Chris Pratt Struggles with Son's Bike As Katherine Schwarzenegger Looks On

If Chris Pratt ever took the SAT test, he's lucky there wasn't a question ... How do you fit a bike in a Tesla?

Chris' fiancee, Katherine Schwarzenegger, apparently made his son Jack's day by plunking down cash for a brand new bike. The 6-year-old's superhero dad, however, struggled to secure the bike inside Elon Musk's handiwork -- to no avail.

Star-Lord did not give up ... his Plan B was Katherine's SUV, where the bike fit nicely.

Chris and Katherine shared a kiss, she took off alone and he took off in his Tesla with Jack. Presumably, they rendezvoused back at the house so Jack could ride to his heart's content.