Finally, the correct screwdriver for adjusting the screws on Shimano derailleurs.

I can't be the only home mechanic who's wondered why adjusting the stop screws on Shimano rear derailleurs is such a fiddle. I came across the answer recently browsing bike websites and have finally got the answer. Shimano are a Japanese company and, despite probably exporting 90% of their products outside of Japan, have used Japanese standard screws.

 

In this case the standard is JIS (standing for Japanese Industrial Standard, funnily enough) and the size is +2. This is a trick owners of Japanese motorbikes have been aware of for years although it seems to be taking longer for the cycling community to catch on. Anyhow, I found this screwdriver on Amazon, although a quick Google suggests it's available from many different vendors now, and I can confirm it fits the derailleur screws perfectly!