I have a new Radrunner 2 and I like the e-bike but the rear brake doesn't seem to be working right. The front brakes work well but when I apply the rear brake it doesn't really slow the bike down no matter how hard I pull on the lever. I cleaned the disk with alcohol but that didn't make any difference. Thanks for any help.
try cleaning the rotor, sanding the rotor and brake pads, bedding, and trying it again. this video is great to govern the process of doing this.:
https://youtu.be/qsZPUyFZaxQ
Did what you suggested and also watched the video, still not as good as the front brake but the rear is a lot better. Thank you.
Make sure the caliper is centered to the rotor. If it is slightly off center, you won't get proper/complete contact between the pads and the rotor. Loosen the caliper mounting bolts that hold the caliper to the frame, so that there is a very slight bit of physical movement of the caliper. Then compress and hold the brake lever while re-tightening the caliper support bolts to the proper Newton Meter specs.Your caliper will now be centered to the rotor.
Try replacing the brake cable. It may be defective causing spongy lever feel.