Originally Posted by rpenmanparker

No you are the one who is wrong. The difference due to bike weight is always there. It is difference due to other factors which may come and go as those conditions change. For any set of instantaneous conditions, any energy level of the rider, any wind velocity and direction, any humidity and temperature, any anything, the lighter bike will be faster than the heavier. All those conditions may hide that fact from you, because their effects are hard to quantify, but physical laws are physical laws. Everything equal doesn't mean the conditions are always the same. It means if they were the same when you were riding either weight bike. Can't make that happen in real life? Doesn't matter. Physical laws don't allow for any doubt. Just like others you are stuck confusing something being true with your being able to observe it. There is no validity to that.