Crank length on trikes?
 

On my DF bike, I normally use 175mm cranks. I notice my trike has 165mm ones. Is there a reason for those munchkin crank arms, or should I swap my trike to the 175mm cranks?

Bents do better with high cadences than with low cadences, at least on hills. Shorter cranks facilitate higher cadences, they are easier to spin. Stick with the 165mm. Your knees will appreciate it. Your area is not so hilly as mine is, but trikes are significantly heavier than DF bikes, except for a few downhill types and high cadences are to be recommended especially in climbing. Since the trike is so different in other respects, doubt you will notice the 10mm difference in length otherwise.
Steve

I know nothing about trikes, but I recently switched from 175's to 152's on my LWB bent. I geared it down a bit with smaller chain rings to make up for the slight loss of leverage on the pedals. I was getting a little knee pain on the left knee and the left knee was weaker than the right because of a previous stroke.
In short, I love them. I just finished a century last weekend with a 75 miler the next day. The slight bit of knee pain I had completely left me, and faster cadence more than makes up for the slight loss of leverage. They may not be for everyone, but for me they are perfect.

Hi Steve!

So do DF bikes, from what I read. Being a tall person with large feet, I've never been able to maintain high cadence nor do I find it comfortable. Since there are no hills here, does the "high cadence" thing really matter?

Crank length regarding strain on knees or other body parts is an ambiguous thing. Although a shorter crank will give you a shorter "throw" distance, it also effectively raises the gear ratio. A longer crank increases the throw distance, but reduces the amount of force you have to apply to the pedals at any given gear setting or speed. In other words, when your feet travel through a longer arc to produce a certain distance of wheel travel, this is the equivalent of lowering the gear. People with longer legs might find that longer cranks allow them to use their leg length to better advantage, but everyone is different in what works best for them.

I have long legs and prefer a 190mm crank. My ability to handle a longer throw distance lets me perform at my best with this crank length. When I've used a quadraped tricycle, I gradually evolved my hand crank length to 255mm, using adjustable cranks I built myself. I'm also a Kayak paddler and use this
255mm hand crank length on a stationary hand-cranking exercise machine, that gives me some good indoor training for paddling strength. I recommend quadraped tricycles for anyone who wants to build strength and endurance for Kayak and Canoe paddling.