November 30, 2013 26 Comments
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).
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).
The Triple: Early 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.
The Double: Before 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.
The Single: Just 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. The Race Face Narrow Wide chainring design eliminates the need for a chainguide with 1x setup, but you are still left with what could be a less than desirable gear range.
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!