Originally Posted by VegasTriker

There are lots of people who have added e-assist to Catrikes. BTW, the "metal bar" is called an axle. Places you could ask are the Catrike forum https://www.tapatalk.com/groups/catrike/, at Bentrideronline, or post a question at the Catrike company site using the contact page. It wouldn't make much difference on the right side because you are enlarging the hole in the derailleur hangar and that can always be replaced. The other side would be a permanent alteration to the frame and irreversible. How much difference is there between the diameter of the existing axle and the new one? I would drill out the extra space rather than file down the rear dropout.