It’s easy to imagine that the stiffer cranks feel better, or have better “power transfer,” which is a particularly vague and ill-defined concept. From this, we can generalize and say that the most flexible crank is about 50% more flexible than the stiffest crank. This is the question: is a stiffer drivetrain actually more efficient, or does it just feel that way? Looking at the numbers, we can see that average deflections range from roughly 0.20 inches to 0.30 inches. But it’s far from clear whether that tactile, from-my-quads-directly-to-the-road sensation is actually faster. As desirable as those traits are, and even after a crank’s stiffness is proven empirically, the outcome still seems subjective-we are simply going by how many people feel more efficient on a bike with a stiff drivetrain. Stiffness implies efficiency, along with the notion of a stiffer bike inspiring confident and responsive handling. Notes about stiffness: According to conventional wisdom, the more pedaling stiffness the better. Stiffness/Weight: Is determined by: (1/average deflection)/weight)x10000 The loading has also been moved slightly inward toward the crank arm. With the new fixture, we’ve switched to using actual steel pedal spindles removed from a set of production pedals. Further more in previous tests a large solid rod was used to simulate the pedal and load was applied 60mm from crank arm. This method uses a total load of 200 pounds, in comparison to the old test which used a total load of 250 pounds. These will be labeled as Deflection-D(Drive side deflection) and Deflection-ND(non-drive side deflection). A lower number represents a stiffer crank. Each arm was tested three times and an average of those measurements is the result. Another 150 lbs was added and the difference was measured in mm. Luckily, Jason Krantz is back as our resident data-cruncher (Jason is an experienced mechanical engineer with a strong background in both finite element analysis and composite materials.) We’re always happy to have him work with us on our tests and place a high value on his contributions.ĭisclaimer: A lot of typing and numbers have gone into this article and we apologize in advance for any typos, but would warn that the possibility of mistakes is present.Ībout the testing method: Each arm was preloaded with 50 lbs of weight, then all calipers and load cells were zeroed out. Being that only 2 of the first 12 cranks tested in the last round carry over from previous tests we felt this was a good time to make the change. Please note that because of the new fixture and testing loads, results from this and future tests are not comparable to results from previous tests. Because of this and a desire to build a new testing fixture, particularly one that would handle BB30 cranks as well, we decided it was time to retire the old tests and start again with a clean slate. One thing we’ve come to realize is that while some cranks have obvious changes over the years, others have quietly evolved behind the scenes. As a lot of you tuning in already know, we’ve been working on our in-house road crank tests for the last 7 years, with our updates posted alongside all the previously tested cranks.