Shimano rotors are slightly thinner than Magura models. Their thinness puts them at the limit allowed by Magura.
Combining Shimano rotors with Magura brakes is technically not a sound decision if one wants the entire system to agree with the official documentation.
That said, some people have successfully used Shimano rotors with Magura brakes without noticing a difference.
Others, however, say that the brakes feel a bit different when coupled with Shimano rotors.
If you want to get the most out of the brakes, it’s wiser to combine them with the rotors recommended by the manufacturer.
Differences Between Shimano and Magura Rotors
The main difference between Shimano and Magura rotors is their thickness.
Below is a table containing the thickness of popular Shimano and Magura rotors.
|Shimano SM-RT86||1.8mm||Magura Storm HC||2.0mm|
|Shimano SM-RT10||1.8mm||Magura MDR-P||2.0mm|
|Shimano SM-RT56||1.8mm||Magura Storm SL.2||2.0mm|
|Shimano SM-RT70||1.8mm||Magura MDR-C||2.0mm|
Conclusion: Shimano’s rotors are 0.2mm thinner than Magura’s models. The difference is not as small as it sounds.
Some Magura rotors (e.g., Magura Storm SL.2) have a text on them indicating that the wear limit of the rotor is 1.8mm.
Or in other words, the default thickness of Shimano rotors is the lower limit of Magura’s rotors.
This could explain why some users say that Shimano rotors coupled with Magura brakes don’t offer solid performance.
The Consequences of Using Thinner Rotors
Relying on thinner rotors than what the brakes are designed for has the following downsides:
- Worse Modulation
Modulation is a term describing the control that the rider has over the braking force. If a brake has little modulation, the pads will lock or release the wheel too quickly. If a brake has too much modulation, the brake lever will bottom out before the wheel is locked.
Thus, in the perfect scenario, the modulation will be somewhere in the middle.
Rotors that are thinner than what the brakes are designed for hurt modulation because the pads have a longer travel. As a result, the brake lever also has to move more to make the pads grab the rotor. The result is “dead space” and loss of modulation. The feeling will be similar to using worn pads.
- Voided Warranty
By combining the brakes with rotors that they aren’t officially designed for, one may void the warranty of the brakes.
Additional Requirements For Rotor Compatibility
While it will be wiser to stick with the rotors recommended by the manufacturer, Shimano rotors can still work to a satisfying level.
That said, there are additional compatibility requirements, such as:
The diameter of the rotor should be compatible with the brake model. If the rotor is too large, it will rub against the upper part of the caliper.
The diameter of the supported rotor is dependent on the mounts, the brake calipers, and the presence/absence of adapters.
If you want to install a larger rotor on a system designed for a smaller one, you will need an adapter to increase the distance between the caliper mounting points and the caliper itself.
The three types of disc brake mounts are – International Standard, Post Mount, and Flat Mount
International Standard (IS) is found on older forks and frames. The brake caliper attaches via bolts screwing perpendicularly to the mount.
If you have IS mounts and want to switch from 160mm to 180mm rotors, you will need a +20 IS to Post Mount adapter.
Post Mount (PM) is found on modern bikes. The caliper attaches via bolts going straight into the mount.
If you have PMs designed to run 160mm rotors by default and want to upgrade to 180mm, you will need a 20mm post mount adapter.
Flat Mount (FM) is a fairly new disc mount standard found on road bikes. The caliper attaches to a flat part of the fork or frame. The goal is weight saving and simplicity. Flat mounts are limited to 160mm rotors.
Note: If you have Magura brakes and want to learn more about the adapters that you may need, you can find the official documentation here.
Summary: What You Need To Know
- Shimano rotors can technically work with Magura brakes but are not optimal for the task because they’re 0.2mm thinner than the models recommended by the manufacturer.
- The wear limit of Magura disc rotors is 1.8mm which is the default thickness of Shimano rotors. Thus, in a sense, Shimano rotors are already worn out from the perspective of Magura brakes.
- Thin rotors result in reduced braking modulation (control over the braking force).
- Some people have used Shimano rotors on Magura brakes without noticing degradation in braking. Others, however, say that the brakes just don’t feel as solid.
- For optimal results, it’s recommended to use original rotors.