It's the bike. In the right human powered vehicle even you or I could out do a time traveling Eddie Merckx from 1972 with his traditional bike.

The HPV hour record is 82% faster than the UCI record. For Ondrej Sosenka to close that huge gulf he'd need about 6X the power which is nearly triple the difference between a cat-4 pack filler (about 3.2W/kg) and Lance Armstrong at his peak (6.75 W/kg). To match Boardman he'd still need about 40% more power.

Eschewing the UCI's restrictions entirely the HPV hour record is 90.6 km or about 56.3 miles in one hour.

UCI's best human effort is a mere 62% of that with Boardman covering just 56.4 km or 35.0 miles in one hour.

The official UCI hour record on a drop bar bike is only 49.7 km or 30.9 miles.