Bicycle Mechanics - Newb Question

So I had a minor crash last weekend and my gear shifting was off. My bike wasn't really shifting correctly before the crash either but the problem became a lot worse after it. For instance, I couldn't ride is some gears at all. I noticed (see picture) that part A (no idea whats its called) was not flush with part B (again, no idea what this is called). I took the bike to the shop, and without really knowing what they were going to do, left them to fix it. When I picked up the bike I noticed that these two parts were in fact, now flush. I went out riding and now notice again that these two parts arent flush again - but my gears shifted fine.

What is going on here?

Part A is supposed to move relative to Part B when you shift the front derailleur (that's what it's called). Their relationship will vary depending on which chainring your chain is on.

If the bike is shifting well, the shop did their job correctly.

Parts A and B meet at a pivot (visible just below your line for B, left of the 2 screws). B is fixed, bolted to your frame. A rotates along the pivot. When you shift to big chainring in front, the cable (end of which is visible just above the end of your A line) pulls, rotating A clockwise (from the point of view of your picture, bringing the point where your A arrow points down, and the front derailleur fork out. Shift to small chainring in front, opposite happens. So "flushness" only depends on what you do with the front shift control.

You have the control, mah man... You can flush the flushness, or unflush the flushness... It's your bike!

Stop agonizing and go ride.

Is that Medicaid Part A or Blue Cross/Blue Shield?

Kidding:

I would stop by my local bike shop or even Border Books/Barnes and Nobles/What-have-you. Visit the Sports section and leaf through the bike repair/maintenance books for a well-illustrated, user friendly book. One I noticed is by an author called Zinn (I don't know the name of the book, sorry). Just aquaint yourself with what's going on with your bike. Many adjustments can be made with a small tool in a minute or two without a trip to the bike shop. It can save you tons of cash and enhance your biking experience knowing that should you have trouble on the road, you won't have to call home for a ride.

You are on the right track. Please feel free to ask any question. I would advise doing a search and reading whatever posts have been out there that may answer your question first. But if you are confused, just ask. Noone really expects you to know it all.

They don't teach this stuff in grammar school, Ya know.

One I noticed is by an author called Zinn (I don't know the name of the book, sorry). Just acquaint yourself with what's going on with your bike.
The author is Lennard Zinn and the books are "Zinn and the Art of Road Bike Maintenance" or "Zinn and the Art of Mountain Bike Maintenance". They are very good

Is that Medicaid Part A or Blue Cross/Blue Shield?

Kidding:

I would stop by my local bike shop or even Border Books/Barnes and Nobles/What-have-you. Visit the Sports section and leaf through the bike repair/maintenance books for a well-illustrated, user friendly book. One I noticed is by an author called Zinn (I don't know the name of the book, sorry). Just aquaint yourself with what's going on with your bike. Many adjustments can be made with a small tool in a minute or two without a trip to the bike shop. It can save you tons of cash and enhance your biking experience knowing that should you have trouble on the road, you won't have to call home for a ride.

You are on the right track. Please feel free to ask any question. I would advise doing a search and reading whatever posts have been out there that may answer your question first. But if you are confused, just ask. Noone really expects you to know it all.

They don't teach this stuff in grammar school, Ya know.

Nice post, encouraging.

The author is Lennard Zinn and the books are "Zinn and the Art of Road Bike Maintenance" or "Zinn and the Art of Mountain Bike Maintenance". They are very good

Here, here to "the mighty (ZINN)." An excellent compendium of worthwhile information.

Pardon my partial plagarism of the song having the words:

Come on without, come on within,
You'll not see nothin' like the mighty Quinn.

The inane ramblings of a man with too much time on his hands... I must begin another bike build, restoration, tear-down; anything to stave off the symptoms of BIKEMANIA.

Thanks for your help guys.

The author is Lennard Zinn and the books are "Zinn and the Art of Road Bike Maintenance" or "Zinn and the Art of Mountain Bike Maintenance". They are very good

That's it. Thank you. I recall leafing through the book. It is very clearly illustrated and directions are simple.

Before you buy anything, I would suggest checking your local library for any bike repair books they may have. If the library has some, check them out and try doing some simple stuff on your bike using the manuals. Then buy the books that best match you and your bike.

Great idea. Some of the books you find in the library can be dated, so make certain that you can find your components in the book before taking the book out.