I found that the absolute braking power with properly set up rim brakes and disk brakes is about the same, but nothing can match the precision, sensitivity and repeatability of hydraulic disk brakes.
I've been using hydraulic disk brakes on a couple of my bikes for nearly two years, and I've never adjusted anything on them. That compares with my bike with rim brakes that's gone through three pairs of pads in the same distance, and loads of adjustments along the way. The effectiveness of the the rim brakes varies a lot depending on the adjustment and state of the pads.
With all brakes, whether rim or disk, you can improve the performance a lot by using decent pads. Most cheap brakes have cheap pads, which is why expensive cable disk brakes perform better than cheap hydraulic ones. If you put the same pads in each, you'll find that the hydraulic ones are better.
An important point for ebikes is the cut-off switches. It's very easy to install brake switches in cable systems. You don't have to use those crappy levers with switches. The "hidden wire" type fit in the cable just like a ferrule, and don't cost much. You can fit them at any position in the cable : either end, or anywhere along the length if you cut the cable outer.
http://www.bmsbattery.com/accessory/459-hwbs-hidden-wire-brake-sensor.html
The only hydraulic brakes that I've seen with switches are Tektro E-comp, or you can get an inline hydraulic switch from Magura, which is a bit messy to fit and requires that the system is bled afterwards. There's probably others now as ebikes become more popular.
http://www.ebike-easy.com/products/Bicycle-Parts/BionX-Press-Switch-for-Magura-brakes.html
I've been using hydraulic disk brakes on a couple of my bikes for nearly two years, and I've never adjusted anything on them. That compares with my bike with rim brakes that's gone through three pairs of pads in the same distance, and loads of adjustments along the way. The effectiveness of the the rim brakes varies a lot depending on the adjustment and state of the pads.
With all brakes, whether rim or disk, you can improve the performance a lot by using decent pads. Most cheap brakes have cheap pads, which is why expensive cable disk brakes perform better than cheap hydraulic ones. If you put the same pads in each, you'll find that the hydraulic ones are better.
An important point for ebikes is the cut-off switches. It's very easy to install brake switches in cable systems. You don't have to use those crappy levers with switches. The "hidden wire" type fit in the cable just like a ferrule, and don't cost much. You can fit them at any position in the cable : either end, or anywhere along the length if you cut the cable outer.
http://www.bmsbattery.com/accessory/459-hwbs-hidden-wire-brake-sensor.html
The only hydraulic brakes that I've seen with switches are Tektro E-comp, or you can get an inline hydraulic switch from Magura, which is a bit messy to fit and requires that the system is bled afterwards. There's probably others now as ebikes become more popular.
http://www.ebike-easy.com/products/Bicycle-Parts/BionX-Press-Switch-for-Magura-brakes.html