Message from Hugh Jones
Dear Tom and Pete.
Born April 2008, died on 11 March 2013. The counter you gave me to wear-test to destruction nearly six years ago failed on a measurement two days ago. The mode of failure was the rotating disc being ground down over the years so that rotation became asymetric. The cogs started to catch and that generated resistance, which in turn deformed the tang. I had this on my bike almost all the time for those six years so it covered a lot of distance (thousands of miles).
I hope that the next one I use will be as hard-wearing, but I will now only mount it on the bike on those days when I am actually measuring.