I unicycled up Mt. Diablo (18km / 11mi) (5.5% gradient) on my 29er with 150mm cranks today. Time: 1:25
Last weekend, I biked up with my bike with 125mm cranks, and a 1:1 lowest gear ratio. Time: 1:35
Hopefully I can do a bike ride with 150mm cranks to get a more equal comparison. I changed to 150mm cranks since I totally blew up in the last half of my bike ride, as my cadence dropped to 60rpm.
It was super windy today, but I still cut a bunch of time. I have a feeling a crank length in between 150mm and 125mm would be best for me on a less windy day. It would be interesting to test this on more climbs, but it seems like my ‘torque effectiveness’
Here are links of the cropped rides. (I don’t know if this will be available after the 30 month trial)
PS:
My time is getting worse each year even though I am analyzing it more. Probably need to train more 
1:14 (2 years ago)
1:16 (1 year ago)
1:25 (this year)
Curious why you’re using 125 and 150mm cranks on your bike.
There’s not a climb locally that I couldn’t smoke my unicycle with my bike.
I was using 125mm on my bike to train for unicycling since the last two years I rode Mt. Diablo with 125mm, and I found riding down hills after training on my unicycle was more boring/tiring compared to biking.
I bike and unicycle approximately equal amounts, and on a shorter 2.7km 9% climb, out of a few dozen climbs, my bike PR is about 6% faster.
Up Mt. Diablo, my unicycle PR is is about 2% faster than my bike PR, which seems negligible.
I would say biking uphill is more efficient for me, but not by much. Other factors (fitness, correct gearing) seem more important.
For efficiency, I would recommend trying shorter cranks on the 29er (and longer ones on the bike). My only rides up Mt. Diablo were on 36" wheels with 150mm cranks, but think you would be fine with 140s or even 125s.
Actually I did climb Diablo once on a 29" with 140s. They seemed to work fine on the way up, but about killed me on the way down with no brakes! 
140mm does sound good.
I had brakes going down, and I still had a painful time desending. Even with 125mm or any other lengths, going down a ~6% paved road for an hour is not fun for me. 
hmm… the descent does sound a little boring:
a) is there not a more fun way down, say a downhill trail?
b) is your brake not too weak if it’s painful? Although I could see it being a little tedious and would rather ride down a trail, on either my 29 or 36 with 127s or 150s it doesn’t seem like that would be a problem - just ride the brake smoothly (OK, I upgraded my 36er to a 200mm disc and Shimano Z brake to have more power but that was for riding steep downhill).
I also am very sure that I am significantly faster on the bike on any climb, although on the right gradient I often pass bikes but only because the riders are simply less fit. While lighter, the unicycle simple requires more energy to maintain balance (whereas on the bike virtually all energy and effort goes into propelling you forward). Plus the gears allow you to fine-tune your available power.
