GEARS AND POWER OUTPUT.

[Clavicle]

Hello folks.

Basic question here.

I have an 8 speed Carrera Crossfire. I'm another person cycling due to Covid. Just got the bike a few weeks go.

Does the gear you use affect the power output?

If I am going up hill and choose a "looser" feeling gear (sorry, crap with terminology) to help me pedal, does this in turn affect how much power I am getting?


If I stay on a "tighter" gear that feels harder to pedal, does this then make the motor give me more power?

My thinking is that with a loose easier to pedal gear, the motor might not be sensing the same amount of power output from me, it won't be registering as much torque. Is this silly or am I correct?


I just want to be sure that I am getting as much assistance on hills as possible from the motor.


Thanks folk

 

[vfr400]

The gears have no effect on the motor power. The power is regulated by the setting on the LCD control panel. Basically, the panel sets a different electric current limit for each level. Within each level, the amount of current given to the motor also depends on how hard you press on the pedals. The current effects how much torque the motor makes, which is what you feel as power and how easy it is to pedal up hills.

You have a natural pedalling speed, outside of which it's not easy for you to get good power through the pedals. The gears keep you in your optimum power range so that you can add your most comfortable power level to the motor and be the most efficient.

Finally, to answer your question, if you choose a gear to low so that you can turn the pedals easily, you might not be able to press them hard enough to get the maximum power.

 

[Nealh]

By looser gear you mean lower gear, rear larger sprocket /cog and or smaller front chain ring. A low gear allows you to spin faster /easier and yes you will get more torque then if you stay in a high gear. it doesn't necessarily mean more speed but is easier for the knee joints. Using a higher top gear smaller rear sprocket gives less torque esp on inclines you can bog the motor down stalling it, this is bad for the knees.

 

[Clavicle]

The gears have no effect on the motor power. The power is regulated by the setting on the LCD control panel. Basically, the panel sets a different electric current limit for each level. Within each level, the amount of current given to the motor also depends on how hard you press on the pedals. The current effects how much torque the motor makes, which is what you feel as power and how easy it is to pedal up hills.

You have a natural pedalling speed, outside of which it's not easy for you to get good power through the pedals. The gears keep you in your optimum power range so that you can add your most comfortable power level to the motor and be the most efficient.

Finally, to answer your question, if you choose a gear to low so that you can turn the pedals easily, you might not be able to press them hard enough to get the maximum power.

So in a sense gears DO have an effect out power assistance? Like you say, I i were to choose a gear so low, I might not get maximum power. That's what I was thinking.

 

[mike killay]

So in a sense gears DO have an effect out power assistance? Like you say, I i were to choose a gear so low, I might not get maximum power. That's what I was thinking.

It all depends on exactly what sort of system your bike has to deliver the power.
1 A torque sensored system will deliver power as a ratio of what you put in by pedalling. To my mind a crazy system but much loved by many of the more athletic on this site. For older/less fit enthusiasts it means that as you near home and are feeling tired you are not able to pedal so hard and thus get less assistance.
2 A PAS system, usually a ring of magnets fitted to the pedal axle. All that these do is tell the motor you are pedalling. The motor will supply full power if your handlebar setting is on high, even if you are 'under pedalling (i.e. just turning the cranks slowly without any effort at all)
This is the most sensible system except for number 3 below.
3 A full throttle which delivers as much power as you decide without any pedalling at all.

 

[cyclebuddy]

It all depends on exactly what sort of system your bike has to deliver the power.

The OP's Carrera Crossfire uses the Suntour Torque sensor.

A torque sensored system... it means that as you near home and are feeling tired you are not able to pedal so hard and thus get less assistance.

Not strictly true in practice; You can apply less pressure to the pedals and simply whack-up the power assistance a level.

There is a fourth system; An RPM sensor which measures pedal rotation speed to gauge how much power to apply. In practice, it rides/feels (to me) very much as a cross between Cadence and Torque, giving a nice balance between the two. You can't "ghost pedal" as the speed will drop off, but if you increase pedal rotation (not based on how hard you're pressing) assistance increases.

 

[mike killay]

The OP's Carrera Crossfire uses the Suntour Torque sensor.
Not strictly true in practice; You can apply less pressure to the pedals and simply whack-up the power assistance a level.

If you lived I where do, there are always proper hills to get home and you are already on full assistance when you get worn out.

 

[vfr400]

There is a fourth system; An RPM sensor which measures pedal rotation speed to gauge how much power to apply. In practice, it rides/feels (to me) very much as a cross between Cadence and Torque, giving a nice balance between the two. You can't "ghost pedal" as the speed will drop off, but if you increase pedal rotation (not based on how hard you're pressing) assistance increases.

That idea sounds logical, but if you try it, you'll see that it's absolutely diabolical. I saw some systems like that about 10 years ago, but I've not seen it on any modern bike.

Some systems, like Bosch, use a combination of torque, bike speed and pedal speed sensors to inform their power control algorithms. The pedal speed part is more for safety and reliability than anything else, to stop the motor giving full power when the pedals are stalled or turning too slowly.

 

[Stanebike]

Looking at pictures of your model of ebike online, the display appears to have a motor power indication by the vertical bars on the right hand side. If this is the case you can try different gears at a constant speed (mph) and on a level road, to see what difference they make to your peddling effort and the motor power. You can try this for any of the different power level settings (horizontally along the bottom of the screen), that you choose. Hopefully that will give you a better feel for the effort of your legs verses the power of the motor.