A Dublin cyclist has been fined for causing a breach of the peace at a branch of Halfords after he threatened to stab a sales assistant during an argument the cost of replacing an inner tube.

Laurence Maguire, aged 62, had gone to the store at Malahide Road Business Park in Coolock in the Irish capital's Northside after the tyre on his bike’s rear wheel punctured, reports Independent.ie.

The Halfords employee told Dublin District Court that Maguire became angry when he was told it would cost €9.99 (£8.26) to replace the inner tube.

It is unclear whether that reflected just the price of the inner tube or the cost of fitting it, or both.

The sales assistant said: "He started shouting at me that he was going to stab me and bring his friends to the store.

"We couldn't calm him down. He became louder and more violent."

Store staff called the gardai [police] who said that Maguire continued to swear at them and at Halfords employees outside the store.

Maguire had pleaded not guilty, although his solicitor said that he accepted he had used “certain words” that he now regretted.

He added that his client was sorry for how he spoke to the sales assistant, which he said was because he felt his consumer rights were being infringed.

Judge Cormac Dunne imposed a €400 fine on Maguire and said he had inflicted "gratuitous and unjustified abuse" on the shop’s workers.

The judge said he believed Maguire has "some anger management problem."