It is a 9-speed chain. It was really loose, slapping excessively. I can put 2 or 3 links back and see if it makes any difference.

OK, so I'll ask a silly question: is there a difference between a 9-speed chain for a road bike and a 9-speed chain for a mountain bike? I don't think so, but I may be wrong. It's a Shimano CN-7701 chain which is supposed to work with both XT (MTB) and Ultegra (road) groups - is there are reason it wouldn't work properly with a lower Deore group? I have Deore HG-50 cassette.

Adam