It was a small, handwritten notice taped to the window of a shop but it spoke volumes. “For 2019 switch off your device, learn to talk to people again. Use your local shops. If its [sic] cheaper online save up and buy local, remember they are familys [sic] not faceless companies. More convenient online? Don’t be lazy go and get it local. Do more to protect our society this year.”

The message from Paul Duncan, owner of Pauls Custom Cycles in Peckham, south London, which closed just before Christmas, was picked up by the presenter James Corden, who posted it on his Twitter feed last week with the comment: “This is a recently closed down shop in London. I think they may have a point... thanks for sharing.”

Corden’s tweet, which went viral, sparking a predictable row about millionaire expats lecturing others on how to spend their money, is another reminder of the continuing plight of Britain’s beleaguered bicycle shops.

Across the country, cycle shops that have been a regular fixture of their local high streets for decades are closing down in their droves. The bikebiz website regularly tracks closures, compiling an increasingly long list of names. In the last couple of years many illustrious shops have disappeared, including the 105-year-old Ben Hayward Cycles in Cambridge and M Steel Cycles on Tyneside, which had been trading since 1894. In November, the oldest bike shop in Bath, Johns Bikes, which had been trading since the Seventies and once had a turnover of £1m a year, closed.

It is not just an independent shop that is being lost when a store closes, according to Sam Jones, senior campaigns officer at the charity Cycling UK: “When you buy a bike from one of these shops they’re making sure you get the right bike for you rather than the bike you want. You get to try the bike before you buy, you get the expertise. They are a vital part of cycling life in the UK.”

But many customers no longer value these qualities, it appears. A Bicycle Association report found that for every 10 bike shops that closed in 2017 only three have taken their place, the “worst refresh rate since the 1960s when bicycle sales collapsed and when hundreds of Britain’s bike shops closed or moved into different sectors”.

James Corden (@JKCorden) This is a recently closed down shop in London. I think they may have a point... thanks for sharing @Tweet_Dec pic.twitter.com/IkJd6Wc7yj

Even the established chains are not immune. In the autumn Sports Direct tycoon Mike Ashley bought Evans Cycles for £8m after it fell into administration and he recently outlined plans to close up to half of its 62 stores.

Those at the other end of the spectrum are also taking a hit. The Brixton Cycles workers’ co-op in south London, which has existed at various locations for 35 years and commands a loyal following on Twitter, is struggling to stay afloat.

“Up to Christmas it was touch and go as to whether we could get the rent together for the shop,” said Jim Sullivan, one of the co-op’s nine members. “We didn’t pay ourselves until the 15th and this sort of thing is becoming a more regular occurrence.”

The internet is largely to blame, according to Sullivan. Bikes, clothing and components can be bought online significantly cheaper than in shops, which have considerably higher overheads than online brands. “The rent has become quite an issue for us,” Sullivan said. “When we moved premises it more than tripled overnight.”

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Cut-throat margins are reflected in plunging revenues across the sector. In 2010, total bike sales in the UK amounted to £1.49bn but these had declined to £1.28bn by 2016, the most recent figures available and the lowest annual total for seven years. The number of people working in the bicycle trade in the UK dropped from 15,000 to a low of just over 12,400 over the same period.

Like many other bike shops, Brixton Cycles is tweaking its business model in a bid to stay alive. Its members are discussing pay cuts and becoming more flexible about when they get paid. Many bike shops are now focusing on servicing bikes and building them from parts bought online – Brixton Cycles charges £130 to construct a full bike – rather than relying on sales. “We’ve just reduced our shopfloor size to increase the workshop – it’s nearly twice the size now,” Sullivan said.

The decline of high street bike shops, at a time when people are being encouraged to be healthier and to reduce their car use, reflects a wider problem: despite millions of pounds being spent in recent years promoting cycling, the number of people using bikes has remained largely static.

In 2017, 14% of respondents to a national survey said they cycled at least once a week. One fifth also said they cycled, but less often than that. Two out of three, though, reported that they cycled less than once a year, or never. Those figures have hardly changed since 2003, according to Cycling UK, largely because the younger generation think cycling “is too scary”.

Jones drew parallels between the decline of the bike shop and another institution that is falling out of favour with millennials: “Bike shops are like pubs when it comes to maintaining community spirit. In many ways they’re that important.”