Squealing brakes, or brakes that drag, can be one of the most annoying problems with your bike.
Sometimes, the issue can be due to setup, but if you've already followed a disc brake setup guide with no success, then often it’s because of misaligned disc brake calipers.
If you’re setting up your brake calipers and find that each time you tighten the bolt, it pulls the caliper around from where you want it, it's likely because your disc mount needs facing.
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Or perhaps you get it lined up perfectly, but when you tighten the bolts fully, the top or bottom of the brake pad begins to contact the disc – another sign that your disc mounts need facing.
What are your options?
You can take your frame or fork to a bike shop and pay for the privilege of having it faced by the pros. Unfortunately, though, some bike shops may not have a disc-mount facing tool, and often they'll be too busy to fit your bike in.
That's where the home mechanic's dream comes in – the Park Tool DT-5.2. It’s touted as a high-quality, sturdy disc brake mount facing tool to face post-mount, IS mount, and the newest bicycle mount standard: road bike flat-mount calipers.
The DT-5.2 comes in a compact and robust-feeling carry case to pack it down when not in use.
What’s the DT-5.2 like to use?
The versatility initially made me apprehensive. However, I needn’t have worried – the team at Park Tool know a thing or two about building specific bicycle tools, as they've been doing since 1962. Park Tool has a reputation for quality and supplies workshop-grade tools to home mechanics and bike shops across the world.
Upon opening the case, you are confronted with an array of carefully machined and anodised parts.
Thankfully, there are some excellent instructional videos online to show you exactly how to assemble them depending on your bike’s disc caliper mounts.
Once assembled, it becomes clear why the price tag on the DT5.2 is £499.99 / $549.95. This is a quality piece of kit.
It's easy to set up the facing tool in place, thanks to some simple yet effective black alignment studs, which plug into the threaded holes. Use these to align the tool with your mount, snug the bolts up, and the DT5.2 makes a substantial and robust base to perform facing from.
The cutting tool is light to turn and uses a sophisticated-looking but easy-to-use gear drive mechanism.
The tool itself is hardened steel and as sharp as can be; it looks as though it could make mincemeat of any leftover paint from the production process.
It’s often necessary to remove a small amount of material from the frame too, beyond the paint, to get a perfectly flat and aligned pair of mating points for the two disc caliper bolt holes.
The aim is to remove the minimum amount of material possible, but enough so that the mounting point is flat and level.
However, Park warns that although the cutting tool is perfect for aluminium or steel, materials such as carbon and titanium can dull the cutter at a much faster rate than steel or aluminium.
Thankfully, though, Park sells an alternative Diamond Abrasive Adapter cutting tool (part number 2197) if you plan on facing carbon or titanium frames.
Is it my job?
Bikes and forks should come from the factory with properly faced head tubes, bottom bracket shells and disc caliper mounts. However, many still do not. This is because it’s expensive and skilled work to perform facing (and reaming for that matter) properly, so some brands don’t bother.
It would be great to see the industry and consumers take a harder line on manufacturing standards such as this. But, until that time, if you want a perfectly perpendicular perch for your disc mounts, a disc-mount facing tool such as this one is a great investment.
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