Compact cranksets started appearing on road bikes in the mid-2000s. It’s hard to believe that 20 years have passed since their inception. Their onset revolutionized road cycling and opened the category to a wider audience, improving rider performance and enjoyment overnight.
If you’ve been grinding gears for a while now, struggling to make it up some of your area’s moderate to more challenging climbs, you should consider switching to a compact crankset.
So what is a compact crankset, and how is it different from a standard crankset?
Compact vs semi-compact vs standard crankset
A compact crankset uses a smaller front chainring combination (50/34T) than a standard crankset (53/39T). A semi-compact crankset falls in between the two.
The differences between compact, semi-compact, and standard cranksets can be summarized in the table below.
| Crankset size | Front outer ring | Front inner ring | Cranksets availability |
|---|---|---|---|
| Compact | 50T | 34T | All Shimano 10, 11, 12-speed All SRAM 10, 11-speed All Campagnolo 11, 12-speed |
| Semi-compact | 52T | 36T | All Shimano 10, 11, 12-speed All SRAM 10, 11-speed All Campagnolo 11, 12-speed |
| Standard | 53T | 39T | All Shimano 10, 11-speed All SRAM 10, 11-speed All Campagnolo 11, 12-speed |
| Standard (new) | 54T | 40T | Shimano Dura-Ace (12-speed) |
Shimano no longer offers standard (53/39T) cranksets for all its 12-speed groupsets. The 12-speed Dura-ace replaces it with a newer, 54/40T combination.
When SRAM introduced its 12-speed AXS groupsets that use the X-Range gearing, the front chainrings had different combinations, such as 50/37T, 48/35T, and 46/33T.
Why use a compact crankset?
More low gears for climbs
Most of us need help on the lower end for moderate to steep climbs; a compact crankset will do that.
Combining a compact crankset with a larger cassette, such as 28T, 30T, 32T, and 34T, allows you to go up steep hills while maintaining a respectable cadence.
The versatility of compact cranksets makes them a standard on road bikes since they provide the best of standard road racing doubles and touring triples. As amateur cyclists, we typically ride less than 30mph (48kph). We can maintain a higher and more efficient cadence while losing minimal top speed with a compact crankset.
Jeff Solomon has developed a visual representation of gearing differences between a compact and a standard crankset. Play around with the gearing combination to visualize them.
A tighter gear spacing
Besides a wider range of gears, compact cranks allow for tighter rear cassette spacing, which means less violent cadence jumps and more subtle changes in power when shifting.
When you start to fatigue, you typically only need a small change to maintain speed. A tighter gear spacing with a minimal jump of only one or two teeth between gears on the rear cassette can make or break your cadence.
Compact gear ratios offer fewer redundant gears and less overlap. This means you have more useful gears to choose from and spend more time with your chain in a straighter line with your cassette.
Minimize front shifts
A 50/34T compact crankset lets you handle more hilly terrains without shifting to the small ring.
For example, when I’m feeling good, I can get away with the 50-25/28T to power it over smaller climbs or rolling terrains. Minimizing front shifts reduces wear on the chain, chainrings, and front derailleur and creates fewer opportunities for the chain to drop.
More reading : How to Shift Gears on Road Bikes
Save some weight
If you’re running a standard or a triple chainring, switching to a compact will save weight simply because it requires less material to fabricate them. Fewer teeth mean smaller diameters that require shorter chains, so you save some weight from the chain as well. The total savings can be somewhere between 50g to 100g.
FAQ
Can I use compact chainrings on my current setup?
It depends on your current crankset setup. You can convert to a compact chainring if you use any of the crankset designs below.
- Five-bolt. Check your spider’s BCD (Bolt Circle Diameter) if you’re using the older five-bolt spider design. The BCD is measured between the center of the chainring bolts. BCD measurements for a five-bolt system are typically 110 for compact (50/34T) or semi-compact (52/36T), and 130 for standard crankset (53/39T, or larger).
- Shimano Hollowtech 2 (4-Bolt) crankarm can be used for 50/34T, 52/36T, 53/39T, and 54/40T (12-speed) chainrings.
- SRAM AXS (12-speed) crankarm can be used with 46/33T, 48/35T, and 50/37T chainrings.
- Campagnolo 4-bolt crankarm (11 and 12-speed) can be used for 50/34T, 52/36T, and 53/39T chainrings.
Do pro cyclists use compact cranksets?
Compact cranks aren’t just reserved for recreational cyclists. The pros use them too on ultra-demanding and long-distance hilly stages in races such as the Tour de France, Giro d’Italia, or Vuelta Espana.
Retired climbing sensation Alberto Contador rode with a 34T inner front chainring and 12-32T cassette. Now you know how he made his victories look so easy.
Are new bikes equipped with a compact crankset?
It depends on the value of the bike and its use. Low to mid-range road bikes usually come with a compact crankset. Mid to premium-range road bikes often come with semi-compact cranksets (52/36T). The popularity of standard cranksets (53/39T) is slowly declining and is only seen on pro cyclists’ bikes these days.
Alex Lee is the founder and editor-at-large of Mr. Mamil. Coming from a professional engineering background, he breaks down technical cycling nuances into an easy-to-understand and digestible format here.
He has been riding road bikes actively for the past 12 years and started racing competitively in the senior category during the summer recently.