Trail Cruiser
Well-Known Member
Some may find this to be too technical but there are also few others who want to ponder on the inner workings of the gear reduction mechanism and the gear ratio.
I know the BBSHD has 2 stage gear reduction using pinions and gears and has a gear ratio of 21.9:1.
The Brose uses planetary gear in the first stage of gear reduction and the second stage is a belt drive. And Brose openly discloses the ratio to be 30:1.
The TQ drive uses an exclusive single stage harmonic drive gear reduction and the ratio is openly disclosed at 37:1.
The Shimano e series looks like it has 3 stages of gear reduction for the E8000 but 2 stage for the E6000, and the ratio is not disclosed.
By looking at the Bosch performance line mid drive, it also uses 2 stage pinion-gear reduction, by counting the teeth, it shows a gear reduction of 7.2:1 but since it uses a smaller chain ring, the overall ration is about 18:1 (still, a relatively high speed ratio). There is also a metal gear mechanism for the pedal side at 2.5:1 ratio.
Now lately, I started counting the teeth of the Yamaha. It also uses 2 stage pinion-gear reduction and the final ratio is at 45.77:1. This means, you can use a smaller motor but it has to spin very fast. At higher cadence you may get little support.
As you can see, the higher the final ratio, the higher the torque at the expense of high cadence capability. The lower the ratio, the higher the cadence capability but at expense of low speed torque (assuming the motors are the same, but of course, the motors are not the same and is a separately topic of its own).
I know the BBSHD has 2 stage gear reduction using pinions and gears and has a gear ratio of 21.9:1.
The Brose uses planetary gear in the first stage of gear reduction and the second stage is a belt drive. And Brose openly discloses the ratio to be 30:1.
The TQ drive uses an exclusive single stage harmonic drive gear reduction and the ratio is openly disclosed at 37:1.
The Shimano e series looks like it has 3 stages of gear reduction for the E8000 but 2 stage for the E6000, and the ratio is not disclosed.
By looking at the Bosch performance line mid drive, it also uses 2 stage pinion-gear reduction, by counting the teeth, it shows a gear reduction of 7.2:1 but since it uses a smaller chain ring, the overall ration is about 18:1 (still, a relatively high speed ratio). There is also a metal gear mechanism for the pedal side at 2.5:1 ratio.
Now lately, I started counting the teeth of the Yamaha. It also uses 2 stage pinion-gear reduction and the final ratio is at 45.77:1. This means, you can use a smaller motor but it has to spin very fast. At higher cadence you may get little support.
As you can see, the higher the final ratio, the higher the torque at the expense of high cadence capability. The lower the ratio, the higher the cadence capability but at expense of low speed torque (assuming the motors are the same, but of course, the motors are not the same and is a separately topic of its own).
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