SINGAPORE — Three days a week, a group of 15 men in their 20s and 30s — consisting of a nurse, chef, property agent, army regular, small business owner, air steward and IT support engineer, among others — would look forward to the evenings when they would make their way from all over the island to the Somerset Skate Park on Wednesdays, or the Xtreme Skate Park at East Coast Park on Tuesdays and Sundays.