What is Top Tube?
1.
The section of a bike frame that connects the head tube (where the forks go) with the seat tube (where the seat post goes). Usually 20-21 inches on a BMX bike. A shorter top tube generally means a shorter wheelbase, therefore making the front end easier to lift. Flatland frames commonly have shorter top tubes (~18.5") for ease of maneuvering. A tall rider may find bruised knees as a result of a top tube being too short.
Jack: Yo, my top tube is 22 inches!
Jill: Compensating for something?
Jack: Blow me.
<James winces as the cross brace collides with his
junk >
Jeremy: HAHAHA! That's what you get for trying a flatland trick!
<James moans>
James: Yeah, I was looking into a flatland frame with a shorter top tube...
Jeremy: Panzy.
See