biking

I do not mean to be pedantic, but do you mean you are taking your bike on the airplane and would it be an easier route to start in Pamplona?
To quote cycelfiesta:

"The section between Pamplona and Logrono is undulating without ever really giving you fantastic views of the countryside in front of you. As you get closer to Burgos, however, and from Burgos to Leon the route becomes flatter and the greener scenery gives way to hundreds of kilometres of arable land, with a few villages dotted along the way. While the countryside here is not exactly boring, it certainly does not showcase the best that northern Spain has to offer"
Nice article with alternative route suggestions before rejoining the Frances at Leon

Your best option is to fly to Biarritz (which is far better served by flights than Pamplona), then cycle to Bayonne station (7.5km) and catch one of the four daily trains that take one hour to reach St Jean-Pied-de-Port. This enables you to start at the beginning of the CF. The route from Biarritz airport to Bayonne station is described in my guide to cycling the Camino Francés.

I second flying to Biarritz if you want to go over the Pyrenees, very easy to get from the airport to the train station and then onto SJPDP. If you have a bit more time starting in Bordeaux (an extra 250km or so) will give you a different experience to most and give you time to find your legs before the Pyrenees. I didn't really understand the rules about bikes and trains in Spain but when I went from Leon to Oviedo I couldn't just take my bike on the train, had to book and go the next day.