I talked to Sam Whittingham briefly after his speed record fell last September. 133.78 km/h beat his old record by 0.6 km/h. I think his record stood for about 13 years. He says now it all comes down to the tires, they are the one component that takes major money to custom make. Nobody makes tires for 133km/h bicycles. As long as everybody is using the same tires, nobody is going to go significantly faster. Hopefully they've found a source for high speed tires.