Tech

Choosing your Drivetrain – part one Derailleur Systems

Choosing between modern bicycle drivetrains

You have in all likelihood owned a bicycle with either a derailleur system or an internal hub transmission. All bicycles have some form of transmission, which literally means a way to transmit your power from the pedaling motion of your legs to the rotation of the rear wheel, propelling you forward. In other words, even a single speed bicycle has a transmission, simple as it is.

Today we have more viable bicycle transmission options than ever before, and that can make your decisions difficult when it comes to purchasing your next bike. This series of articles is an attempt at helping you make an informed choice that makes the best sense for you. We’ll break the choices down into 3 different groups, and then show you pros and cons for each type.

multi-driveline

1. Derailleur systems-

This is the most common bicycle transmission, popularized by the “10-speed bicycle” that was prevalent in the 1970’s. A derailleur transmission has a chain and multiple sprockets. For example, the 10-speed of the 1970’s had 5 rear sprockets and two front sprockets. The derailleurs move the chain from one sprocket to another, causing each pedal rotation to rotate the rear wheel a little more or a little less.

In the 1980’s, touring bikes and mountain bikes typically had 3 front sprockets and 6 or 7 rear sprockets, for a total of 18 or 21 “speeds”. In the 90’s we saw the number of rear sprockets (or cogs)increase to 9, while 2 or 3 front sprockets (or chainrings) remained standard. Now it’s common to see 10 or 11 rear sprockets. Two or three front sprockets are still common, while the current trend is to decrease the number of front sprockets while increasing the number and size of rear sprockets.

Pro:

1. When operating optimally, a derailleur system is the most efficient

2. Lowest cost, most widely available worldwide. There are more derailleur systems to choose from and more manufacturers making them than any other transmission type. This includes some excellent ergonomic controls for operating shifting and braking with ease from the same lever.

3. Everything is external, so when problems develop, they’re easy to diagnose and repair, relatively speaking

Con:

1. Everything is exposed, so a derailleur system is vulnerable to environmental concerns, such as weather, dirt, dust and foreign objects getting jammed in the system, etc.

2. All derailleur systems use chain, which requires regular cleaning and lubrication. A very dirty or rusted chain represents a significant efficiency loss.

3. Shifting is not self-explanatory and non-linear. That is, if you have 30 gears from which to choose, and you want to shift from your 18th lowest gear to your 19th, you may be shifting your rear derailleur across 5 cogs and your front derailleur to a different sprocket to do so.

4. You must anticipate your shifting. Some shifts are difficult or impossible to complete under load. This can be quite frustrating when encountering a sudden change in gradient.