How to bleed Shimano road hydraulic disc brakes

If your hydraulic disc brakes have started to feel mushy or imprecise, then you need to bleed them.

Clock11:00, Tuesday 27th June 2023

Tools Needed

Tilt the bike down for the front brake, and up for the rear

Step 1

Get the bike ready

If you’re bleeding the front brake, put the bike in a work stand angled slightly down to stop the forks from moving around. When you’re working on the rear brake, angle the bike upwards to help with bubble flow and use a strap or similar to secure the bars. We’ll just concentrate on the front wheel for now though.

You can reset the pads with a flathead screwdriver too

Step 2

Reset the pistons

Remove your front wheel, then reset the pistons by pushing them gently back into the calliper with a pad spacer tool or a big, flat screwdriver. You don’t want to go in too hard and gouge the brake pads as you can easily damage them.

Remove the pin, then slide the pads out

Step 3

Remove the pads

With the pistons reset, remove the brake pads to stop them getting ruined by any spilt fluid. First remove the little clip on the right-hand side and then undo the retaining pin with the flathead screwdriver.

Top Tip

With your pads out it’s a good opportunity to inspect them for wear and see if you need new ones. Fresh pads always make the system easier to set up anyway, so if in doubt, install a new set later.

The bleed block holds the pistons in place during the bleed

Step 4

Insert the bleed block

Insert your bleed block into the calliper to hold the pistons in place. Secure it with the retaining pin that usually holds the brake pads.

Use a rag to protect the hoods from the mineral oil

Step 5

Protect your hands and bike from mineral oil

Peel back the shifter hood. Before you open up the hydraulic system, protect your hands by putting on some gloves, and protect your hoods by placing a rag around the port to catch any spills.

Be careful not to round out the bolt with the tool

Step 6

Open the lever bleed port

Undo the bleed port screw on the top of the shifter body. It’s quite easy to round these out, so ensure to use a good quality, undamaged Allen key. Make sure you keep the bleed port screw somewhere safe.

You'll need an adaptor for Shimano road hydraulic brakes

Step 7

Fit the reservoir

For most Shimano brakes, before you can fit the fluid reservoir, you’ll need to fit a small adaptor. Screw it into the top of the bleed port. Once that’s fitted, take the fluid reservoir from your bleed kit and screw it into the top of the adapter.

Slide the collar over the end of the tube to secure it

Step 8

Attach the syringe

Half-fill the syringe in your bleed kit with the hydraulic mineral fluid, then take the little rubber dust cover off the bleed port on the brake calliper. Push the syringe hose onto it, and lock it into place with the collar.

Use a 7mm spanner to open the bleed port

Step 9

Open the calliper bleed port

Use your 7mm spanner to undo the calliper bleed port a quarter of a turn.

Remove the plunger to let the fluid flow freely

Step 10

Remove the plunger from the reservoir

Before you depress the syringe, remove the stopper from the reservoir.

Slowly push the fluid through the system

Step 11

Push through the mineral oil

Gently depress the syringe to push the fluid through the system. Don’t push too hard as this can cause it to leak. You should see air bubbles coming out of the system and into the reservoir. Continue to push fresh fluid through until the bubbles stop or you only have 10ml or so left in the syringe.

Step 12

Close the calliper bleed port

Tighten the calliper bleed port with the 7mm spanner. Then, pull back slightly on the syringe plunger while removing it to reduce spillage. Clean up any oil with a rag or paper towel – any remaining oil could contaminate the the pads.

Use the syringe to suck any remaining air from the top of the system

Step 13

Suck out any bubbles

Now stick the syringe hose carefully into the fluid reservoir at the lever end and see if you can suck any stubborn bubbles out of the system from the top end. Once you’ve sucked any final bubbles out of the system, remove the syringe, and plug the fluid reservoir with the plug pin.

Top Tip

Tapping the brake hose from the brake end up to the lever end can help detach air bubbles stuck to the sides of the brake or hose and ‘burp’ them up to the top.

Remove the reservoir and close the port

Step 14

Remove the reservoir and replace the bleed port bolt

With the plunger in the reservoir, unscrew it from the bleed port and place it to one side. Then, replace the bleed port bolt. Clean up any spilt fluid, then fold the hood back into place.

Slide in the pads, and secure with the retaining pin

Step 15

Refit the pads

Remove the piston spacer and refit the pads. Slide them into place and screw in the retaining pin. Make sure to put the safety clip on the end of the retaining pin.

Attach the front wheel

Step 16

Install the front wheel

Attach the front wheel to the bike. If you don't have a thru-axle, it's wise to put the bike on the ground to make sure the wheel is centred in the dropouts.

Tighten the bolts as you pull the brake

Step 17

Centre the callipers

Loosen the calliper bolts slightly, just so the calliper can move around on the frame. Then, pull the brake, and tighen the calliper bolts as you hold the brake closed. This should centre the calliper around the disc.

Related Content

Link to How to prevent numb hands when cycling
YouTube video Izc-t0axYzI

How to prevent numb hands when cycling

If you’ve ever felt your hands go numb while riding your bike, follow these simple tips to prevent it from happening

Link to Quick but brutal 15-minute HIIT indoor cycling workout
YouTube video MM6TnN5qvvE

Quick but brutal 15-minute HIIT indoor cycling workout

A short, tough sprint session that is easy to squeeze in for time-strapped cyclists

Link to Sweet spot endurance training: 30-minute indoor cycling workout
YouTube video V-HmspieYjE

Sweet spot endurance training: 30-minute indoor cycling workout

Manon Lloyd leads the way in this half-hour HIIT workout, designed to work the sweet spot training zone with some sprint intervals included at the end

Link to Indoor training 20-min recovery ride with Hank
YouTube video wjAYieMdQbQ

Indoor training 20-min recovery ride with Hank

This easier session is a great way to ease into training, or recover from a hard session. Follow Hank's lead for a progressive recovery ride

Subscribe to the GCN Newsletter

Get the latest, most entertaining and best informed news, reviews, challenges, insights, analysis, competitions and offers - straight to your inbox