I held back sending my 2 x cheapo Aldi computers back and found an interesting post on BR that part answered the KMH and lack of wheel size input for MPH. Also from my testing.... 1. Completely ignore the MPH Wheel Size table - only input the value for KMH. 2. You can use MPH - just switch to it from the ODO screen - press and hold set for 2/3 seconds then change to MPH after the language and then click SET. 3. Small wheel sizes - e.g. kids bikes. The minimum number you can input is 1945 which is about 24". There is a trick though. For a smaller wheel, eg. 20" the value is 1590. Input it as 2590 first, save the settings. Goto the ODO screen, hold set for 2-3 seconds go through Language (press M1) then MPH/KMH (Press M1) then on the Wheel Size, press M2 to change the two to a one - do not press M1 (this will then default the next number to 9 - so 1900 is the minimum now). After changing to a 1, just press set. - the wheel size will be 1590 and suitable for 20". Works a treat. So completely ignore the MPH wheel sizes - the size is input as the KMH and then when changed to MPH it is automatically adjusted for - blooming stupid instructions. There were loads left in my local Aldi the other night.