You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
I think they were by diamond back or someone similar.
Looked like box with a longer seat tube
So the top tube ran down sloped.down to the head tube
Only downward sloping top tube that springs to mind is the Haro Extreme.
[img] 
[/img]
Box like could have been S Bike, but lack the downward tube element.
Box-like you say?....
[img] 
[/img]
🙂 meant looked like bmx
Somebody did a klunker type bike with a coaster brake not long ago that had bmx bars
Cannondale Hooligan
Oh, yes, it looks like it might be those GPVs.
20 inch wheels?
Yup.
An attempt to level out sales during the late eighties BMX slump.
I remember borrowing one of these from a friend. It weighed more than my pink Raleigh mustang at the time.
SE Quadangle?
Not a patch on the Raleigh Vektar.
I remember a brand or model named ‘Ninja’ back in ‘89 or ‘90. Their bikes were like this too.
Were they just for going dowhill, fast?
Brooklyn Machine Works?
Charlie - yes. GPV = Gravity Powered Vehicle. Like early X-Games Street Luge, but on “bikes”.
Not a high point for bicycle innovation!