Will MTB discs work on road bike
Discussion
I’ve just fitted a pair of Hunt wheels on the Racelight. The wheels are either 6 bolt or centre lock compatible so I’m looking at the centre lock disc options which seem to be limited and certainly expensive when you search road specific.
Is there and reason provided I get the right diameter that I can’t put something like a Deore or XT disc on. Presumably if it will stop a mountain bike it will do the same for a road one.
Is there and reason provided I get the right diameter that I can’t put something like a Deore or XT disc on. Presumably if it will stop a mountain bike it will do the same for a road one.
As long as the dimensions are the same, they will both work. The differences will be slight, and be to do with how the discs last / behave under the different conditions they are designed to be optimal for. Road discs will be manufactured to take more extended punishment than the MTB discs, which will be manufactured with a more ‘short sharp shock’ type of usage in mind, rather than extended period / intensity use for the road specific discs. It’s mainly achieved with coatings, and the types of tempering treatments used in the respective manufacturing processes.
A surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
A surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
GOATever said:
As long as the dimensions are the same, they will both work. The differences will be slight, and be to do with how the discs last / behave under the different conditions they are designed to be optimal for. Road discs will be manufactured to take more extended punishment than the MTB discs, which will be manufactured with a more ‘short sharp shock’ type of usage in mind, rather than extended period / intensity use for the road specific discs. It’s mainly achieved with coatings, and the types of tempering treatments used in the respective manufacturing processes.
A surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
Sram use the same discs for their road and mountain groupsets, as do TRP with their brake sets, so I think I'll stick with the main difference being marketing bA surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
ks.gazza285 said:
Sram use the same discs for their road and mountain groupsets, as do TRP with their brake sets
Yes they do, hence why they tend to be viewed as a bit ‘agricultural’.gazza285 said:
so I think I'll stick with the main difference being marketing bks.
That’s entirely your prerogative.ks.GOATever said:
As long as the dimensions are the same, they will both work. The differences will be slight, and be to do with how the discs last / behave under the different conditions they are designed to be optimal for. Road discs will be manufactured to take more extended punishment than the MTB discs, which will be manufactured with a more ‘short sharp shock’ type of usage in mind, rather than extended period / intensity use for the road specific discs. It’s mainly achieved with coatings, and the types of tempering treatments used in the respective manufacturing processes.
A surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
Just had a quick nose around Shimano's website and a bit of a Google but can't find any info on the 'coatings' you mention.... got a link to where ever you found out about this as I'd be interested in reading more.A surgeons scalpel will ultimately do the same thing to a cut of beef, as a butchers cleaver, but it will achieve it differently.
GOATever said:
The differences will be slight, and be to do with how the discs last / behave under the different conditions they are designed to be optimal for. Road discs will be manufactured to take more extended punishment than the MTB discs, which will be manufactured with a more ‘short sharp shock’ type of usage in mind, rather than extended period / intensity use for the road specific discs. It’s mainly achieved with coatings, and the types of tempering treatments used in the respective manufacturing processes.
I doubt all that very much.There is no difference, apart from style and cooling. Some discs have alloy centres or fins that may help with cooling.
I run plain 6 bolt MTB rotors in my sram rival hydros.
If you can run centre lock then they look neater.
Some styles discussed here: https://www.bikeradar.com/road/gear/article/6-of-t...
Are the "road discs" you were looking at IceTech? If so, they are a laminate of steel-alloy-steel thats why they are expensive.
I run plain 6 bolt MTB rotors in my sram rival hydros.
If you can run centre lock then they look neater.
Some styles discussed here: https://www.bikeradar.com/road/gear/article/6-of-t...
Are the "road discs" you were looking at IceTech? If so, they are a laminate of steel-alloy-steel thats why they are expensive.
Edited by was8v on Tuesday 4th December 16:50
GOATever said:
Road discs will be manufactured to take more extended punishment than the MTB discs, which will be manufactured with a more ‘short sharp shock’ type of usage in mind, rather than extended period / intensity use for the road specific discs. It’s mainly achieved with coatings, and the types of tempering treatments used in the respective manufacturing processes.
Road discs taking more extended punishment than MTB discs? Really? I can only assume your idea of mountain biking is going along fire roads in forests.PaulD86 said:
Road discs taking more extended punishment than MTB discs? Really? I can only assume your idea of mountain biking is going along fire roads in forests.
It’s not the punishment that’s in question, it’s the way the punishment is dished out. MTB braking is generally much harsher, but for a shorter overall time, and in shorter bursts, than say for example a 150 mile road bike ride. Which is one good reason why ( true ) good quality road bike discs are different to MTB discs. By ‘true’ road bike discs, I mean the ( usually more expensive / higher spec ) sort found on actual full on road bikes, not CX, and not ‘gravel / adventure’ bikes.Edited by GOATever on Wednesday 5th December 10:17
GOATever said:
It’s not the punishment that’s in question, it’s the way the punishment is dished out. MTB braking is generally much harsher, but for a shorter overall time, and in shorter bursts, than say for example a 150 mile road bike ride. Which is one good reason why ( true ) good quality road bike discs are different to MTB discs. By ‘true’ road bike discs, I mean the ( usually more expensive / higher spec ) sort found on actual full on road bikes, not CX, and not ‘gravel / adventure’ bikes.
Having ridden 6 of Scotland's 10 apparent hardest bike routes (according to a book of road biking rides), all of which have a lot of long and steep descents I can say with confidence my MTB brakes see much longer periods of sustained use. The rear, certainly. Your point about the braking being harsher is valid, but on long steep descents the brakes are often on for long periods to control speed. Seeing discs change colour with heat isn't unknown. My road bike still had rim brakes and I can guarantee on some of the MTB descents I do a set of those would be melted to nothing before the half way point!Edited by GOATever on Wednesday 5th December 10:17
Edited by PaulD86 on Wednesday 5th December 14:03
aea730 said:
Is there and reason provided I get the right diameter that I can’t put something like a Deore or XT disc on. Presumably if it will stop a mountain bike it will do the same for a road one.
There are some potential differences beyond diameter, though nothing like like some of the drivel posted above.There are some differences in thickness between systems (not road or MTB specific, just generally), though I have never seen a variation so wide as to prevent fitting and use. The sole exception here is the much thicker hope vented discs, but since they are rather spendy, you are not going to buy them by accident.
Floating discs can be quite wide in the carrier/rivet section, and it is fair to assume that the tighter clearances on road forks in particular may result in some discs not clearing the forks, necessitating the use of non-floating plain discs.
Given the much higher flexibility of road forks, some discs with larger sized cut outs _may_ set up harmonic vibrations leading to fork judder when braking. You can't predict this for any given disc/fork combo, and it isn't a common problem so isn't worth worrying about.
The above are all minor edge case issues, and the general answer, most of the time, is that any old disc of the correct diameter will work just fine.
Cabinet Enforcer said:
nothing like like some of the drivel posted above.
I don’t see any “drivel”.........Oh, hang on.........
Cabinet Enforcer said:
Given the much higher flexibility of road forks, some discs with larger sized cut outs _may_ set up harmonic vibrations leading to fork judder when braking. You can't predict this for any given disc/fork combo, and it isn't a common problem so isn't worth worrying about.
Cabinet Enforcer said:
The above are all minor edge case issues, and the general answer, most of the time, is that any old disc of the correct diameter will work just fine.
That’s right.As others have said, most discs should be fine.
The larger rotors often come in a slightly thicker gauge, but I suspect a road bike will use 160mm rotors, and be pretty standard with the MTB marketed equivalent (usually 2mm thick).
You can run 6 bolt to centrelock adaptors - I have them on my Ritchey wheels, mainly because I could get a £1,000 wheelset for £250 because it's centrelock, and they're lighter than the E13 and Enves anyhow.
As has been correctly said upthread, the floating rotors can foul because of the wider rivet used in the design = Hope are an excllent choice but may be a bit tight in this respect.
The larger rotors often come in a slightly thicker gauge, but I suspect a road bike will use 160mm rotors, and be pretty standard with the MTB marketed equivalent (usually 2mm thick).
You can run 6 bolt to centrelock adaptors - I have them on my Ritchey wheels, mainly because I could get a £1,000 wheelset for £250 because it's centrelock, and they're lighter than the E13 and Enves anyhow.
As has been correctly said upthread, the floating rotors can foul because of the wider rivet used in the design = Hope are an excllent choice but may be a bit tight in this respect.
gazza285 said:
Have you told bugeyewrx about these disc coatings yet?
No I haven't heard anything about them yet 
I was really interested to hear how they deal with the disc getting thinner as it wears. Perhaps the coating is only for use in the first couple of miles?
Cabinet Enforcer said:
Given the much higher flexibility of road forks, some discs with larger sized cut outs _may_ set up harmonic vibrations leading to fork judder when braking. You can't predict this for any given disc/fork combo, and it isn't a common problem so isn't worth worrying about.
Ironically I've experienced this with a set of carbon forks on a rigid mountain bike 
You could see the fork vibrating backwards and forwards under braking.... bit disconcerting but didn't seem to cause any real problems.
Edited by bugeyewrx on Thursday 6th December 17:26
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