By Richard Petrie BBC Sport

Joey Dunlop was a hero at the Isle of Man TT

The past few days have continued to highlight the highs and lows of the world famous Isle of Man TT Races.

Practice was delayed on Monday evening after Seamus Greene and Jun Maeda were seriously injured in an incident near the Union Mills section, once again casting a shadow over the first week of the event.

Many will feel that racing high powered motorcycles on public roads is now too dangerous an occupation, especially in an age where health and safety considerations seem to be creeping into seemingly mundane areas of everyday life.

Legislators, especially those in Europe, may pose a threat to the future of the TT but in the meantime bikers from across the globe will continue to take up the challenge of this gruelling circuit.

For them, it is their Everest, an adrenalin buzz and a high speed thrill that they cannot get anywhere else.

That's why so many racers come back year after year to pit their skills, display their courage and set themselves personal targets with full knowledge and appreciation of the risks involved.

The variety and length of the TT course is unique in the racing world and for visiting holiday motorcyclists it gives them the chance to ride the same tarmac as that of the heroes they love watching from the walls and hedges around the course.

For spectators too, the Manx course offers the most spectacular vantage points, with machines often blasting past at high speed just feet away from the best viewing spots.

Until recent years a notable feature of the first week on the island was the early morning practices

Popular areas like Creg Ny Baa, Hillberry, Rhencullen and the Gooseneck will not be experienced anywhere else.

Predictably, practice is being dominated by the likes of John McGuinness, Guy Martin and Bruce Anstey but it is the many privateer riders on very limited budgets who help make the event what it is.

The races would not be the same if it was only the top 20 riders circulating into view every 20 minutes or so.

Over the years, the star riders have adopted a different approach to practice week.

With the TT being a time trial and riders starting at 10 second intervals, there are no grid positions at stake and while some are determined to make their presence felt and stretch their machinery to the limit, others are inclined not to show their hand until race day.

Steve Hislop was among those who set sizzling times in practice, akin to his race speed, but canny Ulsterman Joey Dunlop almost always upped his pace from practicing to racing.

Until recent years, another notable feature of the first week on the island was the early morning practices, in which roads closed at 5.00am and the bikes were on the circuit at 5.15am.

This long standing tradition ended after 2003 and all practices are now held in the evening, with the exception of Thursday afternoon.