Recently, my chain has become so stretched that it is now at the very end of the dropout. I haven't thrown the chain yet, but I am worried about any problems that may come because of the current tension.

Should I remove a link so I can adjust the tension? Would this compromise the total integrity of the chain? Should I purchase a new chain?

I'm riding from San Diego to Los Angeles this weekend and I'm trying to get all my eggs inside of a basket or whatever.

you should have purchased a new chain several months ago.
now you probably have to replace the cog as well.
and maybe even a chainring.

Take a link out for now, it certaintly won't hurt.

Yes. Buy a chain before you do that ride. It is long walk though Camp pendleton with a broken chain.

get a new chain. $12 well spent.

it'll probably need a new chain, cog, and chainring, the sooner the better.

why you need to buy a new cog and chainring as well?

the "stretched" (worn) chain is longer and doesn't fit into the teeth correctly. So it wears on the teeth until it does.
i'll let sheldon explain it better.
https://www.sheldonbrown.com/chains.html#wear

I know this can be true with geared bikes, but I don;t know if this applies to a fixed gear set up.

it should especially matter on a fixed gear setup. since the chain is only ever on one ring and one sprocket, the noticible wear will be accellerated. not to mention that the wear happens during pedaling and when applying backpressure.

if the chain is stretched that badly, the op will most definately need to get a new chain, chainring and cog and install them together. a single new part will wear fast and mimic the old wear pattern. a new chain is going to be noisy and rough.

God. Dammnit. Yeah, it's my fault for not being vigilant about monitoring my drivetrain, but still. ****.

I know I'm not going to be able to afford a new cog and chainring, but I can afford the chain. If I go through with using a new chain on the old setup, what will I risk? I really want to ride this weekend and I kind of don't have a choice, as trains don't run on the weekend.

This brings another question to mind; how often do you replace your chains? Furthermore, how often do you replace your chainring and cog?

amtrack runs every day.

Ah, I was looking at metrolink.

Replace the chain first. If it runs over the ring and cog smoothly, you're fine. If it skips around and makes bad noises, replace them. Replace the chains when they stretch. You can check it with a special tool (most LBSs will do it quick for free in hopes that you buy a chain) or you can measure it. A new chain will have a pin every half inch on center. In 12 inches if you're not even landing on a pin, get a new chain. If you're using a singlespeed chain with no bushings they should last longer than your average multispeed chain. Replace the ring and cog when the new chain doesn't work smoothly on the old gears.

I am not sure how bikes get handled on Amtrak. I think a lot of people probably take the train as opposed to riding Freeway. last time I checked civilians are allowed on Camp Pendleton. Pre 9/11 there was a trail. I think they may have closed this pathway.

am i missing something here? a new chain is so cheap how could you let it get to that point?

You see, I am what you would call "new" at this thing. The only person helping me at the time was my dad who focuses in road cycling. Specifically speaking, he is a roadie; I guess chain wear is far less accelerated when riding with multiple gears and he failed to warn me of any such thing.

Also, I am an idiot. A lot.

For me it's not a money issue so much as a "I'll fix that later" kind of thing. Later takes a long time to come, sometimes.

Yeah, I'd agree. "ALOT"

You can always flip the chainring over when you put on the new chain. However, if the teeth on the cog are noticeably worn, then best to just take out a link on the stretched chain, and start saving for a new drivetrain.
putting a new chain on worn teeth is worse than keeping the old chain.

If it is indeed that worn, it's better (safer) to replace nothing than just a chain. If you replace just the chain, I guarantee you'll toss it on that ride, probably within 2 blocks. If you haven't tossed the chain yet with your current setup, remove a link, reposition your wheel, and replace everything as soon as you can.

This is the route I have taken. Many thanks to everyone that gave their input.

Dumbest thread of the week for sure. If you're experienced enough to know about "chain stretch" (which is actually just the pins developing grooves on either side of the chain), then you certainly should know that by the time it elongates to a noticeable point, it should've been replaced long ago!

I don't even use a ruler for chain wear. I use an 8.5x11 piece of paper. I measure the distance from one link to 11 away (using the 11in side). If I eyeball about 1/16th of an inch wear, I replace. A cheap 1/8th chain is only $10 around here.

Park makes a wonderful chain checker that measures for either .75 or 1 mm stretch, which if registered means "CHANGE THE CHAIN BEFORE YOU WRECK YRSELF."