The 18th edition of PBP will start on 16th of August, 2015. Many questions about the processes of pre-qualification and registration are already answered in the brochure produced by Audax Club Parisien.
The simple best information we can provide you for the current ride year (the ride year ending 31 Oct 2014) is the longest BRM or LRM (200, 300, 400, 600, 1000 or 1200+) ride will allow you to pre-register for PBP earlier. So this year, get out and ride.
As more information becomes available we will update the PBP webpages (linked from the main menu on the left). Jump to the information now via this link, and definately recommend reading the brochure!