I use the 20oz Rtic cup with the insert removed on the Kruzer kaddie. The cup will stick in the holder but a little wiggling will free it up to use while riding. As other have said make sure you mount it so it doesn't move.

 

I have the one from Barefoot ******* on mine . I mounted on handle bars.It is also made in the US

 

I like the Leader cup holder. I replaced their cup that comes with mount with a Contigo mug.

It will fit either let or right side of the handlebars., mines is mounted to to the right side.

 

Both ours mounted on the throttle side and speed can be easily control with the left thumb while using cruise control.