Almost all modern bikes (road bikes, mountain bikes, BMX, hybrid bikes) these days are equipped with disc brakes and from time to time you might feel the need to upgrade them to better performance according to your needs and like all brakes, there are always compatibility issues and with disc brakes fairly so, especially when it comes to rotors on disc brakes there are so many options and one wonders if they are all the same does there size and thickness matters or not and so on.
Universal is a very broad term so I will divide it down into further terms so you can quickly find what you are looking for
what is the difference between road and mountain bike rotors
Are road and mountain bike disc brake rotors interchangeable
Are any year any model same size rotors interchangeable
Are bigger rotors interchangeable with smaller ones and vice versa
Does the thickness of the rotors matter
Are rotors directional
These are all the questions that you would probably have on your mind and starting with the simplest question are all bike brake rotors universal the simplest and condensed answer to that question is
All brake rotors are universal and interchangeable depending on factors like their styles (6-bolt or center lock) and depending on their thickness as well they can be made compatible otherwise by doing some changes but only the same size, style, and thickness rotors are interchangeable only and that also includes different brands as well
If we take universal in the meaning that if the same size rotors whether they are from different brands or from the same brand as other parts of the brake then we can say that they are universal and interchangeable with the given conditions that
- if the rotors are the same style (6-bolt or center lock)
- if they are the same size (both are 160mm or 140 or whatever size you are equipped right now)
- the thickness of the rotors is the same (like for example if both rotors are 1.8mm or 2mm thick)
If both the rotors meet these criteria in that case we can say that they are universal and interchangeable no matter what brand they belong to.
This was a short summary of if all the disc brake rotors are universal and interchangeable or not, if you want to read more read along for in-depth answers and a better explanation of all the subjects I have mentioned above
what is the difference between road and mountain bike rotors :
For a long time, there were no differences between the rotors on the road bikes and mountain bikes and they were almost the same and interchangeable with the only difference being the size of each of the cycling types for example most of the mountain bikes and road bikes in past used to have 160mm rotor in front and 140mm rotors in rear but on the heavy-duty bikes like downhill bikes and enduro racing mountain bikes rotors were bigger and thicker but usually, the size of the rotor was the same
but over the years now there have been changes in the rotors for both bikes and manufacturers have started to draw a line between them but the difference is not usually seen in the size but in the pattern for example now when you see the rotors on road bikes those are different in designs (vents) compared to rotors on mountain bikes rotors and they are designed better to distribute heat
this is rather the new trend now but over all the mounting pattern is still the same 6-bolt disc rotors are the most common design of the rotors and this is true for road and mountain bikes although Shimano has taken it a step further and changed the mounting style of disc rotors to center lock system rather than the more used style of center lock system
That brings us to the next question and explanation on a basic level of
Are road and mountain bike disc brake rotors interchangeable :
As I have explained above only the design pattern of rotors has changed over the years for simple reasons one is inclined toward cooling and the other inclined toward more power but other than that all the disc brakes rotors have stayed the same
So under normal circumstances, if the rotors on the road bikes that you use have the same thickness (1.8,1.7 or 1.5 etc) as rotors on mountain bikes and they follow the same mounting pattern (both have a center lock or both have the 6-bolt design) then they are interchangeable regardless of what brand or bike model they were mounted on.
that brings us to the next question which has a similar answer to the above question
Are any year/any model same size rotors interchangeable
yes, any year and any model rotors depending on the same criteria as I have explained above are the same/universal and are interchangeable but the same cannot be said for either pad, adapters, or levers of the disc brakes
Things change very drastically in those aspects and I have written separate articles on all of those things because it would get very confusing very fast if I started comparing everything in this one article.
pads, adapters, and levers may vary in specifications and you might need to find similar replacements for them those are very thorough topics in their own aspects.
Are bigger rotors interchangeable with smaller ones and vice versa :
This is where things become critical and most people make the mistake of thinking that either bigger rotors cannot be placed in the place of smaller rotors or vice versa and some make the mistake that they might not need any upgrades if they are trying this set-up
The short and precise version of the answer as to if bigger rotors are interchangeable with smaller ones and vice versa is that
Smaller or bigger rotors are interchangeable and vice versa is true as well but there are certain criteria for it to work
- can your fork and frame afford bigger rotors
- you may need to change the whole braking setup (eg. adapter, pads)
- do you even need bigger rotors
As you may notice some of these things are done able but there are certain questions that you should either ask yourself or check your bike for those references
The biggest problem that people fail to understand here is can their bikes afford these heavy-duty brakes in the first place, for example, if your bike came with 160mm rotors and suddenly you dont feel like they are performing well and you had like to jump up to 203mm rotors the very first question is can your bike afford it
For example, if you are using run of a mill standard cheap bike or an XC bike that has no need for this much stopping power or anything like that the only thing you would get from mounting these kinds of heavy-duty brakes is that you would destroy your forks and in some cases even damage your bike frame so this is what falls on your understanding of “do you even need this kind of stopping power in the first place”
and the other point is that can you afford to make all the changes that equipping bigger rotors may cost you if as I have explained above you have a bike that you know doesn’t need or can take that kind of heavy-duty stopping power
and if you tick all the boxes and you have a bike that you know can sustain this kind of power then you would need a new adapter if there is a need for example if you are not making drastic changes like jumping from a rotor size of 140mm to 160mm then your old set up should suffice but if you are thinking of making a drastic change in rotors like going from 160mm to 203 mm then you would need a better adaptor (4-piston) and bigger pads
if you are a beginner and you are just not sure how to check if your forks can accept the backlash of a bigger rotor then you should read the manual given with your forks it should be clearly written on there how big of a rotor size is recommended with them.
Does the thickness of the rotors matter /are different thickness rotors interchangeable :
The thickness of the rotors does not matter meaning it doesn’t provide any added value to the braking thickness of the brake rotors varies from manufacturer to manufacturer but it has no advantage or disadvantage in braking power
but its also imperative to understand that even though the thickness of the rotors doesn’t matter it doesn’t make them universal either for example if you replace your original rotor which had a thickness of 1.8mm with a rotor that has the thickness of 1.5mm it will negatively affect the braking power of your bike as the brake calipers may be too far apart and it may exceed the lever pull ratio that can affect braking power
So before you try to interchange different thickness rotors remember that it will negatively affect braking if you replace your rotors with thinner rotors the braking power will reduce and if you replace it with a thicker rotor, the rotor will overheat or bend under too much stress.
Are rotors directional :
This is something that can get confusing for some people as well that if brake rotors are directional or not and the simple answer is that
Rotors are not directional even though there is an arrow some time present on them but they are not directional you can mount them however you like it will not have any negative or positive effects on the brakes but mounting them on either side of the wheel may have negative effects
Usually, almost on all the disc brake rotors arrows are not specified on them but in case they are specified on them even then it doesn’t actually have any effects because everything falls on the calipers position and the pads condition and the pads position on the rotors which can ofcourse effect the rotors but direction doesn’t matter as long as you are not trying to mount them on opposite side of the wheel in which case they might interfere with other parts of the bikes