Last night I went to bike class #2, intermediate mechanics (yes, different shop than the bike kidnappers).

Even if you’re never going to work on your own bike, it doesn’t hurt to have a vague idea how things work. Kind of like your car- you may not change the oil yourself, but you do know that your car uses oil, it needs to be changed, and it’s under the hood.

The most useful thing we talked about last night was probably adjusting the derailleur. (I’m biased- I think this is important because it’s one of the things that contributed to my chain falling off during the triathlon.)

Let’s go over some parts, shall we?

bike diagram

A sprocket is one of the round, spiked-looking disks the chain rests on. Each sprocket is a different size- the smaller the sprocket, the higher the gear. The cassette is the whole series of sprockets together.

The derailleur is what knocks the chain from sprocket to sprocket when you change gears.

A silly but useful analogy is that it’s like derailing a train- it knocks the chain off the “track”.

There are front & rear sets of all of these things. (Cassette, derailleur, etc.)

bike cassette

These are the adjustment screws- they let you adjust the derailleur from side to side so the chain lines up with the sprockets correctly.

adjustment screws

The “H” is referring to the high gear, which is the smallest sprocket. The “L” is talking about the lowest gear, or biggest sprocket.

[Got that? High gear = small sprocket and vice versa. High gear = harder to pedal. Still confuses me sometimes.]

Adjusting these screws essentially sets limits for where the derailleur is lined up in the highest & lowest of gears.

How do you know where it should go? If you stand at the back of your bike and look down the length of the derailleur, the chain should be centered in the middle. (On the same plane.)

front adjustment screws

Those are the screws to adjust the front derailleur.

So the screws set the alignment for the highest & lowest gears- what about all the gears in the middle? Then you need to adjust the cable.

But we’re confused enough now. We’ll stop there. 😉

Do check occasionally and make sure your derailleur isn’t bent– it can lead to disastrous events: If the derailleur gets to close to the wheels, it can hit the spokes and rip the whole thing off- if you’re lucky. If you’re not lucky- it’ll bend your entire bike frame & then you’re screwed. So it’s worth checking, ok?! 😉

Chances are you don’t need to know this, but do get familiar with changing a tire. I promise it’s not hard, and you never know when you might need to do it!

Bike update: the person I need to talk to won’t be back til Saturday now. Humpph. Guess who goes out of town Saturday? Yeah, me. 🙁