How to replace the rear brake in an Amflow PX

[GVA Rider]

Tell me what steps to take to remove the rear brake and replace it in a 2026 Amflow PX

 

[RickBullotta]

Tell me what steps to take to remove the rear brake and replace it in a 2026 Amflow PX

Totally depends on what you're replacing it with! You may be able to reuse the brake hose in some cases.

 

[Greg Watts]

Tell me what steps to take to remove the rear brake and replace it in a 2026 Amflow PX

@GVA Rider - the 2026 Amflow PX Carbon ships with

Magura Gustav Pro hydraulic disc brakes, 4-piston caliper, 203mm rotors front and rear.

Magura uses mineral oil (LLK).

General steps for a rear brake caliper swap on the PX:

• Shift the rear wheel out of the way if needed for access

• Remove the caliper from the IS/post-mount adaptor (typically 2× T25 bolts) - keep the adaptor unless your replacement needs a different one

• Disconnect the hose at the caliper end - have a rag ready, mineral oil will drip

• If reusing the hose: fit a new olive and barb, thread into the new caliper, bleed per the new brake's procedure

• If fitting a complete new brake with its own hose: route it through the frame (the PX has internal routing) and connect at the lever end too

• Reinstall caliper on adaptor, align to rotor with wheel in place - loosen bolts slightly, squeeze lever, torque to spec

• Bed in pads with 20 - 30 firm stops from ~20 km/h before trusting it on trail

Key point: the PX uses internal cable/hose routing, so threading a new hose through the frame takes patience.

A magnetic brake hose guide tool makes it considerably less miserable.

What are you replacing it with?

That'll determine whether the adaptor, hose, and fluid type carry over.

 

[RickBullotta]

@GVA Rider - the 2026 Amflow PX Carbon ships with

Magura Gustav Pro hydraulic disc brakes, 4-piston caliper, 203mm rotors front and rear.

Magura uses mineral oil (LLK).

General steps for a rear brake caliper swap on the PX:

• Shift the rear wheel out of the way if needed for access

• Remove the caliper from the IS/post-mount adaptor (typically 2× T25 bolts) - keep the adaptor unless your replacement needs a different one

• Disconnect the hose at the caliper end - have a rag ready, mineral oil will drip

• If reusing the hose: fit a new olive and barb, thread into the new caliper, bleed per the new brake's procedure

• If fitting a complete new brake with its own hose: route it through the frame (the PX has internal routing) and connect at the lever end too

• Reinstall caliper on adaptor, align to rotor with wheel in place - loosen bolts slightly, squeeze lever, torque to spec

• Bed in pads with 20 - 30 firm stops from ~20 km/h before trusting it on trail

Key point: the PX uses internal cable/hose routing, so threading a new hose through the frame takes patience.

A magnetic brake hose guide tool makes it considerably less miserable.

What are you replacing it with?

That'll determine whether the adaptor, hose, and fluid type carry over.

You skipped quite a few steps - on an eMTB it is often necessary to loosen cable guides, drop the motor, etc...

 

[Greg Watts]

You skipped quite a few steps - on an eMTB it is often necessary to loosen cable guides, drop the motor, etc...

@RickBullotta - fair point, and a good one.

I kept it at a general level and glossed over some eMTB-specific steps.

To flesh it out properly for the PX:

Steps I should have included:

•

Cable/hose management first - before anything else, photograph the existing hose routing.

The PX has fully internal routing and the rear brake hose runs through the frame.

•

Motor access - on many eMTBs with internal routing, the hose path runs close enough to the motor bay that dropping the motor (or at minimum loosening it for clearance) makes threading a new hose considerably easier.

I'd caveat that I can't confirm the exact routing path on the PX specifically without checking the service manual - if you have firsthand experience of that job on this chassis, worth chipping in.

•

Cable guide clips - internal hose guides, retention clips, or grommets often need releasing to free the old hose.

These are easy to crack or lose; have spares.

•

Hose threading tool - on a full-carbon internally-routed frame, a magnetic guide is essentially mandatory rather than "nice to have".

•

Sealing grommets - reseal any frame entry/exit points properly when done.

Good catch - eMTB internals do add steps.