MTB Race News Gear
Buy It Here!
Shirts, Socks, Hoodies and More...
Home Calendar MTB RaceNews Team Photo Gallery About Us
search:

Coach's Column: Pros and Cons of the MTB Drivetrains

Posted by: Shannon Boffeli |February 20, 2014 3:35 AM

Coach's Column with Andy Applegate: Pros & Cons of the MTB Drivetrain Options - What is Best for You


Question: I'm putting together my new race bike for next season, with so many drivetrain options what are the pros and cons of the different setups, i.e. 3x9 vs. 2x10 v. 1x11?  Is certain gearing more appropriate for certain focus i.e. endurance, short xc, etc.?  

Answer:Interesting question. The drivetrain options available now are numerous and could be a little confusing. Let’s try to look at it from a rider or coach perspective. First, we can most likely omit the 3x9 option for a new bike. Going forward, high end 3x9 gruppos will soon be discontinued. While you will probably be able to get parts for 3x9 for years to come. New groups will be hard to find and most will be in the lesser quality component ranges.

That leaves us with 2x10 or 1x11 as choices. Both are certainly viable options and work really well. However, it seems like we have had a glimpse of the future of MTB gearing this year and it looks like the front derailleur will be going the way of the dinosaur.

Before we go any further, think carefully about the demands of the terrain you are most often riding and what your goal events require. Competing mostly on fast Midwest singletrack? Or will you be doing more steep or long climbs? Do you require a very small "granny gear” for climbing or do you need a big gear to pedal at high speed? Keep in mind that with 2x10 (and even more so with 3x9) there is a lot of gear "redundancy”. In other words, you don’t really have 20 discrete, different gears, as many are repeated. Several of the small ring/ small cog gear combinations come very close to matching some of the big ring, big cog combos.

Next, let’s consider the "hardest” and "easiest” gearing on a couple different set ups. I guess this requires a little bit of a definition of gear "development”. Gear development is the distance your bike will travel with one full revolution of the cranks in a particular gear combination. The further the bike travels (bigger gear development) the "harder” the gear. We don’t really need to talk in specific numbers to make comparisons here though, we really just need to know which combinations are bigger and which are smaller. Let’s look at some numbers.

Here are some easiest gear possibilities first (these numbers assume a 29in wheel and a 2.0 tire)

Common 2x10 set ups

26x36 gear = 1.6 meters development

24x36 gear = 1.5 meters development

Common 1x11 set ups

34x42 1.8 = meters development

32x42 = 1.7 meters development

30x42 = 1.6 meters development

Common 3x9 set up

22x34 = 1.5 meters gear development

As you can see there is not as much difference on the low end as you might expect. Depending on what size ring you choose, you can get easy gearing with 1 or 2 ring set ups. You can even get the same easy gear as a normal 3x9 set up (22x34) with a 24 tooth ring on a 2x10 (24x36).

Next let’s have a look at the opposite end of the spectrum:

2x10

39x11 = 8.1 meters

38x11 = 7.8 meters

1x11

34x10 = 7.7 meters

32x10 = 7.3 meters

30x10 = 6.8 meters

3x9

42x11 = 8.7 meters

Now we are really seeing some differences. This is where the real compromise needs to be made when you are going with a 1x11 over a 2x10 or even 3x9. The question is: how big of a gear do you really need? Again, it comes down to the terrain you will be riding most. For easy gears you really can go with either set up, but you might need to swap rings from some stock offerings to get what you need. For the high end, with a single ring you are going to lose some development, but how often are you spun out in your hardest gear on the MTB? For most of us it is not very often, however if you are riding a lot of flat dirt roads and the like this is a consideration.

Pros and cons of a 2x10 set up:

On the plus side, you get both high and low gearing without compromise, there is a greater variety of price point options, most wheels are equipped to handle 2x10 cassettes

On the negative side, you still have to deal with the front derailleur and shifter and generally the system will be a little heavier

Pros and cons of a 1x11 set up:

On the plus side, no more front shifter and derailleur to worry about setting up! System is generally lighter. In wet and muddy conditions the single ring setup could be less problematic than multiple chain rings and a derailleur.

On the negative side, available options are still limited and quite expensive, compromise needs to be made on gearing particularly on the high end. Wheels may need to be adapted to take the 11 cog cassette. Wider range cassette means bigger jumps between gears.

There is a lot of good news on the way. There are a few companies making adapters to fit a 42 tooth cog on a 10 speed cassette so you can run a 1x10 with a gear spread similar to the 1x11 systems. I would also expect the 11 speed technology to trickle down to less expensive groups.

Either 2x10 or 1x11 will work very well across a variety of MTB disciplines (xc, endurance etc.) but be sure to look closely at the gearing you will end up with. Pay specific attention to the high and low gears and the compromise that you may be making. There are plenty of online gear calculators to easily do this. In general, for most off road applications I would pay more attention to being sure you have the easier gear you need to get up hills even if it means a trade off in the high end. Keep in mind that if you are racing shorter XC type events you may be able to get away with a harder gear combination. Crushing a slightly bigger gear than comfortable up a short climb in a 2 hour or less race is not much of a drawback. On the other hand if you are targeting longer races, having the easier gear to get up a climb after you have been on the bike for many hours could be the difference between having a great day or struggling just to finish.

The nice thing is that we have all these choices available and even more forthcoming.

Andy Applegate is a Pro level coach with Carmichael Training Systems. He has over 20 years of racing experience and has been coaching cyclists full time since 2001. His passion is endurance mountain bike racing. You can find out more about Andy and his training programs at www.trainright.com

Close (X)