I second what Bikeless said. I can eat pretty much whatever if the crohn's is quiet, but if it's cranky I tend to bring foods I know to be pretty safe. There are rides where I am just not hungry, so for those I always make sure I have multiple packets of chocolate gu. I usually can eat a power bar also on those days. But anything other than that, it's tough. I do try to take any symptoms in stride that may happen on the bike. Cramps will pass if I just slow down or stop for a minute usually. There's usually a bathroom or at least a field within sprinting distance if need be