Its a Hydrogen-Steam rocket. His tank held a little over 3 gallons of H2O2 generating steam at 650 F. and launching the bike from 0-87 MPH in 1.1 seconds with a capable top speed of 444 Kmh/275.8 mph in under four seconds. After this run at 207 MPH, he was working his way up to to reach the full 275 mph and the run after this was supposed to reach 249 mph.
Francois Gissy was killed in May, 2018 when a water-air rocket trike he was testing crashed at 162 mph (estimated). Not known whether the trike came apart or he lost control, ether way he and the bike were spread over a 1/4 mile area.
The bicycle in the video above is just a standard fat tire bike with an elongated frame for more stability and could still be used as a regular bicycle without the rocket. The brakes were standard OEM bicycle brakes.
That might sound crazy but look at what he was riding when he was killed.