Eurovelo Bike Rental
 

I’m looking for info regarding bicycle rental for the French portion of Eurovelo 6, west to east. Is it possible to rent end to end (Nantes- Basel)? One way rental? Are bikes for such available in Nantes? Paris? This my research phase for a June 2023 ride.

I've never heard of one way rentals. The costs would be much too high. If you were to go with an organized tour, I'm sure they offer something similar. The problem is, you cannot pick your own departure or arrival points.
If you cannot find a tour company to suit you, you could buy a mid priced bike in France. From a sports store like Decathlon

I‘m assuming you’re in the USA. Have you looked into taking a bike with you?
British Airways will count your bike as checked baggage if under 23 kg. But do beware of ”code-sharing”

If you have the time, you could fly to London, take the train to Portsmouth, ferry to Le Havre, and ride west to east (tailwinds!) to Strasbourg for example. Just an idea. I did that a number of years ago. Great trip 😊

I believe the limit is now 70lbs with many airlines. This is what I heard about Iceland airways about a month ago

https://cimg4.ibsrv.net/gimg/bikefor...1f09d6b22d.png

There is an outfit in Brittany, www.bretonbikes.com that is located on the canal de Nantes a Brest that is connected to the Eurovelo network. They have bikes they provide for their clients, but I don't know if they will rent bikes to independent tourers. I think it is run by some Brits and caters to British tourists.

Interesting question. The city of Nantes proposes rentals for as little as 20 euros/month. Perhaps email them and see how things develop?