Being "bored" on the last climb of the Pic de Nore, he attacked out of the Team Sky-led peloton, spending about 35km out in front before being caught on the descent.
"Yesterday was kind of that reset button again, just to go out and enjoy it again," Martin said while cooling down on his turbo trainer.
"I was kind of bored on that last climb. It looked like LottoNL-Jumbo and Sky were content on riding really slow up the climb, so I thought why not see how far they'll let me go."
The escape stayed free today as Magnus Cort Nielsen (Astana) won the stage. Martin, 10th overall, rode away over the top of the Pic de Nore climb and solo down the other side.
However the descent towards Carcassone was not as fast as he had thought and the television motorbike stuck with the peloton, instead of offering Martin that extra bit of needed draft.
"I was thinking how nice it was not to ride with those other guys. It was nice to be on the downhill alone, but I had to pedal the whole way. I'd expected it to be a lot more downhill," Martin said.
Watch: Tour de France 2018 stage 15 highlights
"I don't know what the draft is, but obviously if you [the TV motorbike] are too far in front you can't see the riders on TV. It's a fact of our sport, but it does prevent attacking. Everyone wonders why no one attacks. What I did today was a perfect example, it's a waste of energy almost. It's not a waste of energy when you are having fun."
Martin enjoyed early success in the 2018 Tour with a stage win at the Mûr de Bretagne on stage six. He had to hit the reset button after crashing in stage eight and again on stage 14 on Saturday, puncturing at the foot of the uphill finish to Mende's airstrip.
"It's been up and down, yesterday again, I set the reset and decided to just go and enjoy myself, that's what I did today."
Martin finished sixth overall in the 2017 Tour, which was amazing considering scans after the race showed he had suffered fractured vertebrae in a crash on stage nine. He sits 10th overall now, at 6-54 behind leader Geraint Thomas (Team Sky) with the rest day and final mountain stages to come.
"There's no target, I am just enjoying each day and I hope I have those legs in the Pyrenees. I felt good all day. I tried to get into an escape or two but Sky would not have it."
Thank you for reading 5 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1
Gregor Brown is an experienced cycling journalist, based in Florence, Italy. He has covered races all over the world for over a decade - following the Giro, Tour de France, and every major race since 2006. His love of cycling began with freestyle and BMX, before the 1998 Tour de France led him to a deep appreciation of the road racing season.
Kristen Faulkner cools down after making a splash at the Giro Donne
The American headed straight for the sea to after winning the stage and taking the Giro Donne overall lead
By Owen Rogers • Published
Tour de France: Stage one time trial start times
All the start times for the opening stage
By Tom Thewlis • Published