What--4,000 isn't enough?
Try the 12,000-15,000 that start the L.A. Marathon Bike Tour, about half of whom don't seem to have been on a bike in 5 or 10 years and are correspondingly dangerous. You obviously won't do anywhere near the same mileage, but the crashes (see "dangerous riders" above) and the screwball bikes (waaaa-a-a-a-ay beyond Frankenbiking) are great compensation. Besides, you can do the whole flippin' ride in a bit over an hour, and then have plenty of time to pick out a good spot to heckle the runners when they come by, then get breakfast and follow that with a real ride.