Decided to weigh myself naked and then fully kitted up plus my bike with everything I'm taking which included old batteries (I'd guess 10-15 pounds worth) that I was taking in for recycling.
Naked = 183.4 pounds
Loaded = 236.5 pounds
Difference = 53.2 pounds
While I could feel the added weight when taking off or climbing it really wasn't all that bad. Of course I didn't go for any personal records. I forgot to weigh myself without the batteries to see how much they really were. This was with my commuter bike that has full fenders, rack and panniers.
Which is why I scratch my head when guys on bike forums go on ad nauseam about shaving a few grams here and there. Heck, even if we're talking about a pound or two - how much difference can that make to the overall mass of bike plus rider plus kit (even if you're not hauling batteries)?
It all depends on what your goal is. If racing for seconds then I can fully understand it but for the guy that is 20 pound over weight, not a chance.
Do a 20km (or more) climb @ 5% (or more) and you may wish your bike was 1 (or more) pound(s) less. That little bit of energy saved is energy you will need closer to the top of the climb. Again, this is only important if you are riding competitively. I think the difference in weight between my two bikes (before I put anything in the panniers) is around 5-7 pounds. When climbing normally (IE: not trying) I'm sure my speed is nearly identical. But when I race to the top for every last second, I prefer to do that using my race bike.
Weight does make a difference. If you care or not, that is up to the rider and their wallet.
Does the "not a chance" apply to all that follows if we are talking about a rider 20lb or more overweight? Or just a fit dude whose trim body mass is somewhere around 190 lb.?
Where I see the comment come up most frequently is not in the context of serious racers (sure, they are going to agonize over a few grams) but guys asking about which bike they should buy, and the resounding and near unanimous view being that the saving of around a pound in overall bike weight is a really big freaking deal. Now again, not talking about racing - the guy on a forum buying his first road bike is unlikely to be about to race it. But given that a full water bottle weighs more than a pound anyway, I still scratch my head. Even the pros carry one of those, if not two.
Maybe when I am trying to set personal best times sprinting up steep hills I will come around to the viewpoint that 1 pound matters.
But I'll probably REALLY want my water bottle after such at attempt.