[tzortn]

If you think that you will usually have a power source i would go with a corded model. We used a cordless impact wrench in the pits because we did not always have power. It does ok, but like Mojoe said it can suck a battery down pretty quickly. We only used it to get the transmission apart which was usually less than 3 times a day. We always did the wheels by hand because we did it so often.

[Mojoe]

If you already have a hammer-drill, just use that....or a regular drill. I know it doesn't have the torque of an impact, but on a bike you don't really need all that much torque, do you? Personally, I would go with an electric wrench/rachet before an impact. It is more of a time thing than strength. Use the rachet manually to break it loose, then use it to spin off off the nut or bolt. Especially something like front rotors. 10 bolts makes for alot of cranking.

[SlipKid]

Either way, you're probably going to want to get a good 18" breaker bar to loosen those stubborn fasteners (so you can speed it the rest of the way off with your nifty new tool). I have an older corded B&D unit and a couple of pneumatic wrenches, and still have to resort to the ol' breaker bar every now and then.

If I were to venture an opinion on corded versus cordless, I'd go corded unless portablility was a major criteria...