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- Thread starter rjathon
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- Region
- Europe

When you get above just approx. 20 km/h wind resistance becomes the dominant factor. The wind resistance increases with the square of the speed increase, so the wind resistance at 40 km/h will be 4 times as great as at 20 km/h and it costs energy = range.

Have you played with this distance calculator from Bosch? It is surprisingly accurate.

How many kilometres do the different Bosch eBike batteries last? The Bosch Range Assistant displays how many kilometres your pedelec can travel on a single battery charge.

www.bosch-ebike.com

The situation for battery life is worse than this , because the wind resistance power required to double the speed goes u with the cube of the speed, so battery life is affected by a factor of not 4, but 8 for a doubling of the speed.

Also the performance motor in the 380+ appears to be tuned for greatest efficiency at a higher pedal cadence than the lesser motor. This means that even at lower speeds, staying at a low cadence up hills, like 45 rpm say, the 380+ will get you up the hill, but it will consume more battery than the lesser motor will.

yep got to keep them rpms above 70 to get the max out of the motor.

The situation for battery life is worse than this , because the wind resistance power required to double the speed goes u with the cube of the speed, so battery life is affected by a factor of not 4, but 8 for a doubling of the speed.

Also the performance motor in the 380+ appears to be tuned for greatest efficiency at a higher pedal cadence than the lesser motor. This means that even at lower speeds, staying at a low cadence up hills, like 45 rpm say, the 380+ will get you up the hill, but it will consume more battery than the lesser motor will.

- Region
- Europe

It is correct that the power used to overcome wind drag is cubed when the speed is doubled, but the distance travelled at double the speed is also double, so the consumption per km/mi is still 'only' squared.The situation for battery life is worse than this , because the wind resistance power required to double the speed goes u with the cube of the speed, so battery life is affected by a factor of not 4, but 8 for a doubling of the speed.

I’m no expert, so let’s start with that. But I do have a question about your comment - are you recommending keeping rpms above 70 to add more “human power” to the equation to increase range, or are you suggesting the motor is tuned to respond differently/more efficiently at >70 rpm? I ask because I have been under the impression that the motor response is dependent on the torque applied to the pedal. (New to ebikes, so just trying to educate myself.)yep got to keep them rpms above 70 to get the max out of the motor.

Thanks.

Play with the Bosch range estimater. Higher cadence with same velocity = more range.I’m no expert, so let’s start with that. But I do have a question about your comment - are you recommending keeping rpms above 70 to add more “human power” to the equation to increase range, or are you suggesting the motor is tuned to respond differently/more efficiently at >70 rpm? I ask because I have been under the impression that the motor response is dependent on the torque applied to the pedal. (New to ebikes, so just trying to educate myself.)

Thanks.

- Region
- Europe

Low cadence puts more strain on the knees than higher cadence, as at low cadence you have to exert more torque for the same power output. The motor is probably also better at spinning quickly than slowly with greater torque. You can compare it to a car engine which also does not pull well in too high a gear with low revs.I’m no expert, so let’s start with that. But I do have a question about your comment - are you recommending keeping rpms above 70 to add more “human power” to the equation to increase range, or are you suggesting the motor is tuned to respond differently/more efficiently at >70 rpm?

As far as I understand, professional cyclists try to maintain a cadence of around 90 rpm. I find that unpleasantly fast. I have gotten used to 70 - 75 rpm which I find comfortable. Many who ride an electric bike use too low a cadence, perhaps only 50 rpm or so. You have to practice increasing the cadence. At first it feels wrong, but all of a sudden you get used to a higher cadence.

I will check that out. Thanks.Play with the Bosch range estimater. Higher cadence with same velocity = more range.

Ya, got that. My background is with tour/road bikes, so I understand about keeping the cadence up. Makes hill climbing a lot easier too. I just didn’t understand the relationship between cadence and ebike range. I will check out the Bosch range estimator as suggested to see how that works. Thanks.Low cadence puts more strain on the knees than higher cadence, as at low cadence you have to exert more torque for the same power output. The motor is probably also better at spinning quickly than slowly with greater torque. You can compare it to a car engine which also does not pull well in too high a gear with low revs.

As far as I understand, professional cyclists try to maintain a cadence of around 90 rpm. I find that unpleasantly fast. I have gotten used to 70 - 75 rpm which I find comfortable. Many who ride an electric bike use too low a cadence, perhaps only 50 rpm or so. You have to practice increasing the cadence. At first it feels wrong, but all of a sudden you get used to a higher cadence.

because a motor is the most efficient at higher rpms. so the faster your cadence the closer to the optimal the motor runs so you get more out of a battery. Plus you get the most torque out of it. I found on a bosch perfomance speed I have to put out 500 or so watts to max the motor out. before my motor was updated it was only around 450 watts to max it out. but that was only above 70 rpms.Ya, got that. My background is with tour/road bikes, so I understand about keeping the cadence up. Makes hill climbing a lot easier too. I just didn’t understand the relationship between cadence and ebike range. I will check out the Bosch range estimator as suggested to see how that works. Thanks.

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- Europe

Exactly, but the difference in range is not very large, cf. Bosch Range Calculator. Just tested with its default values and with a cadence of 50 (very low!) it showed a range of 81 km (50.3 mi) and cadence 80 gave 85 km (52.8 mi).because a motor is the most efficient at higher rpms. so the faster your cadence the closer to the optimal the motor runs so you get more out of a battery. Plus you get the most torque out of it. I found on a bosch perfomance speed I have to put out 500 or so watts to max the motor out. before my motor was updated it was only around 450 watts to max it out. but that was only above 70 rpms.

It is much more important that with a high cadence, you do not strain either the engine/driveline or your knees so much.

- Region
- Europe

- City
- Mazovia, Poland

Cadence of 77 is my ideal but I force myself to pedal closer to 85, and my mid-drive e-bikes love me for doing that!

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