Singlespeed & Fixed Gear - Chainring/Crank question

I have a Bianchi fixed gear conversion. I had a worhtless crank on that i bought for $25 because i was so short on cash. I just got a stronglight crankset a few weeks ago. I got the crank on but I can't seem to get the chainring to fly stright thus my chain falls off after about a block of riding. If i spin my crankset without a chainring on it, it spins straight. Once I put the chainring on, it doesn't spin straight. What pattern am I supposed to tighted the bolts on my chainring? I think that's the problem, if it isn't does anyone else know what I'm supposed to do?

I'm not exactly sure what the problem is, but here's a resource on chain tension that may help:
http://www.sheldonbrown.com/fixed.html#tension

there is not a "pattern" to tighten the chainring bolts but it never hurts to start with one and go across to another one and so on. if you look down at the chainring from above while it is spinning does it move side to side? sometimes a bike shop can fix this if not too bad.

I was told you need to do it in a certain pattern.

Yeah, it moves from side to side when the crank is spun

there is not a "pattern" to tighten the chainring bolts

screw one. skip two!

+1

Sheldon on chainring bolts:

"Tighten the stack bolts in a regular pattern, like the lug nuts on a car wheel. My standard pattern is to start by tightening the bolt opposite the crank, then move clockwise 2 bolts (144 degrees), tighten that one, clockwise 2 more, and so on. Never tighten two neighboring bolts in a row. You may prefer to go counterclockwise, but try to get in the habit of always starting at the same place and always going the same way. This reduces the chances of accidentally missing a bolt."

Once you get your chainring issues sorted out, if you're still having a problem throwing the chain, I'd suggest you investigate your chainline. As in, how straight is it? Pretty critical tweak on a fixed-gear.

Please check the width of your bottom bracket.

The Stronglight track crank requires a 108mm spindle.

If you have a longer or shorter spindle, it could put your cog and chainring so out of line with each other that your chainring would throw the chain.

Sounds like your chainring is bent.

Or you aren't using stack bolts (chianring bolts) for a single chainring.