Magura QM 46 Brake Caliper Adapter PM 203 to 220 mm

The Magura QM 46 is a brake caliper adapter that lets a caliper with a Post Mount (PM) 203 mm fitting run a 220 mm brake rotor. It fits mountain bikes (MTB), electric mountain bikes (E-MTB), S-Pedelecs, city bikes and e-moto conversions. Two M6×30 bolts come in the box. The adapter body is machined from hardened alloy.

The bracket raises the caliper position by the exact offset needed. As a result, a Ø 220 mm rotor such as the Magura MDR-P or MDR-C 220 sits correctly in the caliper. You therefore keep your existing calipers. One adapter plus a larger disc is the whole upgrade.

This is not a brake and not a brake rotor. The QM 46 is purely a spacer between the caliper and the frame or fork in the PM standard. Because of that, fitting stays simple and the hydraulic system remains untouched.

Key Benefits

• Fast upgrade – move from a 203 mm to a 220 mm disc with a single adapter.
• OEM accuracy – a genuine Magura part with correct mounting point spacing.
• High rigidity – machined, hardened alloy holds caliper position under braking.
• More braking torque – a 220 mm rotor shortens stopping distance versus a 203 mm disc.
• Better heat dissipation – the larger diameter copes with heat on long descents.
• Finer modulation – greater disc leverage lets you meter braking force more precisely.
• Broad compatibility – suits Magura and other calipers using the PM standard.
• Ready to install – 2× M6×30 bolts included.

Who Is This Adapter For?

The QM 46 suits mountain bikes, E-MTBs, S-Pedelec fast e-bikes up to 45 km/h, city bikes and e-moto conversions. Above all, it is used where a Magura bicycle brake has a PM 203 mm fitting. It pairs directly with the Magura MDR-P 220 and MDR-C 220 rotors.

Most often the QM 46 goes on the front brake. However, the frame or fork specification decides the final position. Therefore check that your fork or frame is certified for a 220 mm rotor before fitting. Riders who need more braking torque on heavier e-bikes or long mountain descents benefit most. It also helps anyone who wants more braking power without replacing existing calipers.

What Is In The Box?

• 1× Magura QM 46 adapter (PM 203 → 220)
• 2× M6×30 bolts

Technical Specifications

Why Choose The Magura QM 46?

This is a genuine Magura part, and Magura has built hydraulic disc brakes in Germany since 1893. Consequently, the mounting distances match Magura caliper geometry without extra shimming or adjustment. The original caliper orientation in the PM standard is also preserved.

The adapter itself does not add braking power. The 220 mm rotor does that, while the QM 46 makes it possible to fit. One adapter costs far less effort than swapping a complete brake system. It is therefore the most direct route from a 203 mm to a 220 mm disc.

Installation Tips

• Confirm that your fork or frame permits a 220 mm rotor.
• Apply medium-strength threadlocker to the M6×30 bolts.
• Tighten to the torque figure (Nm) specified by the manufacturer.
• Centre the caliper over the disc after mounting.
• Carry out the pad bed-in procedure.

Frequently Asked Questions

Does the QM 46 work with IS or 6-bolt hubs?

• The hub interface is separate from this part.
• The QM 46 only addresses the caliper mount in the PM standard.

Will it fit my Magura caliper with a PM 203 mm mount?

• Yes, it is designed for calipers with a PM 203 mm fitting.
• It also suits other calipers built to the PM standard.

Which rotors does it pair with?

• Any Ø 220 mm rotor, such as the Magura MDR-P 220 or MDR-C 220.

Is this adapter suitable for an E-MTB or S-Pedelec?

• Yes, applications include MTB, E-MTB, S-Pedelec up to 45 km/h, city bikes and e-moto conversions.

Do I need new calipers as well?

• No, the existing PM 203 mm calipers stay in place.
• Only the adapter and the larger disc are required.

Are bolts included?

• Yes, 2× M6×30 bolts ship with the adapter.

Front or rear brake?

• The QM 46 is most often fitted to the front brake.
• Your frame or fork specification determines the final position.

Does the adapter increase braking power by itself?

• No, the 220 mm rotor provides the extra torque.
• The adapter simply allows that rotor to be used.

For riders moving up to a 220 mm rotor on a PM 203 mm caliper, the Magura QM 46 is the single component that makes the change. It arrives with its M6×30 bolts, keeps the hydraulic system sealed and holds the caliper steady in machined, hardened alloy.