Adrian Van Anz’s vision of a commuter bike that embodied elegant and classic design came to fruition when he started up Derringer Cycles – named after the pocket size old pistol. His bikes fuse classic motorcyle design with a standard bicycle. There are some old-fashioned details such as the leather bicycle seat that play up the vintage appeal. The bike features a 4-stroke Honda engine and can achieve speeds up to 40 mph (see specifications after jump). Placed orders take up to a month, and the cost tops $3,000 US for many of their models.
Continue reading for additional images and specs.
TECHNICAL SPECIFICATIONS
Engine
[BAMF-II Model] Honda built overhead valve 4-stroke engine displacing 49cc, CARB and EURO 2 emission compliance, up to 180 mpg depending on usage. EZ-Start Recoil
Brakes
70mm drum front brake, coaster style rear brake.
Capacity
Fuel Tank: 1.8 US Gallon, 87 Octane 
Engine Oil: .26 US Quart
Performance
Top speed for off-road only models can exceed 35 mph. Derringers designated for road use are modified so as not to exceed the power and speed limitations imposed on motorized bicycles by the laws of the region in which they will operate. This can vary from 20 mph to 40mph depending on city, state, or country.
You should check out imperial cycles they design and build comparable bikes with a more custom feel to them at half the cost. Plus they design and build there own frames and they had there own tanks done.
Check them out at:
http://www.imperialcycles.blogspot.com