Just got back from a couple of days of hard technical riding in Vancouver and Squamish. The first day was on my KH24 with 137’s and a brake. The 2nd day was on a borrowed KH24 with 165’s and no brake, so I had a good chance to compare the two. It was actually the first time in 2 years that I’ve ridden a 24" with longer than 150’s.
My impression is that there are some good reasons to use shorter cranks for all-around riding, mainly to do with smoothness. But specifically for technical downhill on rough, irregular terrain- I don’t think it’s easier. For me, I felt about the same in terms of comfort until I reach the limit of my ability to use the brake to replace the loss of torque with shorter cranks.
As terrain gets steeper, it felt like it took more and more concentration to have the same level of instant braking control with a brake, that you get with your feet. Beyond some steepness threshold, when I started to have to really work my way down a slope with drops to steep terrain and I wanted to instantly stop and where a fall might be uncomfortable, it felt really good to have the control of longer cranks.
It feels like it’s a good goal to try to get better at the brake until it can really replace foot-braking in all situations with shorter cranks, but for sure it is a learned skill.
Kris