EMMA Guy knows all about the school of hard knocks. It goes with the territory as a downhill rider in Britain's fastest-growing sport, mountain biking.

Last year just before the start of the racing season the 27-year-old from Lanark broke a collar bone while training in the forest near Innerleithen. She needed an operation to put a plate in her shoulder, but within a fortnight was back on her turbo trainer at home. She showed true grit and determination by taking part in the final two races of the national downhill series, winning one and coming second in the other.

That spirit, which typifies many of the combatants in mountain biking, did not go unnoticed and Emma, winner of the six-race national downhill and cross country series in 1995, was approached by Team Raleigh, Britain's biggest racing outfit.

They made her an offer and as Emma says: ''It was like a dream come true, the chance to be a full-time professional and travel all over the world in competition. It has made a tremendous difference to my life, relieving the financial worries and having proper coaching and working to a plan.''

This year she has been racing in World Cup events in South Africa and Canada and the British series when she can fit it in. Next stop is Italy and then France.

''I love the travelling, seeing the world,'' she enthused. ''We train hard, five hours a day. I am still learning, it's very technical in downhill. I'm confident I can get into the top-10 ratings in the world.''

It is a remarkable achievement for a girl who took up racing four years ago. ''I was a newcomer in 1994 and didn't have a proper bike. My first race was a cross country event in Dundee and I was so unfit I was pushing my bike up and downhill, but I won.''

The next year she saved up for a new bike. ''I was broke but I had three part-time jobs - in a bike shop, a wine bar and Edinburgh University laboratory,'' she added.

''I teamed up with some boys in the Edinburgh Bike Co-op and started going out training with them. I also joined a club in Penicuik where I had gone to school.

''I was all over the place, no strict regime. I was doing swimming and running and riding the bike.''

In 1996, Emma won the British four-race national dual slalom event - just like ski-ing except you are on a bike. She made the UK national squad and was selected for the world championships in Australia. Things were looking up and an engineering firm sponsored her. She wore their name on her racing jersey all year, but in the end got no money from the firm.

''I was naive and this experience shattered me,'' she said ruefully. ''I had little money and needed to raise #700 for my fare to Australia and cash to pay for accommodation and food.

''I sold all my worldly possessions, my camera, moved out of a flat and went back to stay with my parents in Edinburgh to save money. I was disillusioned with the sponsorship experience, but I was determined to get to Australia, which I did.''

Last year she rode semi-professional for Animal-Giant, then came her training injury which disrupted her season. ''It was a nightmare experience,'' she remembered. ''I was riding along in the forest then I heard this crack, it was my collarbone going.

''I felt nausea, but managed to push my bike back to my van and someone got a doctor. Still, I have been fine since the operation.''

Emma loves mountain biking and her joy of being a professional shines through, blanking out the ups and downs of the past. ''It's a great sport, with a big social side to it, at local or national level. After the competition riders go for a drink. I think we mix more than the other areas of cycling.''

She's helping to put something back into the sport by encouraging young people to take up cycling. ''My flatmate Tracy Brunger (a cross country elite rider with US team K2) and I have been making a video with the British Cycling Federation to take cycling to the schools. Every kid has a bike, there's a great chance for them to join in the revolution, cycling that is. It's so healthy.

''Just think, Britain is the world leader in BMX riding - no other area of British sport can say that.''

What does Emma think of people who say that mountain bikes should be kept off mountains? ''There's room for everybody. We have a code of conduct and are aware of other users whether walkers or horse riders. And we always keep to marked paths. When we see walkers we slow down and give them space. I think there's more damage done to the countryside by the number of boots walking on the mountainsides and forest trails.''

And that's downright honesty from a downhill rider.

Emma has more than one brush to her palette; she has an honours degree in fine art and would like to work on the design side for Raleigh. ''The sport is changing fast, with new ideas and new materials in outdoor wear, T-shirts and race jerseys,'' she said.

When she has some leisure time for herself she takes off on her Yamaha 250 motorbike for a spin up the west coast of Scotland.

Have bike - will travel could well be Emma's motto.