Originally Posted by duongrn
How much of a risk would it be that the chain fall off the front? Has it happened to you? Would it most likekly drop when I making shifts?
Thank you.
It'll probably happen often enough that you'll want it to stop happening.
I tried it once, and my chain fell off 2 or 3 times per mile. This was in Brooklyn, NY, where there are plenty of potholes, and I was riding an old Cannondale, which is the stiffest frame I've ever ridden. I would regularly lose water bottles on that bike, too. So, there are some variables, but I think that even on the smoothest roads you're asking for trouble if you don't have a front derailler, especially with a small chainring that may have different tooth profiles to facilitate shifting.
If you don't want to use a front derailler, maybe you could get a couple of cyclocross-style chainring guards like this:
http://www.peterwhitecycles.com/Cyclo-Cross.htm
You don't have to pay 40 bucks each for them, though - if you can scrounge up a couple of old chainrings and some beer, you can spend an hour filing the teeth off and fitting them to your crank so that the chain doesn't rub them.
Good luck!