I'm so slow...that when there's a turtle on the road, it runs me over.
I'm so slow...that I can watch people mow their entire lawn while I ride past it.
I'm so slow...I can't mountain-bike, because the roots keep growing through the spokes as I ride.
I'm so slow...that a century is how long it took, not how far I rode.
I'm so slow...my daily ride takes me two days.
I'm so slow...that if I rode a tandem, the stoker would pass me up.