I've long been
a fan of the Lightning crank, as it was the only light crank that will work with the Quarq powermeter.
I've
corresponded at
times with Tim Brummer, the principal with Lightning, and the holder of the crank
patent.
When I started
researching tandem cranks a couple of months ago, I came to the awful realization that our choices were crummy. I emailed Tim Brummer informing him of the dearth of tandem cranksets, and pointed out that since the Lightning already has a triple, it isn't such a large step to make a tandem crankset as well. He's expressed growing interest to me, and I am glad to see that this is getting around.
The Lightning crank has been much discussed on the Weight Weenie forum. A lot of information on these multi-page threads:
Lightning Cranks: now April
Lightning Crank photos
Madcow at Fairwheel bicycles is famous for his reviews of weight weenie components. His
crankset review included the Lightning crank, and is generally favorable.
A Lightning crank could offer significant tandem weight savings. The most modern outboard bearing tandem crankset now is the 1820 gram
FSA SLK Carbon Mego Exo. A Lightning tandem crankset with a titanium spindle would weigh 1300 grams, a savings of 520 grams, or 1.15 lbs. For someone who already had a crankset, this upgrade would cost $3/gram.
For a new build considering cranks, the Lightning would be well within reason on a gram per dollar basis:
FSA SLK Carbon Mego Exo...........1820 gm................
$760
Lightning Carbon Tandem..............1300 gm...............$1500
Difference...................................520 gm..............$740
Price per gram......................... ($740/520 gm =)........$1.4 /gm
As to whether the Lightning crank is sufficiently robust to handle tandem loads, the Madcow review had pretty good stiffness, there is already a heavy duty version, and replacing the aluminum spindle with titanium should further upgrade its capacity, and Brummer can make other modifications to the crank if needed (e.g. stronger spyder).