The female bikers heading to the top of the world

The border on the road from Syabrubesi in Nepal to New Tingri in Tibet

As road trips go, a group of British adventurers are about to put Thelma and Louise well and truly in the shade.

Steph Jeavons, 44, from Gwynedd, is to lead the first all-female motorcyclist group to Everest base camp.

The 24-strong group, raising money for charities and good causes, will ride to an altitude of 17,000ft (5,200m)

Along the 1,500-mile (2,400km) route, they will tackle narrow dirt roads, stomach-turning drops, extreme weather and altitude sickness.

Riders will walk the last kilometre to base camp

Steph, who is from Llanberis at the foot of Wales' highest peak Snowdon, is no stranger to taking on mammoth challenges. Last year she became the first Briton to circumnavigate the globe on a motorbike and ride on all seven continents, including Antarctica.

Having travelled solo around the world, now she is leading a group of female riders from the UK, Germany, USA and Australia to the world's highest mountain.

"It's going to be a massive effort for everyone. Most of the women have never ridden outside of their own country let alone anywhere like this," she said.

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"The biggest challenge will be their confidence. Often women don't do these extreme adventures because they lack the confidence rather than any ability. They're worried they will hold people back.

"I'm sure there will drama along the way, bumps, tears and people questioning why on earth they signed up.

"But the fact that there are no men means these women are going to have to do plenty for themselves and I know what they will get out of at the end. That's my motivation."

Countless switchbacks on the Himalyan roads

Mount Everest base camp checkpoint

Among the international group are Sam Vernon and Amanda Hynan from Lincolnshire, Amy Harris from Bristol, Paula Hockey of Colchester, Essex and Janet Peter from Congleton, Cheshire.

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Julie Charlton, of West Woodburn, Northumberland, Emma Haynes from Winchester, Hampshire, and Dani Fiddaman, of Wantage, Oxfordshire, are also riding.

It has taken two years of planning since The Friendship Highway through the Himalayas was reopened after it was damaged in the devastating April 2015 earthquake that killed almost 9,000 people.

Starting on Sunday in Kathmandu, Nepal, they will ride for two weeks on Royal Enfield bikes through Nepal, into China and up through the towering peaks of Tibet to base camp.

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As well as mountain passes and glaciers, Steph admits the mental challenge will be as tough as the physical.

"There are some very high mountain passes on narrow paths with pretty big drops," she said.

"The roads themselves shouldn't be too bad but the sight of the drops is a psychological battle.

"Anything can happen at those heights, such as landslides or snow, and parts of the route could break up. However I'm probably just as worried about negotiating the traffic coming out of Kathmandu!"