MTB front disc 180 or 160?

I had 180 front disc on my scott spark 100/100 and now I changed wheels so I have to buy discs/rotors and thinking to put 160 on the front. Brakes are shimano xt.

I usually ride XCM but sometimes also XCO.

Does anyone moved from 180 to 160 and how it went?

Larger disc = more braking power.

Also usually you want the stronger brake at the front.

I’d probably stick with the 180. Why do you want a smaller rotor?

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180, the minimal weight savings with a 160 isn’t worth the stopping power you’ll give up.

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I was told that 180 is too harsh for the fork…

What fork?

Sounds like garbage ideology to me. Could be relatively easy to search other bikes set with the same fork and cross check rotors specified.

My gut says keep 180.

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What fork is it? If it clears/fits a 180 and you’re already running one I don’t see the issue? If you’ve gotta just save the weight be prepared to give up stopping power. I’ve done this myself and quickly went back to 180, I even run 180 in the back now on my XCM build. If you don’t live or race in the mountains maybe it’s ok?

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Stick with 180 mm. They offer more stopping power (due to the larger lever), have a larger heat capacity and the weight penalty is completely negligible.

That doesn’t sound right. All quality mountain bike forks (with the possible exception of downhill-specific forks) should accept 180 mm discs. 180 mm discs are the default in the front on most mountain bikes.

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Like everyone above, I’d have to recommend going to a 180mm. I raced XCO for years as a weightweenie and had 160 - now on 180 and its so much better.

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180

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180 it is :slight_smile:

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I’ve run 180mm on all of my xc bikes and it’s spot on. I like to attack the downhills so stopping is a priority.

I accidently ended up with 160mm discs at the front and decided to keep them. I noticed I am missing the adaptors to late and had to put on the spare 160mm disc to the front. And they are lightweight Storm SL models.
I am using grownup brakes (4-pot Magura MT7) and 65kg so getting good braking power is not a problem. I do a lot of long alpine descents and never had any fading or felt I needed more power.
Now compare that to the brakes I throwed away: Sram level Ultimate TLM. Big part of breaking with these toy brakes was praying.

There’s actually good arguments for putting the largest rotor in the back!
Don’t knock it before you read it :wink: https://enduro-mtb.com/en/rotor-size-myth/

needing a larger rotor in the back because its overheating is a sign of bad riding habits. the front brake is where the stopping power is at, despite what this article (filled with anecdotal bro science?) says.
Although it is true that the rear brake is often dragged a lot to modulate speed, so ok, why not go bigger.
Better modulation with a smaller rotor is also bollocks. A larger rotor means less force is needed at the lever, means better feel, means better modulation.
I’m an automotive engineer, so know a thing or two about this stuff, but whatever. :grin:
Do agree, bigger is better

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You’ve overlooked all of the nuances in the article I’m afraid. For the example the OP is asking about I don’t think the bigger / even bigger rotor choice is pertinent however but the setup, on an enduro bike, might actually make sense if you consider their points. Where’s the bro-science?

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ok, bro science was being a bit hyperbolic.
I now see its about enduro and i was looking at it from an XCO / XCM point of view.

Stil though:

Braking force distribution myth – how do you really brake?

You should use both brakes, period. The most power is in the front brake. You can lean back as much as you want on a descent, the rear brake alone will not slow you down enough. But i understand from an enduro perspective, you you use the rear brake a lot in a dragging fashion to modulate speed, so yes, bigger is a good idea.

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Not every rider is 80kg and on mountainous or hilly terrain. Does a sub-60kg rider need a 180 rotor?

Yeah I’m seeing this as a narrow scope in the world of MTB and there’s no argument where the stopping power is coming from, it’s more about a unique bike set up for a specific task. To add on to your point about using and modulating both brakes, I absolutely agree, but their argument is saying that fast guys might have a tendency to feather the rear brake more while relying on the front for quicker decelerations. Again, this is in the context of an enduro level downhill so I don’t think it’s pertinent here. I read the article with much skepticism too, but after considering the use case and the fact that many forks are not rated/compatible with those huge 220s I left thinking that maybe it’s something I might try myself, on my enduro bike. (Not my XCM bike though).

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i weigh “a bit” over 80 kg and have 180/180 on my Ti XC bike.
I think you are right, this is a very specific use case and a preference of the writer. The idea that bigger discs are better i can agree with, or at least that focusing on smaller rotors to safe weight is nonsensical.

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180… Once you’re used to an increase in stopping power, going the other way feels extremely unsettling.

When I get off of my downcountry bike and hop on the xc hardtail w/160 rotors there are always a few fast downhills followed by abrupt turns that remind me that I really like more braking power.

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