Even if they're quite good at staying on their bicycles, small children are very vulnerable to being knocked off them. It only takes one wobble and they're swerving close to the multiple wheels of an articulated lorry, which is very unrelaxing for their parents to watch.

To avoid this exhausting anxiety we went bicycling along towpaths and a network of disused railway tracks in France's Pays de la Loire region, just this side of Brittany. And because rivers and railway lines are flat, we also avoided a tremendous amount of complaining, as there was no need for exhausting uphill cycling at any point.

France's voies vertes, or green ways, are an amazing state creation. Instead of vaguely lamenting the decline of the railways, the government has converted abandoned tracks into cycle paths. In the past five years, hundreds of kilometres of former rural railway tracks have been covered with asphalt to create miniature motorways through woodland and countryside. They are so beautifully smooth and flat that around the town of La Flèche, I saw people embarking on a 60km route on roller skates, and some of the routes are also wheelchair-friendly.

The smoothness of the tracks allowed our children, aged seven and eight, to ride ahead at speed, stopping only at the occasional road or because they had spotted an interestingly hairy caterpillar or unusually large slug.

William races ahead on the voie verte

We hired bikes for us adults, but were advised to bring the children's own bikes from England, which required buying a sophisticated roof rack, of the kind I've idly observed on the cars of families more energetic and organised than mine, the kind where the bicycles stand vertically on the top.

With careful planning it would be possible to organise a week's cycling, from one overnight stop to the next, with belongings in panniers. But that requires you to have some idea of your children's enthusiasm and stamina, about which we had our doubts.

But I shouldn't have doubted: one day we cycled around 40km without any real difficulty, leaving La Flèche in the morning and arriving at the beautiful Chateau La Lude for lunch. There was only one real incident of noncooperation (a sit-down strike and refusal to continue), soon resolved with the purchase of a can of Coke.

The railway tracks don't run through dramatic scenery, but the landscape of cornfields and forests is lovely, and the route is punctuated by former level-crossing houses and railway stations that have been converted into pretty holiday homes.

We stayed in two places: first at Echologia, a former chalk quarry transformed into a new luxury campsite near Laval in the Mayenne region, and at La Flèche in neighbouring Sarthe.

The Echologia site is another unusual industrial regeneration project. An old quarry has been transformed into an ecological glampsite, with yurts and tipis and goats. The pits have been filled with water, for fishing, and topped with floating cabins where families with children over 10 can stay.

We stayed in a whitewashed wooden cabin on a rocky ridge between two lakes. There is no electricity, but all guests are issued with a head torch to wear as they make their way back to their digs. We felt no overwhelming enthusiasm for the very ecological dry toilets system, but liked having breakfast delivered in a basket to our cabin, with coffee and hot chocolate in thermos flasks.

The very brief time we spent riding on roads at the beginning of the trip reminded me how stressful it is cycling with children in busy traffic. The dedicated cycle routes, when we got there, were a huge relief. The risk of falling into the Mayenne river from the towpaths was very slim, because there was a deep bank of wild flowers and mint between the track and the river. Rose, eight, picked the mint and held crushed bunches beneath her hot palms on the handlebars, trying to create scented minty trails for the rest of us to inhale.

We spent a day riding through the forest of Bercé, which was beautiful but bumpy and much less flat. This was much harder work for the children.

The tourist office guide to the voies vertes advises: "Remember that it's always nice to say bonjour." This advice our daughter adopted with delight, greeting everyone she passed with a bellowed "bonjour" in her as-yet-unrefined French accent.

The peaceful Mayenne river. Photograph: Alamy

There was the occasional moment of protest – when tears popped into their eyes at the idea of getting on the bikes, and they proposed staying in the hotel room and watching cartoons in French. But most of the time I know they loved it, not because they said so but because of the rare absence of complaining.

Naturally the things they found most interesting were not the things we required them to find interesting. On the way from the ferry we took in the D-Day landings museum in Arromanches, the Bayeaux tapestry and the beautiful chateau at Sainte-Suzanne, all of which they observed politelywith mild curiosity. The things they found truly fascinating were the plastic Nutella sachets, a silver, egg-shaped egg boiling machine at the breakfast buffet in Le Verte Galant hotel in La Flèche, and the monstrously noisy red fire-crackers we bought for a euro in a bar in Le Lude.

Sleeping in a cabin on the ferry from Portsmouth was also a massive, unexpected highlight, recorded with such intense detail by seven-year-old William that he exhausted the battery on his new camera – taking around 400 photographs of the bunks and shower unit – and was unable to take any pictures in France.

As we dismounted on the last day, there was a note of regret from the children. "I was actually quite enjoying it," William conceded.

But even if we had wanted to continue bicycling we couldn't have, because of what happened as we drove through a low arch into a car park on the outskirts of La Flèche on our last evening. We registered looks of horror on the faces of several families returning to their cars seconds before we understood what was causing their alarm. There was a nasty metallic crunch as bicycles and roof rack were ripped to the ground.

• The trip was provided by the tourist offices of Mayenne (tourisme-mayenne.com) and Sarthe (tourisme-en-sarthe.com). Ferry travel was provided by Brittany Ferries , which has return channel crossings Portsmouth-Caen from £298 for a car and four passengers. Echologia has yurts, tipis and floating cabins from £65 a night for two, including organic breakfast. Doubles at Le Verte Galant in La Flèche from €73, room only. Information on voies vertes: voiesvertes.com