This is a very clean looking speedometer. Will fit 1977 R100RS and R100S only. The ratio is 1.078 which is a 32/11 rear drive ratio. This number is stamped on the drive where it bolts to the swingarm. The needle moves back and forth smoothly. When I was testing it I got two miles on the trip meter and odometer also recorded two miles. I tried to put a third mile on it and quit moving. The face is in immaculate condition. This would perfect to install when your speedo is getting rebuilt or if your is damaged and need to ride the bike. This would also be a great core. This is NOT returnable. I have the matching tach. I have a lot of BMW instruments and parts. Contact me with any questions you may have. I run a BMW motorcycle salvage yard.