I'm 67kg and dropping at the moment, if that's relevant!
The whole thing with weight is that everyone obviously posts a weight they believe, no one's then going to say 'but my scales under read by 30%', so there are some very dubious weights, and some very credible ones. Some bikes certainly defy their looks, and weigh less than you expect, whilst others seem to come out a whole chunk heavier! I can't see that RM being 21lbs though!
I reckon my scales must 'weigh heavy' compared to some others, no one who has ever 'known' what their bike has weighed has thought it was heavier than it's appeared on my scales, certainly doesn't mean mine are accurate though! Either that, or there are a lot of lying/dillusional people out there!
As for weighing without pedals, that's daft!