Welcome back to Threaded! Since I’ve already covered my favourite hex and Torx tools, I figured I’d keep the theme of fastening turning with some thoughts about screwdrivers.
Sure, flat-head and cross-head fasteners aren’t nearly as common on bicycles as they once were, but if you own a bike from a few years ago, or one that came at a more affordable price point, then there’s a high chance you have at least a few cross-head screws to contend with. And if you’re working in a shop, they're still an every-damn-day thing.
This article is mostly about such screws. More importantly, I wanted to further spread the word that JIS is effectively a modern-day myth. What the hell is JIS? And how the hell dare I?! This and more in this edition of Threaded.
Phillips vs JIS
Compared to the common slotted (aka flat-head) screw before it, the now ubiquitous Phillips screw head came about in the 1930s with its recessed self-aligning design aimed to speed up assembly lines and reduce human error. Unfortunately, that same self-aligning element means the tool comes out of the screw just as easily, or in other words, it doesn’t take much torque for it to cam-out. This easy cam-out is thought by many to be a purposeful torque-limiting feature, but history suggests it was an unintentional limitation and only later used as a selling point.
Whether done to skirt the Phillips patent or improve the design, the Japanese Industrial Standard (JIS) came about in the 1950s. With a more squared geometry and blunter tip, the JIS cross-head screw allowed for more torque without any notable disadvantage. And in the ensuing decades, most cross-head fasteners on Japanese-made products were JIS. With JIS fasteners looking almost identical to a Phillips, some, but not all, offer a small dot or cross next to the recessed cross-head as an identifier.
Using a traditional Phillips screwdriver in a JIS screw will lead to a sloppy fit and easy cam-out. This is largely because the sharp end of the tool prevents the vertical slots from sitting in the fastener fully. If you’ve ever made a mess of older Shimano limit screws, you were likely using the wrong drive system. Meanwhile, using a JIS screwdriver in a traditional Phillips head often improves the fit. So JIS is the answer, right? Well, yes, but also not anymore.
It was nearly a decade ago at BikeRadar that I wrongly spread the word that everyone should own a JIS screwdriver. I was right in that a lot of Shimano components from yesteryear had JIS screws, but I was wrong in that you needed a specific JIS screwdriver not to round them. Rather, you need a screwdriver that meets modern international standards for Phillips.
International standards have been in place for over two decades to unify cross-head hand tools. Today, the DIN ISO 8764-1:2006 standard lays out sizing and dimensions for Phillips (and Pozidriv) that are extremely similar to the JIS standard. Basically, if you’re looking for a JIS screwdriver today, then a modern ISO-compliant Phillips (PH) is it. And if your Phillips screwdrivers have a sharp point to them, then the sole mission of this article is to get you using a better tool.
Much like the Wild West of road tubeless, brands aren’t legally required to adhere to the international standard. As a result, a mix of tools in the market will give you varying quality of fitment in a fastener. Most quality tools, at least those from big European or Japanese brands, are now typically made to these new standards. Meanwhile, some American brands are still producing outdated and sharp-pointed Phillips drivers. And just like hex and Torx keys, even brands that meet the standards still have varying security of fitment with fasteners.
And so that leads me to my favourite screwdrivers and the sizes you need …
Trial and error
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