1, 2, or 3: How Many MTB Chainrings Do You Need?

We’ve gotten a lot of questions from our customers lately about all the different drivetrain options available for mountain bikes. To help answer your questions, we turned to our in-house expert: Mark (some of you might recognize Mark and his mustache from our videos).

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Mark knows a thing or two about mountain bikes

If you are in the market for a new mountain bike or a new drivetrain for an existing mountain bike, then the crankset and gearing options can seem overwhelming and a little confusing. Triple crankset, a double, or just rolling with a single ring…which is the right one for you? Why would you choose one chainring over three or two? Can more actually be less? Let’s take a look at the options and when it comes time to upgrade, you will have a better sense of what will work best for you and why.

For years the traditional mountain bike drivetrain consisted of a triple (3 chainrings) crankset paired with a cassette (or freewheel) that has grown from 6 to as many as 11 cogs. Fast forward to now and you still have the triple (3x) crankset option, but you also have double cranksets with 2 chainrings (2x) as well as single cranksets with just one chainring (1x). 

This FSA triple crankset offers plenty of gearing options

The TripleEarly mountain bikes used whatever components were available at the time, and at that time it was primarily touring components. The wide range of a triple crankset was also necessary because the bikes were quite heavy when compared to today’s standards and the low range was needed to get those klunkers up the hills. Over time cassette ratios were refined and the gearing on triple cranksets became more compact, with smaller jumps between the 3 chainrings. Most current triple mountain bike cranksets have gearing in the 22/32/42t, 24/32/42t, or 22/32/44t range. A triple crankset typically offers the broadest range of gears, and depending on your specific needs it may be the best option for you. Good examples for using a triple would be large changes in elevation on your trails, riding to the trailhead via the road, or the desire to have a low gear that you can “spin” up the hills with.

This double crankset from Shimano offers a wide spread of gearing and reduced weight

The DoubleBefore double cranksets were embraced by component manufacturers, many riders would ditch one of the chainrings from their triple cranksets. Some people removed the large chainring to gain some ground clearance and because they didn’t need the tall gear that it offered, while others would get rid of the small ring because their terrain wasn’t hilly enough to dictate a gear that low – or they were just strong enough to do without it. Either way it was a compromise and the rider was losing some of the wide range that a triple crankset offered. When 10-speed cassettes were introduced to mountain bike drivetrains, double crankset gearing was optimized and the gear range was expanded to rival that of a triple drivetrain. The 2×10 speed drivetrain offers reduced weight, optimized front shifting, and a minimal compromise on overall gear range. Now that there are options at most price levels, a 2x drivetrain would be a great choice for anyone looking to shed some weight from their bike without giving up much in terms of versatility.

SRAM’s XX1 and X01 systems feature only one chainring and an 11-speed cassette with a huge gearing range

The SingleJust as riders were removing a chainring from their triple cranks, some were going a step further and removing the inner and outer ring and just keeping the middle ring. The reasons were numerous – further weight reduction by getting rid of the front shifter and derailleur, simplifying the drivetrain, and reducing some of the redundancy that comes with multiple chainrings. But like the early 2x adopters, they were compromising the versatility of their mountain bikes. Folks without much elevation change could get by with it, but the reduction at the high and low end of the gear range was significant. Another challenge of a 1x drivetrain is chain retention. Without the front derailleur to help keep the chain in place you need some sort of chain device to manage chain drop. It can be as simple as a road or cross style “chain watcher” if your trails are fairly smooth, but faster, rougher trails require a full-on chainguide to keep the chain on the chainring. Then came the 1×11 mountain bike drivetrain. Pioneered by SRAM, the 1×11 drivetrain offered the widest gear range for a cassette (10-42t), a narrow/wide chainring tooth profile to manage chain retention, and a rear derailleur with a clutch mechanism that also assisted with chain management by keeping more tension on the chain. This ushered in a 1x option for people actually riding in the mountains and significantly reduced the weight, friction, and noise of the drivetrain. The one caveat at present with the 1×11 drivetrain is cost – the technology is new and hasn’t trickled down to the lower price levels. If you aren’t overly concerned with the cost, there is a viable option for riders seeking a 1x drivetrain who don’t want to limit where they can ride.

Hopefully you now have a better understanding of how the mountain bike drivetrain has evolved over time, the available options, and why you might choose one over another.  If you ride in extremely hilly terrain a 3x drivetrain may serve you well without breaking the bank. If you are a stronger rider who wants better front shifting performance and less weight, you may opt for a 2x drivetrain. Or if you want the ultimate in light weight, less clutter, and smooth shifting check out a 1×11 drivetrain. Thanks for reading and enjoy the ride!

Our Take: Race vs. Compact Cranksets

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?

Race cranksets, also known as “standard” 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 race crankset to be ideal.

A race crankset from Campagnolo

The compact crankset hit the scene a few years ago, and was immediately embraced by many riders out there. 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 compact crankset from SRAM

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 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.

A mid-compact crankset from Shimano

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?

Roger de V has a good day riding a Flemish Compact

Roger de V has a great day riding a Flemish Compact

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.

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