Most if not all hard disk based players employ the practice of spinning up the drive, reading the data to memory and spinning back down. They do this primarily for power consumption but obviously it also serves to lessen the risk to the drive.
I've been bashing and banging around mp3 players since the Rio300. For cycling, really for any sport activity, you want to go with a flash based player. The smaller, the better. The iPod shuffle is a great example, there are plenty of other alternatives. You don't need a display, you don't need a ton of memory.
For cycling (commuting, long rides), I use a shuffle (the older stick of gum sized one). 512 mb, plenty of tunes for a 6-8 hr ride. I have it velcro'd to the side of my helmet, easy, convenient and out of the way.
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.