Stage 12 of the 2013 Giro d'Italia was contested on 16 May, and the race concluded on 26 May. The second half of the race was almost entirely situated within Italy; it started with a categorised flat stage from Longarone to Treviso, before four mountain stages – as well as a mountainous individual time trial between Mori and Polsa – en route to the finish in Brescia, where the race concluded with a road stage for the first time since 2007. The race also crossed over into France during the fifteenth stage, ending with a summit finish on the Col du Galibier. After the second rest day of the race, the peloton returned to Italy in the following stage, from Valloire in France to Ivrea.
Having picked up the overall race lead after the eighth stage, rider Vincenzo Nibali was able to hold onto the race leadership for the entire second half of the Giro, and as a result, achieved the second Grand Tour general classification victory of his career; he had previously won the 2010 Vuelta a España for the team. Nibali held a 41-second lead margin over 's Cadel Evans until the fourteenth stage, when Nibali attacked on the final climb to the Monte Jafferau outside Bardonecchia, and was able to gain 45 seconds on Evans by finishing second to 's Mauro Santambrogio. Nibali later won two stages during the final week of the race, further extending his overall advantage, and eventually completed the race with a winning margin of close to five minutes. Evans was unable to hold onto second place overall, as he faded on the final climb of the race to Tre Cime di Lavaredo; he ultimately finished third overall behind rider Rigoberto Urán, who had become his squad's leader after Bradley Wiggins was forced to withdraw.
Aside from the overall race battle, Mark Cavendish was able to avenge his close defeat in the points classification at the 2012 race – where he lost the red jersey by a single point to rider Joaquim Rodríguez – by taking the classification on the final day in Brescia. The rider's victory in Brescia, his fifth of the race – he achieved three in the second half of the race, with other victories on stages 12 and 13 – allowed him to become only the fifth rider to complete a clean sweep of points classification victories at Grand Tours. Giovanni Visconti was another rider to take multiple victories during the second half of the race, taking solo victories at the Col du Galibier and into Vicenza. The second half of the race was also adversely affected by snow, with three stages being re-routed and a fourth having to be cancelled due to heavy snow and treacherous conditions; the cancelled stage was the first due to weather since the 1989 Giro d'Italia.
LegendJerseys appearing in the table on the left of the page indicate those worn by the cyclist during the particular stage, while those appearing in the table on the right of the page indicate those awarded to the cyclist after the stage. Denotes the leader of the General classification Denotes the leader of the Mountains classification Denotes the leader of the Points classification Denotes the leader of the Young rider classification s.t. indicates that the rider crossed the finish line in the same group as the one receiving the time above him, and was therefore credited with the same finishing time.
Stage 12 16 May 2013 — Longarone to Treviso,
The second half of the race started with a stage ideally favoured towards the sprinters; with a parcours of – one of the shortest of the race – the stage was predominantly downhill from the start in Longarone, all the way to the finish in Treviso. Along the course, there were two fourth-category climbs alternating with the two intermediate sprint points – coming in the comunes of Pieve d'Alpago and Vidor respectively – within the opening two-thirds of the stage. The two categorised climbs were short and punchy; the Muro di Cà del Poggio averaged 12.2% over , while the Montello-Santa Maria della Vittoria ascented at an average of 6.3% over . Once the riders reached Treviso, they completed a loop around the city; the final metres involved the crossing of a bridge, before the line on the Viale Bartolomeo Burchiellati.
Wet conditions awaited the riders in Longarone, where the breakaway was initiated almost immediately after the start, with a four-rider move going clear. The breakaway was made up of ninth stage winner Maxim Belkov (), rider Fabio Felline, Bert De Backer of and 's Maurits Lammertink. Lammertink's team-mate Marco Marcato bridged the gap not long after, to make it a quintet. With a lead of nearly three-and-a-half minutes, all bar De Backer fell in the treacherous conditions, but were able to get back on their bikes not long after. The sprinters' teams slowly brought the lead group back, holding a 25-second lead going into the final loop around Treviso; the quintet managed to hold off until inside the final kilometre.
From there, the lead-out train swooped to the front, with Gert Steegmans providing the perfect launch for Mark Cavendish to take his third stage win of the race, and what was to be the 100th win of his professional career. 's Vincenzo Nibali maintained his 41-second overall lead ahead of the 's Cadel Evans. Further behind, rider Bradley Wiggins suffered the most notable time loss during the stage. With no fewer than four team-mates around him, Wiggins lost 3' 17" on the day to the main group, falling out of the top ten overall. Wiggins attributed his lack of performance to an ever-worsening medical ailment; he had been taking antibiotics due to him suffering from a cold and chest infection. Due to this, general manager Dave Brailsford stated that the team would now be backing Rigoberto Urán, lying third overall, as their best hope of winning the race.
Stage 12 result RiderTeamTime 1 2 s.t. 3 s.t. 4 s.t. 5 s.t. 6 s.t. 7 s.t. 8 s.t. 9 s.t. 10 s.t.General classification after stage 12 RiderTeamTime 1 2 + 41" 3 + 2' 04" 4 + 2' 12" 5 + 2' 13" 6 + 2' 55" 7 + 3' 35" 8 + 4' 05" 9 + 4' 17" 10 + 4' 21"
Stage 13 17 May 2013 — Busseto to Cherasco,
At , the thirteenth stage was also the longest stage of the 2013 Giro d'Italia. The parcours, which ran through six different regions, was flat from the start to around the point. From there, there were several uncategorised hills on the route, passing through the two intermediate sprint points – which were competed at the comunes of Castagnole delle Lanze and Alba respectively – before reaching the day's only categorised climb. The third-category Tre Cuni was seen as a potential danger for the sprinters – ahead of the finish in Cherasco – with a gradual rolling climb of around 5% over . From there, the riders descended towards the finish with several rolling hills in between; the expectations were still there for a sprint finish, but not a certainty. Prior to the start of the stage, former contenders for the overall classification, Bradley Wiggins () and Ryder Hesjedal () both withdrew from the race.
A seven-rider group broke away from the peloton after around of racing, and with no potential contenders for the overall classification, the main field allowed the breakaway members to build up a lead of almost fourteen minutes at one point during the stage. With the main contenders unwilling to pull the gap back, it was left to the teams of the sprinters to set the pace; they did so gradually, with the leaders holding an advantage of just over a minute before the climb to Tre Cuni, around from the finish. On the climb, 's Nicola Boem initiated the first attack, and was joined by Pablo Lastras of the and Lars Bak (), with the trio pulling clear of the remaining four members of the lead group. A small group attacked the peloton behind, but after several kilometres off the front of the bunch, this group was pulled back, leaving the three leaders around thirty seconds clear.
– looking to set up Mark Cavendish for a fourth stage win at the race – were stationed at the front of the peloton, and slowed the pace of the chase, and allowed the lead trio to gain several seconds of an advantage, pushing the lead out to almost a minute. Boem was dropped shortly after, while Lastras and Bak were joined by another group of riders, with seven going clear from the peloton. From the group, Giampaolo Caruso () attacked with remaining, but his solo bid for victory was stopped with left. led the field into the final kilometre for Elia Viviani, but Cavendish was first to launch his sprint, and was able to hold off the rest, just edging out Giacomo Nizzolo of on the line. With his fourth victory of the race, Cavendish became the sixth rider to win 40 Grand Tour stages, and the first rider to take successive Giro stages since Alessandro Petacchi in 2009.
Stage 13 result RiderTeamTime 1 2 s.t. 3 s.t. 4 s.t. 5 s.t. 6 s.t. 7 s.t. 8 s.t. 9 s.t. 10 s.t.General classification after stage 13 RiderTeamTime 1 2 + 41" 3 + 2' 04" 4 + 2' 12" 5 + 2' 13" 6 + 2' 55" 7 + 3' 35" 8 + 4' 05" 9 + 4' 17" 10 + 4' 21"
Stage 14 18 May 2013 — Cervere to Bardonecchia,
Originally due to be held over a parcours of , the fourteenth stage was altered on the morning of the stage, due to bad weather, which also precluded televised live pictures of the race for all but the final few hundred metres. The originally-scheduled climb to Sestriere, a second-category gradual ascent, was removed from the itinerary, with the peloton being re-routed along roads in the Susa Valley to Oulx. The race rejoined the original itinerary at Oulx; in total, was added to the stage distance. From there, the parcours rose to steadily to an intermediate sprint at Bardonecchia, before the climb to the finish on the Jafferau. A first-category climb for its third appearance in the Giro, the Jafferau averaged a 9% gradient over , with places reaching 14% and portions of the climb being run on unsurfaced roads.
A group of seven riders went clear after around of racing, but this was quickly reduced to four, as three riders fell on wet roads. When they had recovered to the main field, the lead group started to increase their advantage. The all-Italian group – former race leader Luca Paolini (), Daniele Pietropolli of , rider Sonny Colbrelli and 's Matteo Trentin – were able to extend their advantage to almost ten minutes at one point before the peloton started to bring them back. As the race moved towards the Jafferau, took up station on the front of the peloton, slimming the numbers in the main group. Before the final climb, Trentin was dropped by his three companions, and was soon caught by the main field on the climb.
The leaders held a lead of around four minutes at the foot, at which point, Colbrelli attacked. Only Paolini could stay with him, as they set about trying to hold off the front. Sergio Henao () attacked halfway up the climb, where he was joined by Diego Rosa of ; Rosa's move was the precursor of an attack by his team captain Franco Pellizotti. Pellizotti caught the duo, and soon set off alone after the leaders, pulling within two minutes before being caught. Paolini dropped Colbrelli with around remaining, and held a 43-second lead over the fast-closing chasers. After Paolini was caught, maglia rosa wearer Vincenzo Nibali attacked for , pulling 's Mauro Santambrogio with him. The two remained clear until the end, with Santambrogio taking the stage win, his first in a Grand Tour. Nibali finished close behind, to extend his overall lead to 1' 26" over 's Cadel Evans, with Santambrogio moving into fourth overall, one second behind Rigoberto Urán of .
Stage 14 result RiderTeamTime 1 2 s.t. 3 + 9" 4 + 26" 5 + 30" 6 + 33" 7 s.t. 8 s.t. 9 + 55" 10 + 58"General classification after stage 14 RiderTeamTime 1 2 + 1' 26" 3 + 2' 46" 4 + 2' 47" 5 + 3' 53" 6 + 4' 55" 7 + 5' 02" 8 + 5' 32" 9 + 5' 39" 10 + 5' 41"
Stage 15 19 May 2013 — Cesana Torinese to Les Granges du Galibier (France),