She hopes to complete the double when she tackles her road race in the championships on the Matapiro Rd circuit tomorrow.
Tunnicliffe, who has lived in Hawke's Bay for 10 years, started riding 20 years ago when her son raced for Auckland Grammar.
The Bay's other gold medal winners were Ingrid Perols in the masters four age group and Regan Gough in the under-17 boys grade.
In the past two years Perols won silvers in the time trial. Her 15km time yesterday was 42m 07s. Central Hawke's Bay's Gough won his 15km event in 22m40s.
Successful Hawke's Bay coach Ivar Hopman's smile was just as big as those of Gough, Tunnicliffe and Perols last night.
Hopman, who runs Team Coach, had three medal winners in Gough, Ramblers' Craig Hill, who won bronze over 25km in yesterday's paracycling division, and Ian Seddon who won bronze in the masters five division event over 25km.
Other Bay medal winners were Andrew Townsend with silver in the master three 25km event and Sam Thorpe-Loversuch with a silver in the under-15 boys 15km event.
Event director Gavin Bush said the time trials went well.
"The weather was nice and although the competitors found the course challenging some good times were posted."
Sam Horgan of Pegasus Cycling Incorporated retained his elite men's title with a time of 53m03s over 40km. Wellingtonian Andrew Hagan was second in 56m14s.
Te Awamutu's Olympic team member Jaime Nielsen won the elite women's event over 25km in 36m50s from another Waikato rider Sarah Morrison.
There was plenty of attention in the elite women's contest with the Olympic-bound pursuit group of Nielsen, Rushlee Buchanan, Lauren Ellis and individual pursuit world champion Alison Shanks competing.
Nielsen was pleased with her strong performance while Buchanan finished third, Shanks fourth and Ellis seventh.
"It was a fun course. The sun showed up so it was fantastic," Nielsen said. "It was a great start for me. The course had a lot of texture in it although that hill on the way back was a bit nasty once you had some hurt in the legs.
"It's fantastic to have the whole team here and great to see so many people taking part and watching."