One of the reasons I don't Mt. Bike....

Another reason: they bike uphill for miles on gravel roads.
Reason 3: Then they fly down tiny deer trails over fallen logs, roots, & slippery muddy slopes, (this time of year).

Luckily, they don't look like this usually, since they try to not ride when it's this muddy out. Give me pavement, the occasional small hill (love riding bikes downhill!) & dry weather please!