What octane fuel do you use?

once again, I am a newbie, and I dont know a whole helluva lot about bikes, so hear I go with another simple question. Should I always use 93 octane by default or is there some reason I should be using a lower octane?

The main reason to use a lower octane is the price.

Octane rating is misunderstood by a lot of people.
It does not change your gas mileage to use higher octane.
It does not burn cleaner.
It does not make you more attractive to the opposite sex. (Usually)

The way it works is the lower the octane, the BETTER it burns. Higher octane is more resistant to igniting.

What does this mean?

In higher compression engines, if the octane is too low (burning easier) sometimes the fuel will ignite before you want it to. (Actually from compression instead of spark) This causes the engine to "knock" or "diesel". If you ever took off from a stop in too high a gear on your bike, you probably have heard this unpleasant noise before.

Well, premium fuel costs more. It MUST be "better", right?

Wrong.
Calling higher octane fuel "Premium" fuel is really a marketing tool to get more money from your pocket to the gas stations cash register. The price of different octane ratings is negligible to the station, and the huge jump in prices between the grades is, you guessed it, almost pure profit.

What about the special additives I get with premium fuel?

Some companies add injector cleaners etc. to their fuel. It's debatable if this is worth the extra 20 cents a gallon for the minuscule amount of chemicals that actually make it to your tank.

Do I need to use 93 octane?

The best plan you can follow is use the lowest octane you can without your engine knocking. If you are using 93 octane, try mixing it with 1/2 a tank of 91. Does the engine knock? If yes, you are stuck paying the higher price. If no, try a full tank of 91 and repeat on down the octane scale.

Harley Davidson recommends higher octane fuel, but I run 87 in my Sporty with no knocking what so ever.

My two bits:

http://www.youtube.com/watch?v=ZZx5w1jVUDA

abatt, if you have an owner's manual, read it and see what they recommend. My C90T Suzuki takes 87 octane, and I see no reason to use anything else.

Also of note: If you are riding at high altitude, say in Denver, Co, You may notice that the gas stations sell even lower octane fuels than us flat-landers usually find.

It has something to do with atmospheric pressure.

CaptCrash I have to say that video was informative and entertaining. Good job!
And remember

"DON'T DRINK GASOLINE, IT WILL RUST YOUR PIPES!"

I've run 87 octane in every one of my bikes. I've never had a problem with it.