When it comes to choosing a crankset for the road, it seems like there are a million and one options out there, but the biggest question we get all the time is: what is the difference between a compact and a race crankset, and which one should I ride?
“Standard” cranksets, also known as “race” cranksets have a 53 tooth big chainring and a 39 tooth inner ring. Until recently, it was the only gearing option for road riders, unless they went with a triple. The chainrings mount on a spider that has a bolt circle diameter (BCD) of 130mm (Shimano, SRAM, FSA) or 135mm (Campagnolo). This combination gives riders a very tall gear, which allows them to go fast, but requires more strength to push so they are usually only used by more experienced riders, or those with very strong legs. Although even for strong riders the 39 tooth inner ring can make climbing very difficult, and few outside of the pro ranks can ride in the 53-11 combination. However, if you ride with a fast group or are looking to “Cat up” for racing, you may find the standard crankset to be ideal.
The compact crankset hit the scene a while back, and was immediately embraced by many riders. Compact cranksets have a gear combination of a 50 tooth big ring and a 34 tooth inner ring. The chainrings mount to a smaller 110mm BCD spider (for all brands). The compact crankset gives riders the ability to pedal with a higher cadence in an easier gear instead of always grinding away like you would with a race crankset. Compacts are ideal for riders who are more interested in enjoying the ride than going fast (although we have some folks at the office and in our stores who race on compacts…) or that live in very hilly areas. In fact, even some pro’s will ride compacts on very difficult mountain stages. The main drawback of the compact is how easy the gearing is. It’s not unusual for a rider on a compact to spin out his gearing on a downhill, and some riders find the 34T inner ring to actually make climbing more difficult because it forces them to pedal at an excessively high cadence.
A third option, and one that is increasingly being embraced around the office, is the mid-compact. The mid-compact splits the difference between a standard and compact by offering a 52T big ring and a 36T inner ring. The chainrings mount on either a 110mm BCD (Shimano, SRAM, FSA) or a special 130/135mm BCD (FSA, Shimano, Campagnolo) spider*. The biggest advantage of the mid-compact is that it gives riders a pretty high top gear thanks to the 52T big ring, while the 36T makes climbing much easier by offering a higher cadence than a 39T, but with more resistance than the 34T.
*If you want to install a 36T inner ring on an older 130/135mm BCD crankset, check with the manufacturer for compatibility.
A fourth, but little used, crank combination is the venerable 54/42T chainring combo, aka “The Flemish Compact”. You can still sometimes find this crankset combination, although it’s almost never spec’ed on a bike now except for some time trial bikes. If you’re an exceptionally strong rider who lives in an exceptionally flat area, you may benefit from using Flemish Compact. Otherwise, we’d recommend staying away unless your first name is “Roger” and your last name is “De Vlaeminck”. So, now for the question…if a 54/42T is a Flemish Compact, what is a Flemish Standard?
UPDATE: When we first posted this article, many of you asked about triple cranksets. The introduction of the compact crankset, 11-speed drivetrains, and mid-cage rear derailleurs has mostly rendered the triple crankset obsolete. Newer mid-cage rear derailleurs like SRAM’s WiFli system, or options from Shimano and Campagnolo, can now handle cassettes with up to a 32T big cog. An 11-32T or 12-32T cassette, when paired with a compact crankset, appears to offer about the same gearing range as a triple with less gearing overlap, less weight, less mechanical complexity, and a lower Q-factor. A few bikes (mostly touring models) are still spec’d with triples, but if you’re looking for a bike with plenty of gearing options, you may want to look at what the cassette range is instead of the crankset.
So which is the right crankset for you? Well…that’s really going to depend on your ability level, the terrain around you, and your experience. It you’re a very strong, very experienced rider, you’ll probably want to use a race crankset. However, for most riders the compact is just fine. While there is always the temptation on a bicycle to go as fast as possible, it’s important to remember that you need to work your way up to things—and that a bigger gear doesn’t necessarily equal bigger speed. Trying to push too big of a gear right off the bat can hurt your knees, lead to muscle imbalances, and just make rides more difficult and less enjoyable than they need to be. Especially for newer riders, or those without a lot of time to ride, proper form is more important than pushing big gears, and the compact is perfect for developing form since you pedal at a higher cadence. Over time, if you feel you are spinning out the compact crankset, you can always upgrade it with 52/36 or 52/38 chainrings to get more top end speed and a more comfortable climbing cadence.