never wishing to trust the Triumph speedo
i use this http://www.gearingcommander.com/
tacho on mine reads 4500rpm and speedo says 140kph
checked the chart after changing the rear wheel size in the apporiate box law and behold i'm do 120 kph true speed if we can trust the chart
i'm running stock 16 up front with a 42 rear regularly getting 240k's outta a tank befor i hit reserve on a 04 speedy

04 yellow&black Speedmaster+the Money Pit{xj jeep}