Ireland's toughest sporting event? Some will dispute the superlative, but this is unquestionably a masochist's paradise.

Tomorrow, at 12.30 in O'Connell Street, the flag drops to signal the start of the 47th FBD Milk Ras, a nine-day, 1,280-kilometre test of endurance, strength and resolve around the roads of Ireland.

Imagine four hours a day of frantic, all-out racing; a 25-m.p.h., caution-to-the wind, rule-book-out-the-window state of affairs. Throw in 20 categorised climbs, some of the heaviest, most exposed roads in Ireland and the dual gremlins of wind and pouring rain and you get the idea. In effect, a marathon every day for nine days. Little wonder then that completing the race, becoming a "Man of the Ras", is a badge of honour in Irish cycling.

First held in 1953, the current edition of the Ras looks set to be the biggest in the history of the round-Ireland race with almost 200 cyclists set to take part.

The international line-up is impressive, too: in addition to previously confirmed squads from the Netherlands and Germany, the field is bolstered by one Estonian side, a Sweden-Finland composite, a Belgian quintet and two teams from the US. Besides these challengers from Europe and America, nine squads travel across the Irish Sea vying to secure the first foreign victory since Dainis Ozoles in 1989, and only the second from Britain.

Six English, one Welsh and two Scottish teams line out tomorrow, and they are considered a serious threat, with riders such as Mark Lovatt, Wayne Randle, Gethin Butler, former king of the hills Jeff Wright and English national road race champion John Tanner.

Of the home riders, last year's victor, Philip Cassidy, leads the challenge and is attempting to become only the third cyclist to successfully defend the title. Cassidy has been in dominant form all season, but has been conspicuous by his absence from the results in the past two weeks.

Burnt-out, or bluffing? Most likely the latter, but should the 38year-old falter, his Ireland teammates Tommy Evans, Eugene Moriarty, Bill Moore and Fergus McCauley are capable of stirring things up. So too David McCann, regarded by some as a hot favourite following international success this season. Among the others likely to figure are Aidan Duff, Patrick Moriarty, David O'Loughlin, Brian Kenneally, Eddie O'Donoghue, Dermot Finnegan and last Sunday's Shay Elliot memorial winner, Stephen O'Sullivan. As for the route, 1955 winner Gene Mangan describes it as "not really one for the pure climbers, but one which will be a very fast Ras. These," he says, "are the hardest as it is flat-out day after day."

Mangan pinpoints Stage Two to Newport, the 192 km stage to Listowel; Stage Five (which brings the riders into the mountains of the ring of Kerry) to Kenmare; Stage Six to Mitchelstown, and the penultimate day's racing through the Wicklow mountains to Tullow as the most difficult.

The latter stage is also the last real chance for a change in the overall classification, for, dramatic and entertaining as the Dublin city centre criterium is, the overall winner of the 2000 Ras will almost certainly have been decided.