Anybody who stumbled into Gastown for the last lap of the women’s event in the famed Grand Prix over the cobblestone streets had to wonder what was going on at the finish.

As the pack came across the line on Water St., one woman near the back had her arms raised in glory, a big smile across her face.

No, Denise Ramsden wasn’t celebrating a 50th-place finish. The Vancouver resident who grew up in Yellowknife, NWT, had actually lapped a few of the riders, blowing away a strong field of 86 on Wednesday with a stunningly dominant performance.

The 25-year-old Ramsden, the 2012 Canadian road race champion, began a one-rider breakaway 10 laps into the 35-lap race on a 1.3-kilometre circuit of Water and Cordova.

“It was pretty early, so I was trying to temper my effort a little bit and make sure I could kind of ramp it up at the end more when I knew the girls would be going hard,” said a beaming Ramsden.

“So that far out you never know, but I was willing to give it shot.”

It was like she was shot out of a cannon.

Two laps later, the Trek Red Truck Racing team rider had a 23-second lead. She built the gap to 26, then 30 and up to 48 and 55 seconds. With the crowd of several thousand hanging four-and-five deep behind the barriers and cheering her loudly, the announcers put a couple of primes together to offer a $400 incentive if she could catch the pack. She did it with two laps to go.

“A couple of teammates in the pits were saying ‘Okay, you can do it, you can do it’ so I had a little bit more energy there at the end for that,” said Ramsden.

Ramsden said there was no particular plan with the Trek Red Truck squad to send somebody out on an early breakaway.

“My mom was in surgery all day, so I actually missed the team meeting and didn’t get here to about 5:30 (p.m.),” said a laughing Ramsden of her arrival about 45 minutes before the start the race.

“So (teammate) Leah (Guloien) and I talked about actually trying to be a little bit less aggressive and follow moves, but the moment came and it seemed like a good time to go.”

Ramsden said she had felt “absolutely awful” Tuesday night at the UBC Grand Prix, but she made up for it with as dominant a women’s ride as the Global Relay Gastown Grand Prix has ever seen.

Earning a cool $12,000 for the win – the largest for a criterium in North America -- Ramsden finished 30 seconds ahead of second-place Annie Foreman-Mackey (The Cyclery-Opus) of Kingston, Ont. American veteran Shelley Olds (Ale-Cipollini) was third, hitting the podium for the fifth time in five BC Superweek races in 2015.

“Denise Ramsden is an incredibly strong rider and we know that,” said Olds, a Gilroy, Calif., resident. “I was trying to tell the girls (in the pack) when she was going that we can’t let her go. She’ll take the lap.”

Ramsden, who was 19th in the time trial and 27th in the road race at the 2012 Olympian, is headed to UBC law school in September.

“We’ll see (where the 2016 Games fits in), but I still love racing and I’m sure I’ll still be riding,” she said.

(bullet) Ryan Roth, a 32-year-old Guelph, Ont., product racing for Quebec-based Silber Pro Cycling, won the 65-lap men’s race, pulling away from an eight-man breakaway in the final few laps to beat H&R Block Pro Racing’s Garrett McLeod to the finish line by five seconds.

Will Routley of Langley and Optum/Kelly Benefits Strategies was third.

“Kind of surprising, I guess,” Roth said of his win. “I didn’t start the day thinking I would be one of the favorites to win, so I’m really, really happy.”

Silber manager Gord Fraser, a two-time Gastown winner, called Roth’s win “an incredible performance.”

“Ryan’s just such an incredible leader of the team. He’s kind of a sleeper in Canadian cycling. There’s a lot of guys getting a lot of ink. Ryan just produces time in and time out. He’s the most consistent rider we have in Canada. To see him win tonight was just a real pleasure for me.”

gkingston@vancouversun.com