My new commuter is no lightweight... lets say keep it away from most big hills.
Dry the bike weighs in around 33 pounds... add rack, pedals, lighting (HID) bag, clothing, bike tools, lock, etc and it blossems to 44.5 pounds... I go a good laugh at the bike shop when I brought it in and weighed it. The thing rides really nice when I am fresh, about mile 9 - 10 it starts bogging on you, just say it is a 5 - 15 mile commutter and errand runner.
In contrast my road bike weighs in a 17.9 pounds (63 cm) and the TT bike in at 19.6 pounds... featherweights in comparison. The commutter gives me a good quad workout for sure!
That got me thinking... what is the heaviest bike that YOU have ridden... not seen but ridden.
For me it was a motorized patrol bike, weighing in at over 65 pounds with batteries... that sucked going up hills and even cornering!