I'll start with a little story.
I have a brilliant Cannondale Caadx Cyclocross bike. Brilliant. It's my commuter. The other day, without very much warning, it went EEEKK< GGGRRRHHKKK< SNNUUURKKK CRACK!...and the cranks went all wobbly. I limped home to find one of the races had exploded.
No problem, purchase some new bearings, fit 'em, back on we go. Except now the non-drive side crank wouldn't stay tight.
I tighten it up a few times and then on the way home the crank falls off. Thread stripped. I'm assuming this was related to the bearing failure. Or not.
Anyway, I've now got 7 miles to ride one legged. As I lurch along, some joker on a mountain bike passes me. He's going quite quickly and I'm sorry, but no-one passes me.
So if you were passed by a guy cycling a silver CX bike with only one leg then
a)Sorry, it's a failing in my psyche.
b)A guy cycling with one leg is faster than you.
So then, after a few beers it has to be said, I purchase a new set BB30 cranks from ebay which upon arrival turned out to be MTB so they're much wider and stronger looking.
I don't care what they look like but will they fit my CX bike?