I tend to go 20 to 21 but I got 8 more miles range. so lots of factors can make a difference.

 

[keithj69]

Ride ebike at full PAS/throttle, record.
Ride bike at lowest PAS/no throttle, record.

Check out electric bike reports on range tests associated with said ebike, easier to figure your question out.

But yes it matters.

The following test from them made me decide on the Werk. I can say that I run the bike at full PAS, use the throttle in important times and can get a solid 50 miles on the 20ah battery at top PAS. I did upgrade the chainring by 2 teeth.
Court's review of the bike and the company was also a huge decision why i bought the Werk.

 

[rich c]

Battery range goes down exponentially above 20mph. The aerodynamics of the human body are not good.

 

[PSm]

Absolutely makes a difference, and can be huge. Will vary greatly, depending on the individual, bike, power, level of assist, your aero position, and more. No way to know, unless you try yourself.

 

[Mr. Coffee]

Battery range goes down exponentially above 20mph. The aerodynamics of the human body are not good.

I'd actually qualify that and say that optimum efficiency is around 12-14mph. Beyond that you are using your electrons to push air more than you are using them to push you and the bike.

 

[fooferdoggie]

I'd actually qualify that and say that optimum efficiency is around 12-14mph. Beyond that you are using your electrons to push air more than you are using them to push you and the bike.

but depending on the bike I dont even need a motor at that speed. on our tandem on group rides I turn the motor off at that speed.

 

[6zfshdb]

Changes in speed caused by erratic pedaling, throttle use or stopping frequently can create wasteful current spikes that also affect range. I found through experimentation that maintaining a constant speed can improve range by as much as 14%.

I get the best range results by setting the cruise control and pedaling to assist the motor rather than using PAS to have it assist me.

 

[dodgeman]

Wind resistance is roughly based on the square of your speed. This means if you double your speed the wind resistance goes up 4 times. Triple your speed and wind resistance goes up 9 times.

 

[AHicks]

I'd actually qualify that and say that optimum efficiency is around 12-14mph. Beyond that you are using your electrons to push air more than you are using them to push you and the bike.

I'd add that a LOT of rookie riders emphasize how fast they can go when they first get that new bike. It's only later, after riding a few hundred miles, that many realize it's not so much about how fast the bike will go, it's usually more about how FAR it will go! THAT'S when they figure out slowing down can/will dramatically increase the "how far". So agreed, the low teens is a good balance of time vs. distance, with the note that if you aren't in a hurry, a little slower is often even more efficient (like 10-12mph).

 

[mcdenny]

I just did some speed vs range vs PAS setting tests on my Specialized Turbo Como 3.0. Same test loop in all cases.

Bottom line: With moderate pedaling effort (16 calories/mile) in low PAS averaging 10.4 mph the bike consumes 6 Wh/mile giving about 80 miles range. Similar effort (13 cal/mile) but high PAS averaging 16.2 mph uses 13 Wh/mile implying a 37 mile range. So, yeah, speed makes a huge difference in range. So does the pedaling effort you contribute.

Interestingly I did a test loop in high PAS but pedaling with as little effort as possible just to keep going around 10 mph. My bike doesn't have a throttle so I have to pedal a little to get the motor to work at all. 6 cal/mile from me, 10.6 Wh/mile from the battery, 11.8 avg mph. Range with virtually no effort would be 45 miles.

The calories from me are certainly only a very rough estimate as how could the Mission Control software really know? Moderate effort for me (75 y/o, moderately fit) is the rate I can comfortably sustain for maybe 30 minutes.

 

[Stefan Mikes]

With moderate pedaling effort (16 calories/mile)

It is not a moderate effort. 180 W leg power of yours is a significant effort

 

[fooferdoggie]

16 calries per mile is maybe average 120 watts or less on the ride. I just did 140 watts average on my 8.5 mile ride and burned 225 calories thats about 28 calories and a average heart rate of only 107.. but thats on my commute with a lot of stops and starts. my heart rate drops a lot on all those stops.

 

[mcdenny]

1 Wh = 0.86 Kcak (kilo calories and calories are used interchangeably at least here in USA). 16 cal/mile = 18.6 Wh/mile. My 6 mile test loop = 112 watt hours from my effort. Battery supplied 36 Wh. Mission Control says that was 195% support. Don't have any idea how it calculates that. Anyone?

Calories and Wh are energy terms, watts is a measure of power, an instantaneous value as is horsepower. At average 10.5 mph, 6 miles takes 0.57 hours so my average leg output was 196 watts.

https://www.verywellfit.com/walking...887154#toc-calories-at-a-typical-walking-pace says a 180# person walking normally burns 96 cal per hour. My bike exercise noted above would give 168 cal/hour or 175% of normal walking effort. That seems about right. I could walk for 2-3 hours easily but I never could keep up the 16 cal/mile pedaling for nearly that long.

It's raining here today but tomorrow I hope to try a much longer 15-20 mile ride and record the same data. The more I dig into this the more curious I get.

I built a couple of electric boats and now drive a Tesla so I've looked into range vs speed quite a bit. The E bike is an even more complex situation with me and the battery both supplying power. We have been talking about battery range but I want to learn more about my body's range too.

 

[mcdenny]

16 calries per mile is maybe average 120 watts or less on the ride. I just did 140 watts average on my 8.5 mile ride and burned 225 calories thats about 28 calories and a average heart rate of only 107.. but thats on my commute with a lot of stops and starts. my heart rate drops a lot on all those stops.

That's almost double my cal/mile. I don't have a heart monitor but it doesn't seem like it goes up noticeably when I'm riding with this 16 cal/mile effort.

What was your average speed on that ride?

 

[fooferdoggie]

That's almost double my cal/mile. I don't have a heart monitor but it doesn't seem like it goes up noticeably when I'm riding with this 16 cal/mile effort.

What was your average speed on that ride?

I have a HRM and a watt meter so I know how much I am putting out. usually my Nyon display agrees with the garmin on calories burned. without a watt meter its pretty much anything. if I use my apple watch it will give me almost double the calories burned. I dont think anyone really knows how many calories you actually burn. my watt meter and heart rate are the only important factors. I dont get as high of a watt average on my trek as it I do my on my bulls it would be around 150 watts 250 calories and maybe 130hr.

 

[Stefan Mikes]

1 Wh = 0.86 Kcak (kilo calories and calories are used interchangeably at least here in USA). 16 cal/mile = 18.6 Wh/mile. My 6 mile test loop = 112 watt hours from my effort. Battery supplied 36 Wh. Mission Control says that was 195% support. Don't have any idea how it calculates that. Anyone?

Calories and Wh are energy terms, watts is a measure of power, an instantaneous value as is horsepower. At average 10.5 mph, 6 miles takes 0.57 hours so my average leg output was 196 watts.

https://www.verywellfit.com/walking...887154#toc-calories-at-a-typical-walking-pace says a 180# person walking normally burns 96 cal per hour. My bike exercise noted above would give 168 cal/hour or 175% of normal walking effort. That seems about right. I could walk for 2-3 hours easily but I never could keep up the 16 cal/mile pedaling for nearly that long.

It's raining here today but tomorrow I hope to try a much longer 15-20 mile ride and record the same data. The more I dig into this the more curious I get.

I built a couple of electric boats and now drive a Tesla so I've looked into range vs speed quite a bit. The E bike is an even more complex situation with me and the battery both supplying power. We have been talking about battery range but I want to learn more about my body's range too.

I really do not want to analyse it. It does not help anyone just to convert the kcal to Wh because there also is the efficiency of the human body which is 20-25% depending on the assumption. Also, the Mission Control figures are not comprehensive.

If you could upload some of your rides to Strava @mcdenny then Strava converts the data from Mission Control (or Wahoo or Garmin as connected to a Specialized e-bike) and it comes with own kcal values, which is something we could compare (I use Wahoo/Strava for my rides not Mission Control).

 

[Jeremy McCreary]

Wind resistance is roughly based on the square of your speed. This means if you double your speed the wind resistance goes up 4 times. Triple your speed and wind resistance goes up 9 times.

NERD ALERT: A while back, I posted graphs of the 3 main resistances in cycling as fractions of the total resistance encountered at a given ground speed Vg. These 3 main relative resistances are

Qa = (air resistance) / (total resistance)
Qs = (slope resistance) / (total resistance)
Qr = (rolling resistance) / (total resistance)

The input parameters (from Wilson & Schmidt, Bicycling Science, 2020) were those for a 65 lb commuter-ish ebike in 4 different smooth-pavement scenarios:
A. No grade, no wind
B. No grade, 10 mph headwind
C. 5% grade, no wind
D. 5% grade, 10 mph headwind

For a given ground speed and total weight (bike + rider), the calculated resistances are the same with or without a motor. A motor and its added structural requirements add both weight and power. Higher ground speed always results in higher Qa for the simple reason that slope and rolling resistances depend on total weight, not on speed.

By following the relative resistances through Scenarios A-D, you can get a feel for what you're fighting under some common riding conditions. One useful way to do this is to focus on the crossover speed at which air resistance reaches 50% of total resistance — i.e., where Qa = 50%.

At any given moment, the most effective way to conserve battery or muscles or both will depend in part on whether you’re above or below crossover speed.

 

[Stefan Mikes]

NERD ALERT: A while back, I posted graphs of the 3 main resistances in cycling as fractions of the total resistance encountered at a given ground speed Vg. These 3 main relative resistances are

Qa = (air resistance) / (total resistance)
Qs = (slope resistance) / (total resistance)
Qr = (rolling resistance) / (total resistance)

The input parameters (from Wilson & Schmidt, Bicycling Science, 2020) were those for a 65 lb commuter-ish ebike in 4 different smooth-pavement scenarios:
A. No grade, no wind
B. No grade, 10 mph headwind
C. 5% grade, no wind
D. 5% grade, 10 mph headwind

For a given ground speed and total weight (bike + rider), the calculated resistances are the same with or without a motor. A motor and its added structural requirements add both weight and power. Higher ground speed always results in higher Qa for the simple reason that slope and rolling resistances depend on total weight, not on speed.

By following the relative resistances through Scenarios A-D, you can get a feel for what you're fighting under some common riding conditions. One useful way to do this is to focus on the crossover speed at which air resistance reaches 50% of total resistance — i.e., where Qa = 50%.

At any given moment, the most effective way to conserve battery or muscles or both will depend in part on whether you’re above or below crossover speed.

You seem to have forgotten the fourth resistance Jeremy, which is the kinetic energy loss on stopping/restarting the ride.