Maybe The Circle in Quezon City is still alive and kickin' for cyclists. If you don't mind going around in circles in a 1 km circumference. I used to go there with my cycling buddies way back then when I was 11 until I left for the U.S. at 14. I didn't get a chance to check it out when I went home for the first time in 2000 and again in 2007. Basically people go there to race. I wouldn't recommend biking around the city with that kind of traffic.