Carpenter pushed on to finish 33 seconds ahead of Ethan Hayter and Alex Peters to take the lead in the general classification, with a lead of 22 seconds over Wout Van Aert.
“In the end leading the overall is great and it’s a big bonus but we’ll see about making it through the team time trial tomorrow with my team-mates,” Carpenter said.
“We were going to hit it hard anyway. We’ve got a couple of guys who are well suited to maybe go for the overall so we’ll do our best and we’ll see what happens but it’s going to be a challenge for sure.”
Stage three will see a team time trial over 18.2km, which starts in Llandeilo and heads to the National Botanic Garden of Wales on Tuesday.