Kristin Armstrong is back in the Olympics — back on her bike chasing gold after retirement and motherhood and injury, back where she told others she would never be again.

Armstrong is back to defend her 2008 gold medal in the women’s cycling time trial. Back to prove that motherhood doesn’t mean an end to an athletic career. Back to try to create a memory that her young son will remember.

Back for what she promises — and she really means it this time — is her last Summer Games.

“I’m a hypocrite. I told myself and others many times prior to having (her son) Lucas that there was no way I was going to go back to something about myself again,” Armstrong said earlier this month before leaving for London. “The question of why? When it gets down to it, when I left the sport, I wasn’t tired of the sport. I wasn’t tired of the competition.”

And so she is back.

The 38-year-old Armstrong, a University of Idaho graduate and Boise resident, is competing in her third Olympics. She will compete in the women’s road race Sunday and then in her signature event, the time trial, on Wednesday.

Armstrong left professional cycling after winning the 2009 world championships. She was ready to start a family with her husband, Joe Savola. She gave birth to Lucas in September 2010.

It wasn’t long before Armstrong and Savola began plotting a path back to the Olympics.

“I knew I had about 20 months until London. It might be an attainable goal,” she said. “It might be a fun thing.”

With plenty of help from her family — and with the flexibility that a training schedule provides — Armstrong has been able to balance motherhood and cycling. But regaining the form she had just a few years earlier proved difficult, particularly for a strong-willed and driven athlete.

It wasn’t as easy as just getting back on the bike, and Armstrong struggled in 2011.

“I was starting to believe that maybe things weren’t supposed to happen,” she said. “Of course, people told me, you had a baby and tried to race five months later and expected to be on top in month six.”

It took a little longer than she wanted, but Armstrong regained her form this year. After a month of training in California in February, she had a dominant spring season, showing that she was a candidate for the U.S. Olympic team and a real contender for the gold.

Armstrong won every time trial she competed in going into May’s Exergy Tour in Idaho. The event, sponsored by Armstrong’s team sponsor, was supposed to be the finishing touch — the exclamation point on her path to London.

Instead, Armstrong crashed in the prologue, breaking her left clavicle and briefly casting doubt on her chances to be in London.

A defiant Armstrong finished the stage, had surgery the next morning and showed up at the race the next day to support her teammates — and demonstrate to the selection committee that she would be just fine. Armstrong even called out media members for creating any bit of doubt about her readiness.

“Anytime things do down the wrong path, you can embrace them or go down that wrong path as well,” she said. “I had to look at all the positives. Sometimes you can’t even think of the positives before it happened.

“Once I had surgery and knew everything was going to be OK, I did look back and it did allow me to refocus. I got used to things that were going really smoothly. There weren’t any hurdles, wasn’t any reason to refocus. It made me refocus and work harder.”

Despite the injury, Armstrong was chosen as one of two Americans to compete in the time trial. She spent her rehab training on the bike and focused on the event, making sure she retained as much of her fitness as possible.

Last week, Armstrong returned to racing, winning the first three stages of the Cascade Cycling Classic, including the time trial. She withdrew from the race before the criterium. Armstrong also competed in the CCC before the 2008 Summer Games.

“You can do a lot by yourself, but there comes a certain point where you need other people to push you. It’s the last tune-up to top my training off,” Armstrong said.

All that’s left is England. Twelve family members, including Lucas, will be with her at the Games. Armstrong skipped Friday’s Opening Ceremony to focus on her events.

She has just one goal.

“I don’t want anything less than gold. It’d be one thing if I got silver or bronze the last time around. One more higher medal would be good,” said Armstrong, who turns 39 on Aug. 11. “It’s hard going in as defending champion and thinking you want anything less than a win.”

This is why she came back.

Brian Murphy: 377-6444,Twitter: @MurphsTurph