Stage 12 of the 2012 Vuelta a España was contested on 30 August, and the race concluded with Stage 21 on 9 September. The second half of the race was situated entirely within Spain; starting with a medium mountain stage from Vilagarcía de Arousa to the Mirador de Ézaro in Dumbría, before four summit finishes and, ultimately, the customary race-concluding ride into Madrid.
Having held the lead of the Vuelta since the fourth stage, Joaquim Rodríguez of maintained his lead into the second half of the race. On the twelfth stage, Rodríguez achieved his second stage victory after out-lasting his rivals for the general classification on the steep climb to Mirador de Ézaro in Dumbría, putting another twelve seconds onto his lead over rider Alberto Contador. After the breakaway succeeded the following day, Rodríguez achieved another stage victory on the fourteenth stage to the Puerto de Ancares, where the longer climbs started to come into force in the race as part of three summit finishes in three consecutive stages. Similar to the move at the Mirador de Ézaro, Rodríguez accelerated away from his closest competitor, Contador, extending his race lead to 22 seconds. The following day, all attacks were negated, as the breakaway succeeded again; Antonio Piedra took the first victory for at a Vuelta a España, winning the stage by two minutes.
Rodríguez and Contador remained together for most of the race's queen stage, the first finish at the Cuitu Negru; on gradients approaching 25% in places, Rodríguez gapped Contador by two seconds, with a four-second time bonus ultimately leaving the gap at twenty-eight seconds post-stage and into the second and final rest day of the race. Following the rest day, Contador turned the advantage around with a surprise attack around midway through the stage. He left his rivals for the overall behind, and soloed to the stage victory. Rodríguez struggled during the stage, being dropped by another one of the race contenders, Alejandro Valverde (), and fell to third in the overall standings behind Contador and Valverde. Contador maintained the lead of the race until the end, eventually winning the race for a second time by 1' 16" over Valverde. Rodríguez was third, a further 21 seconds behind, with no other rider within ten minutes of Contador at the end of the race. Valverde took final-day victories in the points and combination sub-classifications, with Rodríguez losing the points competition in Madrid for the second year running after losing out to Bauke Mollema in 2011.
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 Combination classification Denotes the rider designated as the day's most combative s.t. A rider that 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 30 August 2012 — Vilagarcía de Arousa to Mirador de Ézaro,
The second half of the race commenced with a rolling stage starting in the Province of Pontevedra at Vilagarcía de Arousa, before it made its way into the Province of A Coruña and an ultimate summit finish at the Mirador de Ézaro. Despite not being the highest point of the stage, the Mirador de Ézaro provided a stern test for the remaining members of the peloton, as the average gradient of the long climb was over 13%, with certain sections of the climb reaching 20%, or higher. As a result of the short and steep climb, Joaquim Rodríguez, the race leader for , was considered as the main favourite for the stage – along with ninth stage winner Philippe Gilbert () – as he looked to restore some part of a race-leading margin nearly wiped out during the previous day's time trial. Mini-attacks set the course of the early running of the stage, with the field remaining as a whole for most of the first two hours of racing after several attacks were closed down within minutes.
It was not until the mark that an attack was allowed to gain substantial ground off the front of the main field. Four riders – Cameron Meyer of , 's Mikel Astarloza, rider Amaël Moinard and Kevin De Weert, representing the team – were allowed to freedom to create a lead of over seven minutes during the stage, but were gradually brought back and despite the chasing by the peloton, the lead quartet still held a lead of around half a minute at the bottom of the Mirador de Ézaro. Despite an attack by Astarloza's team-mate Igor Antón, were able to set Rodríguez up for his second stage victory of the race, with Alberto Contador () coming across the line eight seconds behind, having been the last rider to have been dropped by Rodríguez, to limit his deficit to thirteen seconds after time bonuses had been applied.
Stage 12 result RiderTeamTime 1 2 + 8" 3 + 13" 4 + 20" 5 + 23" 6 + 23" 7 + 27" 8 + 31" 9 + 33" 10 + 36"General classification after stage 12 RiderTeamTime 1 2 + 13" 3 + 51" 4 + 1' 20" 5 + 2' 59" 6 + 3' 29" 7 + 4' 22" 8 + 5' 17" 9 + 5' 18" 10 + 6' 01"
Stage 13 31 August 2012 — Santiago de Compostela to Ferrol,
Despite its parcours being lumpy and undulating, the thirteenth stage was categorised as a stage for one of the sprinters to achieve a victory on, and potentially their last chance of a stage win until the following week as up until the rest day, the following three stages would all have summit finishes. There were two intermediate sprint points during the stages, offering points to the points classification and bonus seconds towards the general classification, coming in A Laracha at , and in Catabois from the finish in Ferrol. Ferrol was hosting the race for the first time since 1993, when Djamolidine Abdoujaparov won the penultimate stage of that year's race. Much like the previous day's stage, mini-attacks set the course of the early running, with the field remaining as a whole for most of the first hour of racing after several attacks were closed down within minutes.
However, just after the mark, a group did form and was allowed to make a gap off the front of the field. Seven riders representing six teams – were the only squad to have two riders in the group – and achieved a lead of four minutes during the stage, with the peloton unwilling to let the advantage to anything larger. The gap was brought down at a quicker pace than normal, with and willing to bring it back for their sprinters John Degenkolb and Gianni Meersman respectively. However, the peloton never caught the breakaway during the stage, and after several moves with to go, 's Steve Cummings made a solo bid for victory with remaining, and remained clear until the end to take his first Grand Tour stage win, and his first victory for the team. 's Cameron Meyer bested Juan Antonio Flecha () for second place, four seconds behind Cummings, with the peloton led home by Degenkolb finished forty seconds behind Cummings.
Stage 13 result RiderTeamTime 1 2 + 4" 3 + 4" 4 + 14" 5 + 14" 6 + 14" 7 + 40" 8 + 40" 9 + 40" 10 + 40"General classification after stage 13 RiderTeamTime 1 2 + 13" 3 + 51" 4 + 1' 20" 5 + 2' 59" 6 + 3' 29" 7 + 4' 22" 8 + 5' 17" 9 + 5' 18" 10 + 6' 01"
Stage 14 1 September 2012 — Palas de Rei to Puerto de Ancares,
The race returned to the mountains for the first of three consecutive summit finishes, that were expected to alter the general classification standings. Instead of the short, punchy climbs that had featured in the race prior to the fourteenth stage, longer climbs were included in the stage's itinerary. There were five categorised climbs, with the steeper climbs coming towards the end of the stage; inside the final of the stage were two first-category ascents of the Alto Folgueiras de Aigas – averaging 6.7% for its length – and the final climb of the Puerto de Ancares which averaged 8.1%, but reaching almost 13% in places, en route to the summit at above sea level. The climb also contained a downhill section of around a kilometre in length, just after halfway up the climb.
A four-rider move initially got clear in the opening kilometres of the stage, but they were brought back before of the parcours had been completed. After that, a larger group consisting of sixteen riders, including the four-time defending mountains classification winner David Moncoutié () and fourth stage winner Simon Clarke of advanced forward. With members of their respective teams in the breakaway as well, Joaquim Rodríguez's squad and the of Alejandro Valverde, sat back in the peloton and allowed and to control the pace for their respective protected riders Alberto Contador and Chris Froome. The leaders held a lead of over three minutes at one point, with the break splitting apart on the Alto Folgueiras de Aigas, and on the descent, Alberto Losada – Rodríguez's team-mate in the break – ventured off the front on his own. The peloton had reduced the gap to two minutes by this point, and were continuing to close the gap gradually as they reached the bottom of the final climb of the stage.
maintained station at the front of the peloton, with Contador being paced by three of his team-mates, and his rivals Rodríguez and Valverde were in close order to him. With the pace being accelerated, the peloton was being reduced in numbers, with only the race contenders remaining after a time. Froome cracked on the climb at one point, but managed to recover sufficiently to rejoin the leaders' group – having caught and passed Losada – before eventually falling off the back again, eventually losing 50 seconds, falling to 1' 41 behind, after time bonuses were applied. Contador launched an attack with to go, and nobody followed immediately; however, Rodríguez eventually set off in pursuit of Contador, catching him with around a kilometre remaining. Contador made one last bid for victory, but Rodríguez had enough to combat the move, and eventually accelerated away from him and won his third stage of the race, gapping Contador by five seconds, and added nine seconds to his overall lead.
Stage 14 result RiderTeamTime 1 2 + 5" 3 + 13" 4 + 35" 5 + 38" 6 + 44" 7 + 56" 8 + 1' 04" 9 + 1' 13" 10 + 1' 17"General classification after stage 14 RiderTeamTime 1 2 + 22" 3 + 1' 41" 4 + 1' 41" 5 + 4' 16" 6 + 5' 07" 7 + 5' 51" 8 + 6' 13" 9 + 6' 34" 10 + 7' 16"
Stage 15 2 September 2012 — La Robla to Lagos de Covadonga,
For the second of the three consecutive summit finishes, the riders had to negotiate two categorised climbs – as well as the unclassified Puerto de Pajares – before the final climb, categorised as a climb of "Categoria Especial", to Lagos de Covadonga. Although the final climb was less steep in gradient compared to the climb before it, the Alto del Mirador del Fito – 7% compared to the latter's 8.3% – it reached 15% in places. As well as that, there were two sections of downhill – each of around in length – in the final of the climb, before ramping up again for the finish. In the early kilometres of the stage, a group of nineteen riders formed the early hallmarks of a breakaway group, before it was eventually established with ten riders in the group, as the peloton negotiated the windy conditions of the stage.