Technically yes, you can bicycle across the bridge, the better question is should you?
Plenty of opinions regarding this question are posted online from experienced and recreational cyclists, including me. I’ll admit it’s possible to cross the bridge by bike, but just because it’s possible, it doesn’t mean you should do it! The bike path is very narrow, 20 inches to be exact.  This is about the width of my bike carrying filled panniers. The bike lane is sandwiched between a lane of fast-moving bridge traffic and a 8-10 inch high curb, not allowing much leeway for challenges like the suction created by large trucks passing at high speeds, crosswinds, panniers and swerving cars.  There’s not much I dislike more than cycling in narrow spaces, curbs, fast moving trucks and cycling uphill and downhill.  This bridge has 5 km of all of these!  Even the official Loire By Bike website recommends not crossing the bridge by bike for safety reasons.  I’m happy to oblige!
This summer, cyclists will have 4 options for crossing the Loire:

- The best option during the summer season is the free shuttle, pictured above. Â Beginning daily from July 11 to August 15 and on weekends in September, cyclists can take a free shuttle bus in either direction. Â Shuttles hold 8 people and bikes. Â No tandems or cargo bikes are accepted. Luggage, baby carriers and trailers are OK. No reservations required, first come first served. In Saint Nazaire, the shuttle departs from Blvd. des Apprentice near Rue de la Loire. In Saint Brevin, the shuttle departs from Place Bougainville. Â For more information: Â +33 (0) 251826262. Â Click here for schedule.

- Bus+Bike service on Aleop bus #317 from Saint Nazaire to Saint Brevin has 8 spaces for bikes. The route departs from Saint Brevin Town Center and Saint Nazaire railway station. There is one bus an hour. Â Reservations must be made at least one day in advance. Â Call +33(0)240215087 from 9-4, 9-12 on Friday to reserve a space. Â For reservations for Saturday, Sunday or Monday, call before noon on the Friday before your travel date. Â I have not used this service so I can’t comment on how easy it is to use. Â If you encounter problems, you can always seek help from a local tourism office along the route!
- If you have no need to travel to the Loire estuary in Saint Nazaire, there’s a free ferry service about 45 km east of Saint Nazaire that runs in both directions from from Le Pellerin to Coueron. The ferry runs from 6:30am in Coueron, and 6:20am in Le Pellerin, then every 20 minutes all day. Â No reservations required.
- Taxi+Bike service, departing from both Saint-Brevin-les-Pins and Saint Nazaire. Â Taxis can transport 4 people and 4 normal bikes. To request a car or for more information contact Taxi St-Brevin at +33(0)240272307 and Taxi Saint Nazaire at +33(0)240660262.
I hope this information helps with your planning and that you have a safe cycling holiday!
I have cycled this bridge several times and never found it a problem. The views are fantastic. It is good, however to hear of alternative routes, including the bac. Cycling guides are often quite unclear on this. A similar state of affairs exists for some UK bridges.