Both our Radrunner +?s do it and always the front brake. I tried cleaning the brake rotor with rubbing alcohol but didn?t make a difference. Next I?m going to check that brake pads are cantered.

I weigh 180 lbs and had that issue until I really tightened the quick release. Had to tap it closed with a rubber mallet. An option might be to replace the quick release with a bolt, washers and nut. I never had an issue with any of my my previous mountain bike seat posts slipping.

I ordered 2 RadRunner Plus's last Thursday April 7th  and order confirmation said to expect up to a 10 day delay before shipping. Today I received this email from Rad:

Hi Brent,
We want to take the time to say thank you for choosing Rad Power Bikes. We are excited to have you as a member of this community and hope to get you up and riding as soon as possible.
As you may know, over the last two months our fulfillment partner has experienced system issues. This has resulted in shipping delays as they manually process orders. We're pleased to share that their systems are now back up and running. We are all working hard to catch up on a backlog of orders placed during that time and are estimating your order to ship in the next 20 days.
Once your order ships, you will receive the tracking number and ways to manage your delivery via email.
In the meantime, feel free to reach out to our Customer Support team at any time from 7am to 6pm PT at 877-299-9404, ext. 1, or submit your request in our Help Centre and we'll get back to you as soon as we can.
Please know that we are dedicated to delivering your order as soon as possible, and greatly appreciate your patience and understanding.
The Rad Power Bikes Canada Customer Experience Team