To answer some of the previous questions I moved here 6 months ago and have been riding quite a bit. Sundays are fine all around Manila, but other days can be a bit harrowing. There is a great ride from Alabong to Taguytuy that hundreds of people do every weekend. I have seen many clubs, racing teams, and individuals like myself. Getting out of Manila sucks, but then the roads are not bad.
Within the best bet is to get into some of the large neighborhood complexes. I have found a good 6k loop through Dasmarians and Forbestown in Makati/Global City area. A lot of people do the rides around High Street in G-City and Mall of Asia in Pasya...boring...but doable.