Shimano brakes are some of the best out there but they still need regular maintenance. The brakes use mineral oil, which isn’t hygroscopic like the Dot fluid used by many other brands, so Shimano recommends replacing the fluid in its brakes when it becomes discoloured, rather than on a purely annual basis.
You can dismantle the brake to check the colour but there are some obvious signs all is not well — if your brake levers have a longer throw than normal or they have spongy or inconsistent feel. You should also go through this process if you’ve had a leak, need to replace a damaged hose or have made a mess of shortening one.
In addition to regular tools you’ll need an SM-DISC bleed tool (£4), a 7mm ring spanner and a Shimano bleed kit (839 980 – £9.99), which consists of some mineral oil and some plastic tubing.
Waste oil can be caught in a plastic bag taped onto some additional tubing, but you can easily make a better device with an old drinks bottle.
Need to know
30min per brake
Tools for the job
Shimano Mineral Oil, SM-DISC Bleeding Tool, tubing and receptacle for old fluid, bleed block, syringe, 7mm ring spanner
Around £25 per end
Got into trouble?
If things don’t work right you can always repeat the bleed process. Use your friendly local bike mechanic as a last resort.
Mineral oil isn’t half as evil as Dot fluid, but gloves and eye protection are strongly recommended