Sam Cook powered to a personal best in Cwmcarn Paragon’s 10ml time trial on the R10/59 circuit in sweltering conditions.
He clocked a superb 21min 12sec to beat brother Harry by 1min 6sec – just four seconds had separated the pair the previous week – in the open TT bike category during the June 25 event.
Paragon club secretary Matt O’Brien capped a busy nine days of racing by finishing third in 24:02.
O’Brien had finished eighth in a crit road race at Llandow on his road bike, but confessed to suffering his worst day of pedalling at the unrelenting Welsh Gravel Championships last weekend.
Paralympic women’s TT competitor Julie Hooper finished in 26:16 while Ross Porter topped the open road bike category in 26:10.