Ron Clark and his 2739 on cinders was indeed a phenomenal result but even he had his limits and being a diesel guy rather than speed merchant he would’ve had his limit racing against people like Bekele, Kipchoge, Farah and even Rupp. Would Clark have beaten 27 minutes in today’s era? I think not. Rupp has 26:44 and taking Clark to today’s era I think he would’ve been stuck at around 2710 to 2715. Running on dirt it was not that much of a disadvantage that people think and remember Bedford only ran about 10 seconds slower when he ran at Portsmouth on dirt for 10,000 m on a very hot day.