Types of Cranksets
Compact Vs. Standard Cranksets - The Differences
Compact or standard? That is the question when it comes to bicycle cranksets. There are advantages and disadvantages to both along with obvious reasons why you should consider one or the other.
The difference between these two types of road cranksets comes down to gearing. Which one you choose ultimately determines whether you’ll have more top-end speed or accelerating/climbing power. In this Compact vs. Standard Crankset Guide, L9 Sports looks in-depth at when and why each style works best. We also provide a bicycle gear chart to compare the speeds of each at different cadences.
Bicycle Crankset Basics
Standard and compact cranks have different chainring sizes due to a different BCD, or “bolt circle diameter”. (It’s also known as pin circle diameter or PCD.) This is the size of the circle formed with the bottom bracket axle at its center and the edges passing through the center of the chain wheel pins. As the name suggests, compact bike cranksets are smaller than standard cranksets, which changes the gear ratio.
Standard cranks are often called racing cranksets because they offer the fastest common gearing (bigger chainrings are available but must be bought separately). Standard cranks have 53/39 gearing, meaning they have a 39-tooth small ring and a 53-tooth big ring. The ring is short for the chainring, which is what the front gears are called that are bolted to the cranks. The BCD of standard cranksets is 130mm. This is ideal for road races on relatively flat terrain and riders who like to go as fast as possible.
Compact cranks have a smaller BCD of 110mm, which allows for smaller chainrings. Compacts have a 50/34 gearing, losing three teeth on the big ring and five teeth on the little ring compared to a standard. Compact cranksets are preferred for climbing races or for people who like to ride fast but not a race. There are many people that race compacts, but for most people, it's not the preferred crankset for flatter races or any with limited climbing.
Gearing Options For Bike Cranksets
When combined with a wide-range rear cassette, like an 11-28, compact cranksets offer a wider range of gearing and —- as mentioned earlier — are really designed to maximize one's efficiency to climb or travel at lower speeds. More recently, long-caged rear derailleurs have been more common in use with compact cranksets and 11-32 cassettes, such as SRAM's WiFLi system. This wide range of gearing means a wider range of comfortable speeds and decreases the gearing overlap (when different combinations of front gearing and rear gearing have the same gearing ratio such as a 50/25 and 34/17, both of which are 2:1 gear ratios).
Standard cranksets have more gearing overlap, which can be preferred for racers so they have similar options in the middle of the cassette for both chainrings. This allows for things like shifting into the big ring early if they think an attack might happen so they're prepared to jump to faster gears. Conversely, they can be going at a pretty fast speed in the little ring when approaching a climb and shift to easier gears as necessary. Racers tend to want more options in a certain range of gearing. That's also why some racers elect to use an 11-23 close-range cassette instead of something with a wider range — because the gap between gear choices is smaller for certain shifts. This makes it easier to maintain a preferred or optimal cadence which maximizes efficiency.
|Cadence (RPM)||Standard 53x11 Speed (MPH)||Compact 50x11 Speed (MPH)|
A standard 53-tooth chainring paired with an 11-tooth rear cog (fastest rear gear) gives speeds as listed when using a standard 700x23 tire. All of the speeds were calculated using a free software app from Bareknuckle Brigade called Rabbit. In the same table, we compare the fastest combination for a compact crankset, in which a 50-tooth front matched with the 11-tooth rear.
As you can see from this road bike gear ratios chart, very high speeds can be obtained with a standard crankset — but you can still get moving right along with a compact crankset. Most people are not going to be able to travel at those speeds riding solo, so a compact is a good choice for those who do a lot of solo riding. You will also notice that at 120 RPM, you're only giving up 2.6 MPH, which is not much at all. Pedaling down a hill or in the final sprint of a race is when this would become a factor. Most people would have stopped pedaling at this point and would just enjoy the free speed.
How slow can you go with a standard crankset, though? In the first table here, we show the lowest speeds using a 39-tooth ring paired with a 26-tooth rear cog, which is very common (25-tooth also being very common for racing cassettes). The second table uses a 28-tooth cog, which is the largest rear cog you will see on most road racing bikes and is generally reserved for races with some decent climbing. We also do the same with the compact crank using the 34-tooth front ring matched up with the same size rear cogs.
When looking at the slow side, the difference between a compact and standard using an 11-26 cassette is 0.9 MPH at 60 RPM (grinding up a hill) or 1.2 MPH at 80 RPM (seated climbing). For an 11-28 cassette, we have a difference of 0.8 MPH at 60 RPM and 1.1 MPH at 80 RPM. This demonstrates the ability of the compact crankset to keep moving at lower speeds, which is important for serious hill-climbing.
|Cadence (RPM)||Standard 39x26 Speed (MPH)||Compact 34x26 Speed (MPH)|
|Cadence (RPM)||Standard 39x28 Speed (MPH)||Compact 34x28 Speed (MPH)|
|Type||Top Speed w/11t (MPH)||Low Speed w/26t (MPH)|
|Standard||41.4 (110 rpm)||9.4 (80 rpm)|
|Compact||39.1 (110 rpm)||8.2 (80 rpm)|
Full-Range Comparison at Comfortable Seated Cadences
To put this into perspective, that's a 12.8% difference at 80 RPM in your ability to go slower, but only a 5.6% loss in your top speed at 110 RPM — if you can even get to those speeds. You can see why a compact crankset is appealing to those who spend a lot of time climbing hills or those that rarely spend time over 30-35 MPH. Use this information to find the right bicycle crankset for how you ride. L9 Sports has a crankset for everyone with a low-price guarantee.