Captain's Crankarm length
 

Is there any reason that the length of my crank arms, as captain of a tandem, should be longer than the crank arms I'm comfortable with on my single bikes? I can't imagine there would be. But a local dealer for one of the leading tandem builders tells me that all tandems the builder makes come with 175mm crank arms for the captain, regardless of the size of the tandem. That sounds crazy. What am I missing?

I like a 175mm crank arm length on all of my bikes, but I'm also 6'2" tall with a 35" inseam. I would think that shorter riders wouldn't like that kind of length regardless of what kind of a bike it may be.

You certainly shouldn't use a length that you are not comfortable with.
Two reasons for the captains to be longer than the stoker is that they are often taller and also a more experienced cyclist.
Being more experienced they often prefer a higher cadence than the stoker. The extra length in the crank helps to slow them down and reduce the cadence discrepancy.

That is, in fact, crazy. Both riders should have crank lengths that are comfortable for their physiology. A proper bike fit is critical for a comfortable ride. If the riders find that their cadences don't line up, then it's okay to experiment with different crank lengths, but I'd always recommend shorter cranks to avoid injury.
Our tandem has 172.5mm cranks in the front and 165mm cranks in the rear... because that's what we use on all our single bikes.

We were able to specify both front and rear crank arm lengths at no extra charge on our da Vinci Joint Venture. They have nine crank lengths from 150mm to 200mm and with 2.5mm increments from 165-175mm. Additionally there are two different sets of lengths for their adult/child triple-hole cranks. Choices are good to have! You can purchase their cranks without buying a bike.

The extra length is not intended to "slow the Captain down". They are already used to whatever cadence they adopt. The shorter length on the Stoker crank otoh may help them keep up.

At 6'2" it is very possible that you could, in fact, use even longer cranks! But that would require extensive re-design of your entire bicycle. The current craze for extremely short cranks flies in the face of everything that is known about bio-mechanical efficiency.

Yeah, I agree! I've never tried anything longer, but I've always been quite content with the 175mm cranks. I was actually taller than 6'2" at one time, too, but that's another geezer back story for another time.......LOL. My leg length has remained the same, though.

Yeah, that's crazy, but that's how it is. On our tandem, both our crank lengths now = 5.5 X inseam in inches. Mine is 31", so 175s work. Stoker's is 27", so we finally got 151mm custom cranks for her. She used to use the stock 170s, which were actually fine, but she likes the shorter ones better. Though I have the feeling that she has less power on the steep stuff, she can spin faster on the flats and easy climbs.

What short crank trend? The trend I notice is longer cranks on single bikes. I don't like it. I prefer short cranks.