Centerlock vs 6 Bolt: What Brake Disc is Better?
Brake disc assembly – you only have to tighten six screws and you’re done, right? Not quite, in fact there is a lot more to consider, from the selection of the type of brake disc, to suitable adapters, assembly, tightening torques and much more. So that you never make mistakes with this safety-relevant component, we have summarized the most important difference of Centerlock and 6 Bolt standards.
Centerlock vs 6 Bolt
Basically, there are currently two different fastening standards: Centerlock and 6 Bolt. In the latter standard – as the name suggests – the brake discs are attached using six screws. Depending on the manufacturer, these should be tightened with 4-6 Nm (observe both the manual for the hub and the disc). There is a lock on the screws so that the brake disc cannot come loose.
Centerlock, on the other hand, manages with a single hole that is assembled using the same tool that is required to assemble a cassette or bottom bracket. A good 40-50 Nm of torque are required here. A toothing on the hub and on the end ring prevents the brake disc from loosening. So, just like with 6 Bolt, the system is absolutely safe and reliable.
The advantages of Centerlock are that it is easier to install. Since only one hole has to be tightened here, it is much faster and more relaxed. Of course, this only applies if you have the right tool. Depending on which hubs and discs are used, a slight weight advantage over 6 Bolt systems can sometimes be achieved. However, this point is difficult to generalize. A major disadvantage of Centerlock is the reduced selection of components. The standard originally comes from Shimano and so mainly the Japanese offer matching discs. Even with the hubs, not every component manufacturer has jumped on the Centerlock train.
So if you want maximum selection, you’d better use 6 Bolt. They are also basically superior on alpine crossings or other longer tours, since they can be dismantled with most multitools (usually a T25-Torx is required). For Centerlock, you would have to carry a bulky cassette tool. In an emergency, a screw for 6 Boltis also significantly lighter than the locking ring of a centerlock system. So if you like to be a little off the beaten track, 6 Bolt is better for you. A disadvantage, on the other hand, is that incorrect tightening can cause the pane to become distorted and lead to defects. In addition, one or the other has already broken one of the six threads in the hub. So be careful here.
|Advantages||Easy and quick assembly||Large selection of hubs and brake discs|
|Possible weight advantage||Assembly using a multitool (usually Torx-25)|
|6-hole brake discs also possible with adapter||Easy to get replacement screws|
|Compatible with 15 / 20mm axles|
|Disadvantages||Special tool necessary||Assembly takes longer|
|Reduced selection of brake discs and hubs||More likely to damage a thread|
|Different end rings are required for different axes||No conversion to Centerlock possible|
Installation of the brake disc
Regardless of whether it is a 6 Bolt or Centerlock – it is extremely important to always look at the mounting direction of the disc. Most brake discs have a running direction in which full stability can be guaranteed.
The reason is as follows: When the brake disc is installed the right way round, the spokes of the disc (or the spider) are subjected to pressure, i.e. they are compressed. The friction ring, on the other hand, is loaded under tension. If the disc is mounted upside down, the reverse occurs: spokes on tension, friction ring on pressure. This has fatal consequences when the brake disc gets hot. Now the resistance of the steel is decreasing, which is why the friction ring can collapse under pressure. You can imagine it like this: If you take a wire rope in your hand, you can pull it and it is perfectly stable. However, if you press it together, it does not take a stable shape and collapses. It is therefore absolutely safety-relevant to mount the brake disc in the direction of rotation.
With 6 Bolt, you should also make sure that the individual screws are always tightened crosswise during assembly. This prevents tensioning of the disc, which could also have a negative effect on its stability. The above-mentioned torques should of course always be observed, which also applies to Centerlock discs.
In addition, you should always work on the brake with clean fingers, otherwise you can first contaminate the brake disc and then the brake pads. Of course, oils and fats in particular are problematic here.