RPM = speed

mrfins99 · Post by **mrfins99** » Sat Jul 15, 2017 4:38 pm

On a CB77 at 5000 rpm, what speed am I going in high (fourth) gear?

G-Man · Post by **G-Man** » Sun Jul 16, 2017 7:53 am

Depends on your gearing and tire size.....

G

DJM · Post by **DJM** » Sun Jul 16, 2017 2:04 pm

As G-Man says it will depend on the sprockets and rear tyre you have fitted.

Early CB77s came standard fitted with a 30 tooth rear sprocket, later ones came with a 32 tooth sprocket, all had 15T gearbox sprockets fitted as standard.

Period Road Tests give include the following figures.

Early CB77, MPH per 1000 rpm = 11.2 so 56MPH at 5000 rpm

Early CB72 (and LATE CB77s) MPH per 1000 rpm = 10.8 so 52 MPH at 5000 rpm

Bear in mind that these figures relate to standard tyres of the time more modern (larger?) tyres will give different speeds as obviously will different size sprocket to those given above.

After fifty years don't bet on your speedo or tacho being better than 90% accurate.