'American Choppers' Stars -- They Stole My Wheelchair Bike ... Claims Disabled Man

The guys from "American Choppers" got major props for creating a wheelchair-accessible motorcycle -- only problem is they allegedly stole the concept from a disabled biker, and cut the poor guy out of the deal.

Christ Tavantzis -- who suffers from polio -- claims he patented the modified 3-wheeler and pitched it to 'AC' stars Mike and Paul Teutul Jr. at a bike show in 2008.

Now Tavantzis is suing the Tuetul bros because he says they went ahead and built their own version of his trike -- without him -- and then unveiled it at a charity event for the Chris and Dana Reeves Foundation ... where they were lauded for the creation.

In his suit, Tavantzis says it's bad enough polio has taken away his physical abilities -- but now he has to fight to protect his thoughts and ideas too. He's suing for fraud, conspiracy, and discrimination against people with disabilities.