After looking at tons of fixies/trackbikes/conversions I've noticed that some fixies (mostly the road conversions) have vertical dropouts while the true "track bikes" have the horizontal rear dropouts. This may be a dumb question, but what's the real difference here? I'm looking for a fixie to just commute and do some casual mid-distance road riding with.. does the dropout orientation really concern me?

Road bikes have horizontal dropouts (I'm assuming you meant horizontal instead of vertical. if not, you have a whole host of other questions to be answered) because, among other reasons, it allows you to quickly and easily remove the rear wheel to fix a flat. On a track bike, if you get a flat, your race is over, so the speed doesn't matter as much. The older road bikes also used horizontal dropouts to fine tune the handling of the bike. Placing the wheel at the rear of the dropout gave for a smooth, mellower ride, while putting the wheel at the front of the dropouts would raise the bb slightly and make the bike handle and sprint a bit more quickly. For a commuter, I FEEL, that horizontal dropouts are better. Its easier to change a tire, you can run fenders and still remove the tire without removing the fenders, and if you go with a single speed, you can move the wheel and the brakes will still line up.

oh that makes sense.. thanks.

ok.. so i guess i had my terms confused. horizontal dropouts are the ones that allow the wheel to slide out diagonally forward and down, while rear dropouts let the wheel slide out the back of the frame.. is that right?

yep

well, most people call the rear opening dropouts "track ends".

hopefully sheldon wont come around and give a beatdown for even refering to track ends as dropouts...the dropout refers to the wheel dropping out.. which track ends dont allow

personally.. i call em track drops all the time..i kinda like how upseting that is to purists

Theyre all dropouts...there are just different kinds.

Correct.
1 Newer Road and ATB's have vertical drop outs
2 Track backs have rear facing drop outs
3 Older road bikes used for conversions have a forward facing horizontal drop out.

hope that helps

to add more confusion, sometimes track ends
are refered to as "rear fork ends".

The rear-opening fork ends are a silly fad that has been running its course as part of the fixed-gear/singlespeed revival.

Actual dropouts (see: https://sheldonbrown.com/gloss_dr-z.html) permit easier wheel changes since you don't need to derail the chain to get the wheel out (that's where the term "drop out" comes from.)

Also "horizontal" dropouts are usually not actually horizontal. The well designed ones run at a slant roughly perpendicular to the seat stays. This permits you to adjust the axle back and forth in the slot without changing the distance from the axle to the brake shoes. If you want to use a flip flop hub to give two different gears, on a bike with a rear brake, this lets you do it without needing to fiddle with the brake shoes every time.

Some folks think the old-fashioned rear opening fork ends are somehow more secure against wheel slippage, but this isn't an issue if your axle nuts or quick release is secured properly.

Sheldon "Turn On, Tune In..." Brown

not correct..sheldon was a little soft on his clarification...i think i said before... drop outs drop a wheel out.. hence the name

but its like arguing the correct pronunciation or harassment..

does sheldon take acid?

um-err-ikan four-in pah-li-see