Solo MTB about 26 – 27 lb with bottle racks and mudguards and b1g tough wheels
Tandem around 50lbs
My commuter around 30lb. Mrs TJs commuter around 26lb
All weighed on bathroom scales so accuracy will be low.
As for weight making little difference I was surprised how much it does make. a mate has a lightweight 22+lbs bike and a 30+lb bike I can keep up with him when he is on the heavy one but not when he is on the light one when climbing. This difference is about 4-5% of the total all up weight of rider and bike.
All my bikes have to be carried up 106 stairs at the end of each ride so weight is important to me. 25lbs is the ideal weight iIMO – 30+lbs is far too heavy