How do I lock the radio station on my ipod nano?

I cycle a lot and mostly use the radio when riding. Most every time, something rubs agains the surface and changes the station. With my XM radio there is a physical button that will lock all settings.

I would like to know if there is something similar with the ipod nano to lock the current settings (station & volume).

If this is not possible is there a hack where I can make this happen? I have a shoulder strap but sometimes just put the device in my pocket or shirt pocket and have the same problem so I am looking for a solution to lock the current settings.

If this is not possible can this be made as a feature to the next generation device?