which caliper

[madcat2020]

What is the replacement caliper for a radrunner plus?
specifically the rear.  They are not available at rad, and I can't see the model number on the caliper.
All I know is it is a tektro aries.

[JimInPT]

Sorry I can't give you the model number, but I can recommend a replacement front/rear caliper set, which happens to be on a very good 1/3rd-off sale until Nov 30th (noticed that when I went to get this link for you):

https://area13ebikes.com/products/juintechm1

I installed these on my 2021 MiniST2 but I think they're used on most/all Rads except the newest models with hydraulic brakes, so your Runner should be no problem.  Very easy to install, a video is on the link above to illustrate, just remove original caliper and drop right in (spacers are included but I don't think I needed any) - they improved brake performance noticeably on the steep downhill grades.  It's double-acting as well, unlike the factory singles, which only move on one side of the rotor.  These are mechanically-actuated hydraulic calipers, so you keep your existing brake cables.

Definitely recommended and I wish I'd been able to get this price a year ago.

Good luck!