After a couple of laps, the lead group was down to a bunch of 14 riders who remained intact for the rest of the race.
The main action up front came from Tom Francis fresh from competing in the elite road nationals in Christchurch last weekend.
He broke clear regularly but wasn't able to attract anyone strong enough to go with him to make a breakaway stick.
Bismark was less active, but still did his share of the work, while Phil Groves, Richard Stanton, Adrian Petit, Shaun Tucker and Jason Sturzaker were all regular contributors to the group effort.
Hayley Giddens, back from a successful North American campaign in 2012, was also well in the mix.
She sets off overseas again in a month's time to re-join her Wisconsin-based professional road team.
Former elite track rider Cherie Prince rode strongly early on and although she dropped back after lap two, she will be competitive in handicapped events later in the season.
On the final lap Bismark and Francis attacked entering the corner onto Eastown Road and it took a desperate effort by Groves to scramble across to them leaving the remaining 11 riders in the front group about two seconds behind them and chasing hard with a kilometre to travel.
In the long finishing straight on Eastown road the chasers put in a concerted effort to run down the front three. But with the wind behind them and Francis and Bismark riding flat out the gap was unable to be closed.
In the last few metres Bismark, in excellent physical condition and riding a brand new bike, edged ahead to win by an official margin of a second.
Francis held off Groves to claim a deserved second placing, the latter in turn having enough in reserve to finish just in front of the charging bunch behind.
Sturzaker produced a tidy effort to finish fourth, narrowly ahead of Steve Cowan, with youngster Lewis Bunker doing well for sixth after struggling with the pace for a lot of the race.
He could be in for a big year.
The dedicated Debbie Cain was rewarded with a sprint-finish victory in the battle for C-grade honours over two laps (18km) of the same course.
The C-grade race was also run as a mass start event and by the turn off on the first lap at Kaimatira Road onto State Highway 3 Cain, Dean Blackwell and Alison Richards had broken clear of the other eight competitors.
They combined well for the remainder of the race, riding strongly in the wind to stay clear of the field and fight out the finish.
In the dash for the line it was Cain who showed great tenacity to hold off the late lunge from Richards and claim the win.
Cain is an enthusiastic competitor who fronts up week-in, week- out often sacrificing her own chances by assisting new riders so her win was well received.
Richards, who was having her first race in four and a half years, put in a great effort for her placing.
Results
A and B Grade
1. Brent Bismark (fastest time 56.54); 2. Tom Francis; 3. Phil Groves.
C Grade
1. Debbie Cain (fastest time 35.15); 2. Alison Richards; 3. Dean Blackwell.
