Cost: $800 for reviewed model
Models: Road, tandem, mountain; aluminum or carbon “spyders,” 94, 110 and 130 bolt circle diameters; compact, double or triple chainrings; regular or ceramic bearings; all bottom bracket sizes; prices range from $650 to $1,680
Crankarm Lengths: 160, 162.5, 165, 167.5, 170, 172.5, 175, 177.5, 180, 182.5, 185 and 190mm
Q Factor: (width between crankarms from pedal seat to pedal seat) 150mm
Weight: crankarms and spider: 365 grams; bottom bracket cups: 70 grams; total: 435
How obtained: sample from company
RBR advertiser: no
Miles tested: 400
Custom Carbon Crankset In Your Size
Last week, I explained that during a recent professional bicycle fitting I discovered that I should switch from the 175mm crankarms I’ve been riding for the last 30 years to shorter crankarms. I have since switched to 170mm arms on my road bikes and took
my fitter’s advice and gone to 160mm crankarms on my time trial bike. Super-short crankarms make sense on a TT bike for some riders because they help keep the knees from striking your ribcage when you’re riding in the aero position.
I’ve been impressed with how the shorter arms have felt more efficient and have allowed me to ride more comfortably. Something else I like is how it feels like the pedals come around more quickly. I notice this most when standing to climb. It seems like
each complete pedal stroke takes less time and that I get to apply power sooner with each leg. You might think with less recovery time per stroke, the more-rapid turnover would be a negative, but it feels like it adds power for me and I like it a lot.
Lightning Cycle Dynamics to the rescue
As much as I enjoy the feeling of the shorter crankarms, I had a hard time finding a quality 160mm-crankarm crankset. Campagnolo, Shimano and SRAM don’t offer them. And you can find a few budget aluminum models online, but I needed something that wouldn’t
flex or wear out right away.
Finally, I remembered that Lightning Cycle Dynamics, a super-innovative recumbent bicycle manufacturer located in Lompoc, California, offers a trick carbon crankset in almost every length. I tested a couple of their super-fast and fun recumbents as Bicycling magazine’s tech editor years ago. So I called company owner Tim Brummer to learn whether his crankset would fit my needs and my Cervelo P2 time trial bike. I was excited when he told me it would be the perfect crank and that he could
send me a 160mm model ASAP.
Zinn Cycles offers even more lengths
As far as I have been able to determine, apart from the budget 160mm cranksets available online, the only other brand offering reasonably readily available custom-length crankarms is Zinn Cycles.
According to their website, theirs are available in a whopping size range of from 130 to 220mm lengths, and in three models, too. Owner Lennard Zinn is a frame-builder and Velo magazine’s tech guru and has written a lot about
the benefits of getting the correct size crankarms. So, I’m confident that would be a good crankset source. too.
What I like most about the Lightning crankset is that it’s a splined-spindle design. By that I mean that both crankarms have about half of the hard-anodized 7075 T6-aluminum bottom bracket spindle built into them. The inside ends of the spindle are splined.
So installation is as easy as installing the beautifully machined bottom bracket cups into the frame, pushing the crankarms/spindles into the cups and inserting the 6Al/4V-titanium spindle center bolt and tightening it to draw the spindle halves together
and make the crankset one piece.
Interestingly, this splined (the technical term is “Hirth joint“) spindle is almost identical to how Campagnolo’s Ultra Torque cranksets work, yet Lightning patented theirs first and has licensed
its use to Specialized, which has used it in some of their cranksets.
The benefits of Lightning’s design are easy installation, a super-clean look, weight savings and maximum pedaling efficiency. I have to admit, though, that I worried I’d be able to feel some lag or reduction in pedaling power and that I might loosen the
But several weeks of hard rides, including intervals on rolling courses and jamming up longer hills trying to win the king of the hill against my teammates has proved that these cutting-edge cranks are awesomely stiff and that the splined spindle and
bolt will not loosen under anything I’ve been able to do to them.
I’m equally impressed with the bearings, which felt so smooth during installation I was expecting them to possibly develop play. Any looseness can easily be removed in seconds with the adjusting ring that tightens against the non-drive bottom bracket
cup. But no adjustment has been needed yet and the crankset spins effortlessly.
A special feature on my crankset is the aero carbon “spyder,” which I requested since the crank is on my time trial bike and every streamlining feature is helpful. This “spyder” is 15 grams lighter than Lightning’s aluminum models too. And, the crankarms
themselves are oval to cut more drag.
Overall, the Lightning Carbon is a great way to step up to the right-length crankarms while significantly upgrading your crankset, drivetrain and pedal power.
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 8,000. Click to read Jim’s full bio.