Average time to ride a bicycle 12 miles at moderate speed?

10 mph is quite often quoted as the average ride speed of a cyclist.

so 12/10 = 1.2.

1.2 in hours is one hour 12 minutes, assuming you're able to keep going all the time.

Answer

Just yesterday my neighbor and I did 12 miles and took us 3hours, 10mins. Consider subtracting a 2 mile shift (back and forth to route, 4 miles), so it's around 2 hours at a normal mountain bike & a cruiser. We went trough a lot of residential areas and mixd with some highways; very inconsistent route may I say. So anything under 2 hours is your bet.