I think tires and riding position make a much bigger difference than bike weight.
On the same route my upright running 35s takes 44 minutes usually. The road bike running 23s, usually 37 minutes. I don't think for a minute that there's that much difference due to weight. I guess I could just strap on about 15 pounds of weight to the road bike to find out.
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Work: the 8 hours that separates bike rides.