What is a drive train?
The drive train on your bike is the system that moves you forward. Pushing on your pedals turns the chain, which in turn moves your tires forward. There are many moving parts that contribute to it, but that is basically what it boils down to.
For many years bicycles only had one speed. There were no shifters or different gears on bicycles. From 1817, when the bike was first invented to 1905 when the first gears were placed on a bicycle, you only had one front ring and one back ring.
In 1905 a Frenchman named Paul de Vivie invented and installed the first rear derailleur on his bike, making his cycling in the Alps easier. It allowed him to change between an easier gear for climbing, and a harder gear for flat sections. Since then the development of both the front and rear derailleur has been a constant advancement. As in most things related to vehicles, racing has been the major driving force behind the technological advancement.
Along with the development of the derailleur for changing gears, the rear sprocket or cassette, has been increasing in size. Most bikes will have anywhere from a 5 to 9 ring cassette (commonly referred to as the “speed” of your bike, ex: I have an 8 speed bike).
Now the most common on higher end mountain bikes is a 10, or 11 ring cassette. There are also 12 ring cassettes that are becoming more prevalent. The major driver behind this shift has been the adoption of the single ring chain ring.
Why There are 1, 2 and 3 front rings
The modern bicycle usually has a front chain ring group, with anywhere from 1 to 3 chain rings. These start with the smallest ring closest to the bike, and the largest ring farthest out. The picture below has only 2 chain rings, making it a 2x (2 by) system.
The major advantage of having 2 or 3 front chain rings is to make it easier to find the optimal gear for the terrain you are on. Having up to 33 gears to work with can make it easy to find a gear to make your pedaling hit the proper efficiency.
There are some drawbacks to having all those gears though. Some of them are technical problems, and others are technique problems.
Having all those gears can both be a blessing and a curse. It is great that you can have so many choices at your finger tips. It can also be tedious to try to find that perfect gear, getting the right combination of front and rear gears.
There are also many more moving parts to deal with on your bike. The front derailleur, in my opinion, is one of the most fragile and hard to adjust parts on your bike. It can very easily be knocked out of alignment, and is difficult to adjust properly.
The adoption of the 1x (1 by) drive train
The adoption of the 1x drive train has been a steady progress. It was always possible to convert your system to only use one front chain ring, but there were drawbacks.
The development of the narrow wide chain ring has changed that though. It uses alternating tooth sizes to help hold the chain in place. In the old system the chain is pulled back onto the ring by the spring in the rear derailleur and held there by the clutch mechanism. The front derailleur holds the chain on by using spring tension as well as tight clearance tolerances.
Converting to a single front ring with a narrow wide profile has many advantages:
- Reduces weight in the system. With no front derailleur you do not need the handle bar shifter, or the cable. You also love 1 or 2 rings.
- Simplifies maintenance, there are less parts to clean, adjust and repair.
- Reduces noise by not having as many moving parts.
- Stops dropped chains almost entirely.
There are a few disadvantages to using a single chain ring though:
- Loss of gearing range, making it harder to find the perfect gear.
- Less confidence that you have the right gear for the job. This is very rider specific.
Why this trend is not going to go away
The 1x drive train is here to stay. The simplicity, weight savings and ever improving technology is going to make this the drive train of choice for both recreation riders and racers alike.
In my opinion there are way too many advantages to this system to warrant using more chain rings up front. The old style 2x and 3x systems will stay around for a while longer though. They still do have some uses, and the components are typically less expensive, making them much more prevalent on entry level bikes.
I am very excited to get my next bike, which will have a 1x drive train installed. It is going to be so much easier to find a gear, and I am excited for that simplicity. If you want more to read on this subject check out my post on how to shift your bikes gears.