Bukit Timah, 39 km. Front derailleur is not shifting smoothly despite a new shifter cable. Worn chain rings perhaps? Or just poor adjustment? It makes no sense that the derailleur is over the biggest chainring but the chain remains on the middle chainring (which is what happened when the cable frayed on my 2014 expedition, but I've had the cable replaced). I turn the high adjustment screw, then the barrel adjuster this way and that. Until, finally, things click into place.
On the one hand, it's just fiddling. On the other hand, there are some fundamental principles involved.