Originally Posted by
cyclezen
There is this 'Magic' in cycling which seems to happen (both good and Bad magic) which is : when you're climbing and generally going quite slow, at slow cadence (under 60 rpm), going into a smaller/easier gear doesn't make it 'easier'
Yes it does, or at least, it does in my experience. Gearing bottom-out puts a lower bound on the amount of force you need to pedal at in order to keep going; lower gears decrease this bound. Plenty of the hills around me force me to go at least somewhat hard if I'm on a bike with typical road gearing, but if I'm on my gravel bike (which has a 19" bottom gear), I have the option to take it easy if I want to.
you just go even slower...
You only go slower if you use the lower gears to go easier. For the most part, in my experience, gearing bottom-out is bad for power: the lower your cadence has been kicked, the more dramatic this is. Although it's sometimes easier to produce more pedaling force at lower cadences, there are harsh limits to this. If I'm fighting to keep the pedals turning over at 50rpm, changing to a higher gear that sends me down to 40rpm is unlikely to facilitate the corresponding 5/4ths increase in pedaling force that would allow me to maintain the same power.
My '83 Miyata has a 42-28 low gear, while my Emonda has a 34-28. On moderate climbs, the Emonda has a speed advantage of a couple percent, which is in agreement with basic kinematic differences between the bikes (i.e. the Emonda's 5-pound weight advantage). But on climbs where I start feeling bottomed out even on the Emonda, its advantage over the Miyata can quickly rise to over 10%.