"These classes will race at the same time as the junior race and be 75 minutes' duration," said Clarke, the series organiser, who is also a former International Six Days Enduro medal winner and multi-time former national enduro champion.
"This is the fifth time I have run the series and each time it is getting bigger and bigger."
He said there were classes to cater for all ages and abilities with the senior grade split into two sections, for intermediate and expert riders. There are separate categories also for women and veteran riders.
The race for top senior honours in last season's Dirt Guide Cross Country Series was tight with three national class riders - Auckland's Callan May, Napier's John O'Dea and Tauranga's Reece Burgess - separated by just three points at the start of the final round.
Close racing is expected again this season.
The Kiwi Rider magazine-sponsored series has been a real hit with the country's off-road bike riders, with competitor numbers growing with each outing, and this weekend's event is no exception.
In addition to attracting full fields, the talent runs deep with many current or former national champions typically among those entered.
The junior race starts at 9.30am and the two-hour senior race starts at 12.30pm.
The minis' course will be about 3km in the forest, and the junior track is 10km, while the senior course is about 20km around.
The cross-country series is run parallel with but separate from the Dirt Guide Trail Ride Series, with that phase of the weekend's action set for the same venue the following day.
Sunday's trail ride will feature a 30km main loop or a 10km short loop option.
Calendar
(Trail ride on day two in each case):
Round one Tar Hill, Tokoroa, April 28-29.
Round two The Pylons, Atiamuri, May 19-20.
Round three Whakamaru, June 30-July 1.
