I think are benefits to be gained by working on climbing (beyond just improved overall fitness). The steeper the climbs, I think the more it matters. I donāt think itās just a cadence/gearing thing.
I hear some people say āwatts are wattsā, but there is definitely a difference in biomechanics when climbing an 8% grade vs riding on the flats at the same power and cadence. Some call it momentum or inertia and you often hear it discussed in the context of a trainer having a big heavy flywheel (more like riding the flats) vs. a smaller flywheel (more like climbing).
Riding in the flats, I always feel like Iām āon top of the gearā and my cadence feels smooth and efficient even spinning well over 90 rpm. Contrast that with a 10% climb and my cadence feels frantic at 90 rpm and much harder for me to maintain power for an extended period. I feel like on steep hills, you really need to apply force more constantly throughout the pedal stroke because you have the constant resistance of gravity to fight with. On the flats, Iām guessing that there are bigger ādead spotsā in my pedal stroke, but the big power quadrants more than make up for it for overall wattage.
I hear about people struggling to hold power on a downhill or tailwind section and thatās where I excel. Holding it on a steep hill, much harder for me. Cadence certainly plays into that, but I think itās the different biomechanics of climbing that actually results in the lower cadence.
I also think this is somewhat trainable. Iāve always been able to do my best power on the flats, probably because I love training/riding this way with long SS and Z4 work on the flats. The climbs around here are short and I tend to avoid them, so I just donāt think my legs are as efficient when they have to fight the entire pedal stroke. Iāve worked on climbing quite a bit this year and forced myself to do a lot of steep climbing and Iāve seen some improvement in my climbing endurance and efficiency.
I donāt think climb-specific training is going to make a huge difference compared to just boosting your fitness, but I do think you need good mechanics and efficiency to get the best possible climbing performance out of whatever fitness you have.
Iāve got zero science to back any of this up, just personal observation.