<Credits: Tom Webster>
I'm concerned by these 15km/h limit signs that have been going up recently. I thought the proposal was to limit to 15km/h on footpaths and 25km/h on cycletracks but as you can see this 15km/h is on pcn cycletrack which is far too restrictive, I sometimes RUN through this area faster than that!
I don't think any cycling speed limits are a good idea. They are as much a green light to travelling inappropiatly near the limit (e.g. round a tight blind bend) as they are a red light to cycling inappropriately fast elsewhere. Unlike driving on the roads at 50kph+ where limits are sensible because sight lines, reaction times, and braking distances are reasonably consistant and often dictate the appropiate speed: safe speed for cycling off road is more about what is appropiate for the particular layout and situation.
Limiting to 25km/h is basically sending the message don't bother trying to cycle as a sport or serious commute in Singapore and 15kph is making cycling even less attractive. Surely it is better to send a message of encouraging cycles to give way to pedestrians, share the space, and have safe cycling behaviour and rather than putting the focus of attention on clandestine limits.
FYI in UK speed limits do not apply to bicycles on or off the road, except the special case of royal parks where speed limits do apply to bicycles.