Condensed Answer: SRAM rotors can be used with a Magura brake as long as they’re of the right diameter. However, SRAM rotors are 1.85mm thick whereas original Magura rotors are 2.0mm and have a wear limit of 1.8mm.
Or in other words, SRAM rotors start very close to the minimum thickness that Magura brakes are designed for. To preserve the original modulation of the brakes for as long as possible, it’s recommended to stick with the supplied Magura rotors.
Compatibility Requirements
A rotor has to meet the following criteria to operate with a set of brakes:
1. Size
Before all, the diameter of the new rotor should be compatible with the brakes.
SRAM and Magura rotors are available in the following sizes – 160mm, 180mm, 203mm, 220mm.
The new rotors should match the size of the original ones. To learn what size rotors your brakes need, you can go to the product description, search for the recommended rotors and look at their sizes.
If you purchase a rotor that’s too large for a particular set of calipers, you won’t be able to install the wheel because the rotor will push against the caliper.
That said, it’s possible to switch to bigger rotors by using an adapter.
The main function of adapters is to increase the distance between the brake mount and the caliper.
The adapter that you will need depends on the original mounts of the frame and fork. There are three main disc brake mounts – International Standard, Post Mount, and Flat Mount
You will find IS mounts on older bikes whereas PM are common for newer models.
Flat mounts are a new standard used for road bikes. This mount is limited to 160mm rotors.
2. Thickness
Ideally, the thickness of the replacement rotor will match that of the original one.
In this case, this doesn’t happen because SRAM’s rotors are 1.85mm thick whereas Magura’s are 2.00mm.
Also, some Magura rotors have a marking on them indicating a wear limit of 1.8mm. In other words, the rotors should be replaced when their thickness has fallen to 1.8mm.
Thus, it won’t take long before a SRAM rotor is at the limit specified by the brake’s manufacturer.
FAQ: What are the dangers of using thin rotors on brakes designed for thicker ones?
Thinner rotors increase the distance that the brake pads have to travel to grab the rotor. As a result, the rider has to press the lever harder to initiate braking. The effect is similar to using a brake with worn pads.
This outcome can be mitigated to a degree by pushing the pads closer to the rotor via the available settings on the caliper. However, this adjustment reduces the modulation of the brakes.
In conclusion
Due to the notable difference in thickness, it’s recommended to stick with the recommended rotors so that the brakes perform as intended.
Nonetheless, people have successfully used SRAM rotors with Magura brakes, and it won’t be accurate to conclude that the dissimilar thickness is a total deal breaker.
3. Hub Compatibility
The attachment system that the rotors use should also be compatible with the hub on which they have to be installed.
There are two main options – center lock and 6-bolt.
Center lock hubs rely on a Shimano patented technology. The rotor is mounted and secured to the hub via a lock ring similar to that of a cassette.
If you have bolt-on hubs, you will need a bolt-on rotor.
If you have a center lock hub, you have two options:
- Install center lock rotors
- Install bolt-on rotors by using an adaptor
Brake Pad Overhang
When using rotors that aren’t originally designed for the brakes, a phenomenon known as brake pad overhang might take place.
If the new rotors have a brake track narrower than the original, a small section of the pads will remain untouched and will therefore “hang”.
Subsequently, that section will never get thinner due to the absence of friction while the remaining body slims down.
As the pads get smaller, there will be a point when the non-damaged sections of the pads touch each other and effectively prevent the pads from grabbing the rotor. When that happens, the brakes will fail to do their job.
Normally, this problem doesn’t occur when the new rotors match the size of the old ones. For 100% certainty, however, it’s recommended to examine the brakes and make sure that the pads are in full contact with the rotors.
If that’s the case, the rotors are not appropriately shaped for the particular system and have to be replaced.
Note: Sometimes brake pad overhang occurs because the brakes use an adapter that’s too large for the rotors in question.
Summary: What You Need To Know
SRAM rotors can operate with Magura brakes when the following criteria are met:
- The rotors should be the right size for the brakes. The user can upgrade to larger rotors by using an adapter. The needed adapter depends on the disc brake mount and the size of the new rotors.
- SRAM rotors are notably thinner than original Magura rotors but not thin enough to completely disqualify them. For optimal performance, however, it’s recommended to use rotors approved by the brake manufacturer.
- The new rotors should be compatible with the hubs. The two main attachment methods are 6-bolt and center lock.
