We rented two bikes for the day to cycle to Villandry and back. The price was fair and included both the helmets and a repair kit (which some other places charge for separately).
The quality of the bikes was really good and the staff were super friendly and helpful. They spoke English too.
Some additional tips: ask for directions and a map instead of relying on Google Maps. They will show you the safer and more scenic route. Also, the opening times on Google might not be accurate - if you need an early start, maybe call them. For us, Google said they opened at 9:30, but when we went there, we saw they had been open since 9am already.
Finally, they require a deposit of EUR400 per bike. This didn't go through when I booked online, but they just charged me on the spot, so no issues at all.