The frames on these look way overbuilt. I'm wondering to what extent they could be drilled out & still retain structural integrity (i weigh 175). How would you determine size of holes & spacing?

Are you referring to the bike that looks like a moped with an electric motor?
I doubt that a significant change in weight would come from drilling out the frame. Why not switch to lithium cells to save weight? Steve

Hi Steve. This is the recumbent (human-powered) with the simple box beam frame. It's fairly massive. Of course this may be a crazy or silly idea - i certainly wouldn't consider it with a conventional bike frame, but i'm a tinkerer by nature.:->

I think he has misplaced his E.
BikeE (bankrupt recumbent) vs. ebike (Lee Iacocca's 24V & 36V electrics-uprights and folders).

ebike already went to Lithium ion batteries on their folder, but they still use lead acid on their other models. NiMH is lighter.
I believe Ford's Th!nk Bike had lithium batteries as well before they pulled the plug on that program.

You might not save as much weight as you think. Aluminum weighs .11 lbs per cubic inch. Lets say you cut 20 holes, 1.5" dia. in a 1/8" wall square tube. All that work and you only save .48 lbs.

You won't save enough weight to notice it. A better option is to not supersize those fries. ;^)

I think these hilarious pics should remove that notion that the BikeE frame is overbuilt.
Note the frame bent rather than the chain snapping.

https://joesacher.com/cycling/motorbikee.php

However, if you do put the holes in your frame you can brag about how you transformed the bike frame material from aluminium to Drilleium .

Now that's getting sillium!