Is the Compact Crankset a Concrete Aid? Let's Talk About It

Sub-title: We've observed that even at high levels and in the most demanding races, many cyclists still choose the compact crankset. In the amateur cycling world, it has been a blessing for less experienced riders, as it allows them to "save themselves" even on challenging courses. But what are the real advantages? Let's discover them together...

Twenty years after its appearance, we can confidently say that the compact crankset has revolutionized cycling. During the 2003 Tour de France, FSA, thanks to an idea suggested by Fausto Pinarello, produced the first "compact" crankset, which was used by American rider Tyler Hamilton at the time, a member of Team CSC, who competed in and completed that Tour with a clavicle microfracture sustained at the beginning of the French race. Claudio Marra, Vice President and Global Marketing Manager of FSA, in agreement with Bjarne Riis, team manager of Team CSC, decided to use a carbon crankset with 52-36 teeth for the first time. Until then, professional cyclists were accustomed to using a 53-39 and frowned upon chainrings with lower teeth counts, relegating them to purely amateur use. However, this epochal choice was made to facilitate the pedaling of the injured American rider. So much so that Hamilton immediately benefited from it, even winning the sixteenth stage.

What has happened since then is well-known history. We have witnessed a complete change in climbing techniques and pedaling. Over the years, agility has assumed an increasingly important role, precisely because it has been observed that, with the same power output, using more agile gear ratios results in a significant reduction in muscular fatigue.

Starting from this point, we decided to quantify how much advantage a more agile gear ratio can provide. Today's high cadences are made possible in part by the use of rear cassettes with more than 30 teeth (now widespread among professionals with the use of a 54-40 chainring). Even manufacturing companies have radically changed the design of new cranksets dedicated to professionals.

Considering the increase in rear gear options and the increase in riding speeds, the classic 53-39 has gradually been phased out, as it is now considered too "heavy" for professionals, albeit difficult for average amateurs to digest. Hence, our test: how much does a moderately trained cyclist save with a 36-tooth chainring? To understand this, we conducted a road test: 52-36 vs. the classic 53-39, using a 25-tooth rear gear for both. We selected a 750-meter uphill section with a consistent 7% gradient and pedaled at a constant speed of 15 km/h. We tackled this section six times, using the 36-25 for the first three attempts and the classic 39-25 for the remaining ones. After recording the values, we averaged the results of the three attempts and compared the two averages to determine the difference between the two options.

CONCLUSIONS: We aimed for a type of effort that would ensure the most precise success of the tests. At the end of the test, as expected, the 36-25 showed a small advantage, albeit smaller than we expected in terms of power output. The difference between the two averages is only 5 watts, a nearly negligible difference, but when analyzed in relation to the average cadence of the test, it tells us much more. The cadence between the two options changes drastically since the RPM difference, with the same rear gear ratio, is a significant 12 RPM, a data point that should not be overlooked. In terms of perception, we would have expected, given the greater effort required to turn the 39-25, a more noticeable difference in terms of watts. It should be clarified that going from 39 to 36 is the first step toward a compact (hence the term "mid-compact" for the 52/36 combination). When paired with a 25-tooth rear gear, it has only a 258mm difference in metric development, corresponding to 8.3%. In terms of watts, the difference we measured corresponds to a savings of about 2%, putting us in front of two considerations. The first, almost in contrast to what we have demonstrated, is that when tackling a steep climb, a larger chainring is more advantageous since the ratio of distance traveled to the effort is more favorable. In the long run, the opposite holds true. When facing many climbs, the reduced leg effort (2%) repeated over time leads to a significant advantage, especially in the context of a Gran Fondo. This gain would be much more tangible using a 34-tooth chainring (that of "real" compacts), which offers a metric development that is 430mm shorter (considering the 25-tooth rear gear) than the 39, corresponding to 14.7%.

In conclusion, the test has shown that, when pedaling at a certain wattage, the effort is more sustainable with a higher cadence, allowing for a slight power saving at the same speed. But the real savings occur at the energy and muscular level, where the use of less torque (the force applied to rotate an object around an axis) allows for better long-term performance.