Russia\'s Sergey Kirdyapkin won gold in the men\'s 50km race walk at the London Games on Saturday in an Olympic record time of three hours 35 minutes 59 seconds.  The 32-year-old double world champion shaved more than a second off Alex Schwazer\'s record of 3:37:09 to finish 54 seconds ahead of Australia\'s Jared Tallent, whose time was also inside the previous Olympic record and a personal best.  China\'s Si Tianfeng, 28, won bronze in a personal best of 3:37:16, adding to Chen Ding\'s 20km gold and Wang Zhen\'s bronze a week ago - China\'s first men\'s race walk medals, the BBC reported.  The Russian trio of Kirdyapkin, Igor Erokhin and last year\'s world champion Sergey Bakulin were strong medal favourites after Italy\'s defending champion Schwazer was excluded from the London Games on Monday for testing positive for EPO.  \"I gave it all I could in the last 10km, I came home as hard as I could but I just couldn\'t catch Kirdyapkin, he\'s a true champion. He\'s won two world championships, one world cup and now the Olympic gold medal,\" the 27-year-old said.  Before Saturday\'s race Kirdyapkin had already set this year\'s leading time (3:38:08) when he won the 2012 World Race Walking Cup in May.