How to shorten a MTB brake hose?
Beyond the aesthetic operation, adjusting your Road or MTB brake hoses allows good braking efficiency. Behind this simple cut are some manipulations aiming at purging the system of possible air bubbles.
Required tools
Spanners 2.5 and 4 mm / Wrench 8 mm / Cutter / Pliers / Mallet / Hose bit / Shimano mineral fluid / Shimano bleeding funnel (if not available, we will use a syringe without piston).
1/ Dismounting
Remove the rubber nut cover and then, using the 8 mm spanner, loosen the connection nut fully and pull back to remove the assembly.
2/ Cut
Hold the hose in place with the bit and clamp (you can also remove the brake from the bike and place the bit in a vice for comfort). Cut to the desired length.
5/Remounting
While holding the hose to the bottom of the master cylinder, tighten the connecting nut fully. (Some threads should remain visible, as they were originally.)
6/ Lever orientation
To eliminate any air bubbles, turn the lever to the horizontal position.
7/ Bleed screw
Using the 2.5 mm Allen key, loosen and remove the bleed screw and O-ring.
8/ Funnel
Install the purge funnel or, alternatively, a syringe without a plunger to extend the system and allow air to rise freely.
9/ Add oil
If liquid has escaped when opening or cutting, air will be trapped. Pour some liquid into the funnel to purge the system.
10/ Bleed
The MTB Brake is new, it is therefore not necessary to open the system at the caliper. Operate the lever fully to see the air bubbles rise to the surface.
11/ 45° bleeding
Then repeat the operation by tilting the lever 45° upwards and then downwards until the last bubble is removed (tip: tapping along the hose can speed up the process).
12/ Dismantling of the funnel
Return the lever to the horizontal position and close the vent in order to remove the funnel without the liquid spilling out.
13/ Tightening
Taking care not to damage the seal, replace the bleed screw, tightening it to the recommended torque using a torque spanner.
