Convicts in Hermanice prison in the eastern Czech city of Ostrava are trying to do a good turn by volunteering to fix old bicycles for charity organizations so that they can be used by kids in rural Gambia to reach distant schools.
Surrounded by tools and air pumps, the inmates spin wheels, bicycle chains and gears in two prison workshops under the watchful eye of armed guards.
Vaclav, a bearded 35-year-old serving 20 months for theft, expertly fastens brake pads on a blue BMX-type bike with thick, black tyres.
"It's good to know someone will use these bikes -- they're not the newest," he told AFP.
Karel, a tall, tattooed construction worker who looks much older than his 46 years, is also serving time for theft.
"If it helps people, it's a good thing," he says bashfully.
Unlike other inmates who sort scrap metal or dismantle old cars for cash, the bike crew work for free.
Aside from a sense of satisfaction, they receive small perks including coffee, tea or cigarettes and a good word to courts ordering their probation, says deputy prison chief Petr Cejka.
Since September 2013, prisoners have repaired more than 1,600 bikes -- four container loads that were then shipped to Gambia.
"It costs about 100,000 koruna (3,650 euros; $5,000) to ship one container," says Roman Posolda, head of the Bikes for Africa charity, now starting its third year in the Czech Republic.
Tall, thin and sporting a pony tail, the 42-year-old once cycled around the globe.
He drew inspiration for the charity from a similar project in Britain, where he spent six years working with at-risk youths.
- Free-wheeling charity -
Speaking from the Gambian capital Banjul, coordinator Babucarr Touray told AFP the bikes are a treasure for local children who must travel up to nine kilometres (5.5 miles) to school every day.
"Transport in some parts of the Gambia is impossible," he said, calling the programme "really helpful".
The kids use the bikes "purely to acquire education. We have holidays now and all the bicycles had to come back to school."
Participating schools have a teacher and student trained to do repairs using tools also supplied by the charity and spare parts from bikes broken down beyond repair.
So far, Czechs have handed over some 15,000 bikes to the charity, which operates 120 collection points nationwide.
"We get bikes ranging from very good and new to very old. Only half are suitable for the African terrain," Posolda told AFP.
Mountain bikes prevail, but he says that simple single-speed Czech-made bicycles with coaster brakes able to stand up well to sand and dust are ideal.
The last shipment in May delivered more than 800 bikes to nine schools in Gambia, a west African country that was a British colony until 1965.
A charity shop in Ostrava, charity runs and sales of collector bicycles as well as private donors cover shipment costs.
Bikes for Africa is also renting out bicycles at a mid-July rock festival in Ostrava, which this year features Led Zeppelin legend Robert Plant and French songstress Zaz.
Despite having cycled the globe, Posolda has given up long-distance bike trips for the moment as he waits for his "small kids to grow up".
"I rather help others ride. And that makes me as happy as if I would be cycling myself."