Police in Gloucestershire are warning that thieves may be targeting high-end bikes after a Cheltenham family suffered a theft in which mountain bikes worth a total of £20,000 were stolen from their garage.

The bikes taken included one worth £6,000 that 32-year-old Isabel Booth had handbuilt herself as an engagement present to her fiancé Rod, now her husband, and which he has never ridden due to injury.

Mrs Booth had worked on the bike, an Intense Tracer, at the workshop in the Cheltenham branch of Leisure Lakes bikes, reports This Is Gloucestershire.

"I spent months and months putting money aside to buy all the parts one bit at a time and then I went into the shop to make it myself," revealed Mrs Booth, a mother of three.

"I learned how to do it all in the workshop and they helped me to build it, so it was completely unique and can't be replaced."

The bike was one of six stolen on Saturday evening from the couple’s garage at their home in Cheltenham. All of the bikes were locked up.

Also stolen were three other bikes belonging to Mr Booth – a black Yeti SB-66 valued at £5,500, a carbon Lapierre Zesty 914 costing £5,250, and a red and black On-one 456 worth £2,250 – plus a red, white and black Specialised SSR Myka belonging to Mrs Booth worth £1,500, and her 12-year-old son Davey’s red Santa Cruz bike, worth £2,500.

According to This Is Gloucestershire, the value of the bikes meant that they could not be included on the couple’s household contents insurance policy, and no separate cover had been taken out for them.

Mrs Booth was in bed at the time the burglary took place, while Mr Booth was watching the Champions League Final. It is believed that the thieves forced the garage door open with a crowbar.

"I heard a bang at about 10.30pm, but it sounded like it was coming from the garden and I thought it was the dog running around," explained Mr Booth, who has twice before been the victim of bike theft in recent years.

"Back in 2009 I had bikes locked to a vehicle and went inside for a matter of minutes and when I came back they were gone," he explained.

"Then last Christmas Eve, a bike we bought Davey for his present was stolen, so we had to rush out to get another to replace it."

Scott Jones, worshop manager at Leisure Lakes Bikes Scott Jones, told This Is Gloucestershire: "For Isabel to build the bike was a really nice gesture. It was a pretty rare frame and nobody else would have had a bike like that. It's horrible to hear about this sort of thing."

Sergeant Tony Wallace of Gloucestershire Police commented: "The officers in Hester's Way [a suburb on the western edge of Cheltenham] have reported an increase in high-value bike thefts."

Anyone with information regarding the crime is asked to contact Gloucestershire Police on 101, quoting 114 of May 20.