Which is faster running or cycling. And what i meant by faster.
Faster burning your fats. And slim down
I think running can fit more easily and easier to our typical SG schedules of work + family commitments, or even no family you might have GF, so can fit in easier.
Unless if your GF also into cycling, then yeah....cycling might make more sense.
I listed most points below, point 4 is more on physiological and training aspects. Points 1-3 more like lifestyle effects.
1. Cycling might be more enjoyable to some, more "inputs" and more engaging/stimulating, but there are nuances to this coz PCN and road are different. MB is yet another thing, more adrenaline and skills based than anything.
1a. Cycling might be more dangerous in most cases. If you do not drive regularly, best not to cycle also, at most just do PCN and places like Sentosa, MBS can liao. But PCN can get boring after 1 year. That means other than being able to ride confidently and handle the bike in road or walking path situations, ie interacting with other road or path users, the "driving experience", you also need to really know how to "drive" on the road like any other driver, just in a cycling sense with cycling experience thrown in. There are other nuances as well, like how 99% of drivers dont like cyclists so you need to pick up such experience as such.
So, the learning curve is higher in terms of skills and technicalities that is not tied to fitness/aerobic. Running is tied a lot more to fitness/aerobic and biomechanics.
1b. Running is definitely more injury prone, more things to go wrong biomechanically that would cause you issue, esp to the average runner. Cycling less prone, but then has less benefits due to less impact loading and no eccentric loading. But no a biig issue if you strength train, which you SHOULD.
2. Cycling is "cooler" and more enjoyable in this aspect, if you are especially affected by the heat. Easier to bring along water / ice water to splash, definitely more enjoyable. Esp if you have access along the way to a working water cooler, eg Esplanade toilet or Sentosa, esp the Sentosa one which is ICE COLD. For Sentosa, what sweating if you are really into splashing your top with ice water regularly, no such thing as sweating.

Your body can literally spend everything on the aerobic / anaerobic / surge aspects......and not on cooling.
3. Running is overall more time efficient, so in a way more efficient overall. There is a lot of faffing around for cycling, be it washing bike or charging devices. Travelling to the usual training venue can serve as warm up tho...... Not say very significant but it is definitely there.
4. I find running to be more taxed by aerobic system (or even anaerboic system).....you know, cardio.
Cycling is more biased towards muscular based, ie your muscles give up faster / earlier. Unless if you gym rat experience already. I know of cycling pals who have gym background (just look at their legs) no need to be bodybuilder type but just someone who lifts and squats etc , at first is newbie but in just like what......2-3 months, neuromuscularly they pick up very fast ie the brain wires extra motor pathway to bring cycling efficiency up......then can see their surges at Sentosa improves so fast.
4a. Depends on your built also, and genetic makeup. For me i picked up so much faster via running, but then part of the reason is probably also coz of my racewalking background that i did since covid p2
. For cycling, the progress has been slower, for one reason or another. And i actually went in with more and better training knowledge for cycling, coz i have already been running for 1 years prior.
I suspect part of it is coz cycling is also more muscularly biased, and also if you are doing this in group cycling a good part of it is surges (i dont fare well in short term surges). Could be a neuromuscular thingy also.
Generally, if you are in your 20s or even 30s, no issue lah. For me i am in my 50s, so........
But more steady state stuff, even for say short 5km on WCH or 5km times 2 on TMCR straight no-traffic lights stretch, i am ok. I go Sentosa rolling terrain, i quite terok one, even though i have crazy amount of experience there already, be it group cycling there in the fastest pace group or normal daily grind there vs other cyclists. (still, via my own pacing and power outputs, i dont lose out much to even fast cyclists there and the local racing groups.....but i must pace on my own and not follow their surgey riding).
But, since Sentosa is basically just 2km from my place, i bo bian, also it is much safer to train there.
MBS and BEG areas quite dangerous, and now is inconvenient due to them building the link bridge bt GBTB and Founders MRT beside the MB bridge. But MBS, MB, BEG area is best in terms of scenery and human scenery, if you know what i mean.
4b. Long story cut short, LT2 cycling sessions, you'd find your legs get sore / lactate H+ ions build up before your LT2 running, your HR for cycling is also a fair bit lower (based on lactate measurements on the meter) than your HR for running (also based on blood lactate measurements).
ie LT2 blood lactate measurements on the meter of 3-4 mmol/L, running HR could be 160+, but for cycling 145-150bpm.
Correspondingly and needless to say, more oxygen used for running. This is also true for easy zone 2 paces for both cycling and running, but i shall not go into details for that.
Generally there is more energy used just to support and stabilize your body while running as it is totally weight bearing on your legs, hence the higher HR overall - this is one of the main factors also.