u r right-- the vibration would damage hard drive based player such as ipod.

although, if u want to buy an ipod, then just buy ipod nano- which is flash based and it is suitable for biking and all kinds of acitivity and it is the thinnest and lightest player around so u won't feel its weight while biking.

--there are also other flash based players from IRIVER which are awesome, too in addition to CREATIVE mp3players
but i still prefer u getting ipod nano

hope this helps!!