I thought the Treadwell ebike version was only sold as an EQ, Cannondale also sell a non-ebike Treadwell model so check the rear hub to be sure you’re looking at the electric version.
I have the Treadwell non EQ bike called Treadwell Neo- Court's review of the EQ version states you cannot attach a rear rack on it. However you can on the non- equipped version. I was able to install my 25 year old Blackburn mountain rack.
You don't say where you are in the country but you might look at OHM e-bikes out of North Vancouver.
They are high quality and powered by Shimano eSteps. Court has some reviews up in the Review section.
