I'll begin by saying that controls are weird and uncommon for this genre of games. I played plenty of 2d bike games from Free Rider and Happy Wheels to Elastomania and Gravity Defied. And usually right and left keys are used to lean forward/back and to drive forward and brake you use up and down. Alt, Ctrl and Space are also uncomfortable and I'd prefer something like ZXC. Although, since it appears that mobile phones are your primary platform, your controls scheme would be more suitable.
Zooming out when you're going fast would also be nice, cause sometimes you don't know what to expect, especially when you're falling down.
Other than that it's a fine game, don't have much else to say about it.