Bike computers - more bang for your buck

Yesterday I went to Halfords and purchased their 5 function bike computer (item code 679286). This seems to be a common model. You can buy them on eBay and Amazon too but with different names on them.

Unpacked it all, and boy you sure do get more bang for your buck You get the bike computer itself and the cradle it sits in. Cable ties for attaching the cradle to the bicycle handlebars, cable ties for attaching the magnet sensor to the the bicycle front wheel fork, and the magnet and screw attachment for attaching to bicycle spokes and the instruction manual. The manual  is a double sided A4 page but gives enough detail to cover all aspects for fitting to a bicycle. There is a wheel size chart that allows conversion from wheel size to setting value. The chart lists the smallest wheel size diameter as 305mm. However, I see from the manual you can also use a calculation to determine the setting value, so in theory smaller wheels (90mm diameter) such as those on my longboard should still be possible - the only thing in the back of my mind is that the bike computer might have a limitation to smaller wheels. This is because the magnet on a smaller diameter wheel would pass the sensor at a higher rate than for a bigger wheel and the bike computer may not be able to keep up. The only way to find out is to experiment!