River Adagio exterior in port

(4:10 p.m. EDT) -- The latest river cruise company to embrace the active touring trend, Grand Circle has added bikes to some of its river and small ships.

The test involves river ships River Adagio and Provence, as well as Arethusa and Clio, which are part of the line's growing small ship fleet. In a blog post on their website, the line said that the bikes have been in use since this summer, with passengers checking them out at reception.

In the post, the line noted that adding bikes had been a challenge, due to space constraints for storage. The solution? Foldable Brompton bicycles.

"The Brompton was conceived as 'a product that increases people's sense of independence and increases people's sense of freedom,' and we feel this perfectly matches our own goals," Alastair Newton, Director of Nautical and Land Planning, said in the post. "They are handmade in London and considered to be the number one folding bike, which we chose due to the challenge of storing them onboard. This means they can be made available at every stop, not just the big towns where bikes can be rented."

The bike excursions are independent. Passengers reserve the bikes at reception, where they also receive route suggestions and a leaflet with safety tips and cycling rules for the country. Crew members teach the riders how to unfold and fold the bikes. Riders are also given helmets, safety vests and a GPS trackers with SOS buttons that alert the ship in case of emergency.

The line said it's too early to tell if bikes will be put onboard all of Grand Circle's ships. Feedback from this summer's test will be gathered and evaluated.

Biking and other active excursions, such as hiking and kayaking, have become a real trend for European river cruises, with most lines adding bikes and options for people who want more than a walking or coach tour. For more info, check out Best Active River Cruises and Best River Cruises for Bicyclists.

--By Chris Gray Faust, Senior Editor