Different Cassette?

[OakLeaf]

I thought I was going to fall over.

The thing is, that it's nearly impossible to pedal both smoothly and with a ton of force, especially at a very low cadence. Even many pro riders on TV sway from side to side when they're climbing or sprinting. Touch wood, but so far I've never felt like I was going to fall over on a triple, and I've seen 3 mph plenty of times. I definitely felt like I was going to fall over when I demo'ed a bike with a compact at the retreat when I returned to road riding - and I definitely felt like I was going to fall over the following summer when I took my old race bike (low gear 42x21) up a serious hill around here. (Both times I unclipped and walked before I fell over involuntarily. ) So I think falling over has as much to do with pedaling smoothness as it does with speed. That is, the wheels are producing a certain amount of gyroscopic force, which is fixed for any given speed and wheel; but the rider input is moving the bike side to side by a greater or lesser degree, working against those gyroscopic forces, depending on how smoothly they're pedaling. And that's where shorter gears can help.

If I understand it correctly, MTB wheels are producing a greater amount of gyroscopic force just because the rims and tires are heavier (or technically, they have greater mass)? If that's the case, that would explain the ability to go slower without falling over than one could on a road bike?

(And just for the record, I doubt one could ever walk faster than pedal. Sure we can all easily walk 4 mph on the flats, but up those hills that we're struggling to ride? I don't think so.)

For myself (meaning my present strength level, my terrain, and my lack of commitment to get much stronger in the near future), I'm only talking about putting a 12-27 in place of my current 12-25, or putting a 26T chainring in place of my current 30. Probably the former and almost certainly not both. With my 39T middle ring (which I like and don't want to change), going down to 26 in front would be a pretty big jump.