The walk-in (no motor vehicles allowed) hiker-biker sites at the Whistlers campground near the town of Jasper survived the recent Whistlers campground renovation. Those sites are available to cyclists without reservations. The walk-in sites at Whistlers are not advertised. I have never had a problem getting a site there without a reservation. The number of cycletourists on the Icefields Parkway has been falling rapidly over the last few years due to the horrendous increase in motorists on the Icefields Parkway, especially at the Lake Louise end of the Parkway.

The rest of the Parkway is a camping issue for cycletourists due to filthy motorists reserving all the camping spots. I never wild camp along the Parkway. It's not allowed and there is a very real bear issue along the Parkway which you can make more dangerous for everyone by wild camping. There's the hostels and also the hotels, which can come in handy if you are lazy (like me) and can't be bothered to set up a tent, especially at the Icefields Center, where the hotel is attached to the restaurant (I am also too lazy to cook). I always seem to get good rates at the hotels as a walk-in without a reservation. Room availability may be an issue mid-summer.

You can also ride the whole Parkway in one day and avoid camping between Jasper and Lake Louise or Banff. There is much less motorized traffic late at night.