MUR DE BRETAGNE, France

Sometimes in cycling the bike can be the rider’s biggest enemy.

Tour de France contenders Tom Dumoulin and Romain Bardet both lost significant time in the overall standings after spokes on their wheels snapped near the uphill end of Stage 6 on Thursday.

Both title hopefuls were left behind by the rest of the top riders as they increased the pace hunting for the win that finally went to Daniel Martin of Ireland.

Dumoulin said his bike broke when he knocked into Bardet near the foot of the second of two two-kilometer ascents up the Mur de Bretagne to the finish line.

Dumoulin and his Sunweb team compounded the mechanical mishap by getting a 20-second penalty when Dumoulin stayed too close to the team car while trying to catch the pack, thereby benefiting from its draft that pulled him along.

Dumoulin and Bardet entered the three-week race among the chosen few riders considered strong enough to challenge four-time champion Chris Froome.

Dumoulin, the time trial world champion and 2017 Giro d’Italia winner, started the stage 44 seconds ahead of Froome, but finished just behind him. Froome trails race leader Greg Van Avermaet by 1:02. Dumoulin is one more second behind.

Bardet was already trailing Froome, and after losing 28 seconds is now 1:45 off the leader’s pace after he broke his back wheel and had to change bikes with Tony Gallopin.