My greatest fear about commuting to work by bike, curiously, is not that I’ll slip underneath a passing semi and have my head crushed like a grape.Although, now that I dwell on it, that certainly ranks in the top 10 or so.No, my No. 1 fear – rational or not – is that I’ll go to work at night feeling fine, but sometime, as the night wears on, I’ll be blindsided by an insidious stomach bug.You know the kind, the one that sneaks up on you. First your stomach starts growling. Then it gets a little louder. You start to feel a little : off. Before long, your mouth waters. Your senses, cruelly, heighten. Then you’re praying to the porcelain god as you puke up your toes.Gastroenteritis wipes you out. A couple of bouts of hurling, and all you want to do is sleep. I can’t imagine a worse commute than one done in the throes of the stomach flu. Pedal, hurl. Pedal, hurl. No thanks.I thought about this phobia this week, when another kind of illness knocked me out of the saddle.It masqueraded as a simple cold. It started with a nasty sore throat, followed by a runny nose. It then somehow managed to knock me flat on my, er, back for three days. I believe I slept about 16 hours the first day, 12 the next, then another 14 or so for good measure on Day Three. Fortunately, I only was scheduled to work one of those days, and I didn’t even consider riding to work, I was so wiped.I never felt all that badly. My sinuses hurt. My head ached. My nose was sore. But the biggest symptom was the fatigue.Fortunately, I’m on the mend and back on the horse. I rode to racquetball, then rode to and from work on Day Four, and though I still tuckered out more quickly than normal, it felt good to be back.Now if I can just keep that stomach bug at bay, all I’ll have to worry about is that semi making a grape of my noggin.