Bosch drive unit chainring revolution

[jimmy kim]

Hi everyone, I have a question regarding the number of chainring revolutions per crank arm revolution. I have seen a number of videos reviewing ebikes with the Bosch e-bike system and learned that the chainring revolves 2.5 times for every single crank arm revolution. and it raised some questions for me:

1.I'm wondering if this is the case even when the ebike system is completely off?

2.if that's still the case with the ebike system on but with the power assist mode off ?

3. does the number of chainring revolution per crank arm revolution change according to the power assist most with the maximum being 2.5 chainring revolutions per every crank arm revolution?

thank you for your response in advance.

 

[Ballynoes]

Hi,

Not sure what you mean by "chain ring revolutions" but no matter what mode you are in, the physical gears don't change.

Every revolution of the crank will have an effect on the rear wheel depending on the gear you select.

The motor only provides added power making it easier to pedal; it won't change any of the mechanical settings you make.

One revolution of the crank will do xxx revolutions of the cassette, and therefore xxx revolutions of the rear wheel, depending on the gear selected.

So the number of revolutions of the rear wheel, will NOT change with mode selected, simply because it is physically connected by a chain.

However it will be easier to pedal depending on the mode you select.

 

[Trail Cruiser]

Hi everyone, I have a question regarding the number of chainring revolutions per crank arm revolution. I have seen a number of videos reviewing ebikes with the Bosch e-bike system and learned that the chainring revolves 2.5 times for every single crank arm revolution. and it raised some questions for me:

1.I'm wondering if this is the case even when the ebike system is completely off?

2.if that's still the case with the ebike system on but with the power assist mode off ?

3. does the number of chainring revolution per crank arm revolution change according to the power assist most with the maximum being 2.5 chainring revolutions per every crank arm revolution?

thank you for your response in advance.

To answer your questions,
1.I'm wondering if this is the case even when the ebike system is completely off? Yes.
2.if that's still the case with the ebike system on but with the power assist mode off ? Yes.
3. does the number of chainring revolution per crank arm revolution change according to the power assist most with the maximum being 2.5 chainring revolutions per every crank arm revolution? No.

Let's say, for example a 20t Bosch chainring and a 50t non-Bosch standard chainring. One full turn of the standard crank will move the chain to a distance equivalent to 50 links (50 teeth will pull 50 links). For the 20t Bosch, one turn of the crank equals 2.5 turns of the chainring, so 2.5 x 20 = 50 therefore, 1 crank turn is also = 50 links pulled or moved.

 

[jimmy kim]

Thank you Ballynoes and Mark Peralta for your answers. and thank you Mark Peralta for making it clear for me. I appreciate it!