Otley's Lizzie Armitstead narrowly missed out on making it a hat-trick of national road race titles when she had to settle for third place in south Wales.
Laura Trott claimed her first senior national title on the road by beating Wiggle Honda team-mate Dani King into second place in a sprint finish involving five riders.
Armitstead had appeared on course to win for the second year in succession after attacking around 20km from the finish and building up a lead of 17 seconds but she was caught by Trott, King, Emma Pooley and Sharon Laws in the closing kilometres as the race came down to a sprint finish.
Trott, 22, who also claims the under-23 title for the third time, was able to count on the support of King in the finishing straight and the pair crossed the line comfortably ahead of Armitstead.
Trott said: "It’s such an amazing feeling. It’s up there with winning a world championships for me.
"I was so, so up for it. I woke up this morning and I was like ‘don’t even speak to me’. It was really early, I was so in the zone, I just wanted to get out and get it done."
The race took place on a hilly 101km course starting and finishing in Abergavenny and the favourites for victory wasted little time in forming a 13-rider breakaway early in the day following an attack by Armitstead.
That group was later whittled down to eight, with the five who contested the finish being joined by Dame Sarah Storey, Katie Archibald and Elinor Barker.
Armitstead was determined to avoid a sprint finish and launched another attack with 20km to go but, although she built up a healthy advantage, she was unable to hold off a strong chase.
Armitstead said: "I'm disappointed. I had my normal issue of wanting to take the race on, so on every incline I gave it a go. I didn't want to take it to a sprint; for me, that was more of a risk than going solo."