The participants in Britain's only known Muslim women's cycling club are having their weekly lesson in a small park close to the East London mosque. "Most have never ridden," says Erika Severina, their cycling instructor. "Some make excuses, such as saying their clothes aren't suitable, but we've found bikes to accommodate that. Others don't want to ride outside. But now we've got them in parks and on back roads."

Learning to ride turns out to be one of the lesser hurdles the group faces. Women from other backgrounds and faiths have taken part, but most are religiously observant Muslims and wear full Islamic dress. The group was formed shortly before the July 7 bombings in 2005 - and in the aftermath it was not an easy time to take to the streets of London clad in a veil. 

Even more off-putting is the significant disapproval the women face from their own community. "Women should not be riding bikes. They are stimulating themselves. If they want to stimulate themselves they should get a man," says one Asian market trader on the pavement outside the Jagonari Women's Educational and Resource Centre in Whitechapel, where the cycling group is based. 

Nurjahan Khatun, the director of the Jagonari Centre, and founder of the cycling project, points out that "there's nothing in the Koran to say that women shouldn't ride bikes". Despite this, various postings on Muslim websites debate the point and the cultural barriers are strong. 

The Jagonari Centre is in the heart of Bengali East London. A few miles away, the London 2012 Olympic site is under construction at Stratford, but comparatively few local girls and women from the Bengali community take part in sport. A 2006 report for Sport England found that only 19 per cent of Indian and Bengali women took part in any sport, compared with 31 per cent for women nationwide. 

Alema, 19, is the co-ordinator of the cycling group. "It's always the boys and their bikes," she says. Her father is an Indian chef and the family lives in Woodford, Essex. She has just started a BA in economics and politics at Goldsmiths University of London, in New Cross. "My parents never said 'You can't have a bike'. I never asked them. I once rode my cousin's bike in Sheffield and I loved it. I rode for three hours non-stop, I didn't want to get off." 

Like many of the younger women in the group, Alema has a Westernised lifestyle and goes rock climbing and camping. But she also takes a more active interest in her religion than the older, more socially conservative, women who attend the Jagonari Centre. She wears the hijab scarf and the jilbab, a long black dress, and says that she became interested in Islam after 9/11. "I didn't know anything about Islam, but people started to say negative things about it, so I felt I had to find out the truth." 

She is considering wearing a face veil, and is not put off by her parents' concern that it will attract negative attention. "This life is full of thorns, the next life is Paradise. So if you want to wear a veil, it's going to be a struggle - but this life is supposed to be about struggle." 

Like other women in the group, however, she says that the best thing about riding a bike is "freedom".

"You don't see many women out cycling, especially in the hijab,"" says Rajana, who is in her twenties and likes to ride the biggest, raciest bike in the group. "I'm a bit of a rebel," she says. 

The other women learn on foldaway bikes with low crossbars to accommodate traditional garments. Various pins and clips are used to stop their long loose clothes getting caught in gears and spokes. Underneath many of the women are wearing fashionable shoes, or flipflops and have painted toenails. They look rather immaculate compared with the cycling instructor, who is wearing fingerless gloves, shorts and torn fishnet tights. 

When the group started, the women rode large cumbersome Dutch bikes, turning tight circles in the tiny closed-off courtyard behind the centre. Now their confidence has grown and the women have already taken part in group rides in Hyde Park and past the Houses of Parliament. 

"When I started the project it was because I had really wanted to learn to ride when I went to university at Cambridge, but I didn't have the nerve," Khatun says. "I started the cycling group and expected young girls to come along, yet what's really surprised me was how many older women wanted to take part as well." 

With low levels of English, older Bengali women have traditionally been one of the hardest ethnic groups to reach. But these are the women who attend the Jagonari Centre to talk to their friends and take part in activities. 

Naz is one such lady, whose commitment to cycling has been dedicated, despite slow progress. She struggles with her knees and finds it hard to work the pedals. At her weekly session the cycling instructor is holding her on with one hand while propelling her along a path with the other. Two other members of the group are watching. 

"She is having problems with the circling," says one. "It's the turning," the other agrees. 

"I'm just frightened I will veer off and hit someone," Naz tells the instructor. 

She appears to be making a beeline for an alarmed group of local drinkers, lounging on the grass.

"Do you know how not to hit someone?" the instructor asks the group. 

After some thought one pipes up "Brakes?"

"My son has told me to get some stabilisers,"" Naz says, both relieved and disappointed to have finished her lesson. She came to England from Pakistan as a young woman, but while her husband works in America she lives in East London with her grown-up son, who is an avid cyclist. "He loved riding his bike when he was a little boy. It would not have occurred to me to have a bike. But now he is supporting his old mum." 

Most of the women say that their husbands and sons are more bemused by their new hobby, rather than opposed to it - although the cycling group had one member who cycled in secret because she feared her father's disapproval. 

Since the group began three years ago, it has seen dozens of women progress from wobbly beginnings to more confident riding, with a little independence thrown in. Khatun is proud that her project has borne unexpected fruit and encouraged the kind of "active citizenship" of which the Home Office would no doubt approve.

On a late Saturday morning session, the younger girls of the club meet and cycle along the backroads of East London to Mile End Park. There they fly up and down paths, rashly ignore instructions about braking and signalling - and cheer on impromptu races across the grass.