How big?

huh that's nuth'n! some mountain bikes have 29" wheels!

all bikes should have 20" wheels!

Indeed they should, indeed they should. 29" wheels should be reserved for the insanely tall people that are over 7 feet tall and teh rest of us should ride the wheel of champions that is the 20" BMX wheel!! :)

wrong wrong wrong. you haven't listened to anything I've told you have you? 20" wheels usually have way too many spokes, making them a bugger to true, there's just no point bothering with brakes, and growed up people on bmx bikes just makes the younger generations snigger.

hahahahahaha 20" wheels are far more rigid than 26/29" ones, so less likely to need trueing and if you can ride them properly, the young'uns just call you "old school" ;)

first time I've seen fart spelt s-c-h-o-o-l! ;-)

hahahahahahahahahaha thank you soooo much!! :P