Adapter for 180mm on flat-mount discs?
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  1. #1
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    Adapter for 180mm on flat-mount discs?

    It seems that flat-mounts are made for 140/160 front, 140 rear, that's it. Flip the orientation of the fork adapter for 140 or 160. Now, how can I use 180 in front?? Is there a flat-mount adapter for this?? Apparently there's an adapter for the rear to use a 160 instead of a 140, so I guess it could be mounted on the fork adapter? Two adapters, that sounds super ugly and many screws. Is there a one-adapter solution for 180mm? Thanks -

  2. #2
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    What type of bike needs a 180mm front rotor?

  3. #3
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    Flat-mount calipers are not meant to be run with 180mm rotors, so anything you cobbled together would be compromise or hack.

    Like Nova, I have to ask: why not just run a 160mm rotor?

  4. #4
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    As the previous guys posted...what's the thinking behind a 180mm rotor? If you actually 'need' a 180 rotor to slow yourself down what you really need is a different bike. There is no good way to put a 180mm rotor on a bike w/ flat mount calipers.
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  5. #5
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    Whether I need a 180mm rotor is irrelevant. I was asking the question out of genuine interest. It is possible to use 180mm with post-mount brakes, so it would make sense to be able to do it as well with flat-mount brakes. What a surprising design, that this is not possible.

    By the way, not so long ago, people were saying that disc brakes in general didn't make any sense on road bikes. Other people were saying that wide tires are 'slower' etc...

  6. #6
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    Quote Originally Posted by Pierre View Post
    Whether I need a 180mm rotor is irrelevant. I was asking the question out of genuine interest. It is possible to use 180mm with post-mount brakes, so it would make sense to be able to do it as well with flat-mount brakes. What a surprising design, that this is not possible.

    By the way, not so long ago, people were saying that disc brakes in general didn't make any sense on road bikes. Other people were saying that wide tires are 'slower' etc...
    Uhmmm no. Flat mounts are pretty much specifically for road bikes. The design and engineering is such that 160mm is the largest rotor that everyone involved is comfortable putting on a road bike. The stopping power generated is good for the majority of riders. If you increase the size of the rotor you increase the leverage created by the brake system on the frame and fork so you'd need to increase the strength of both. To answer your question...again...no, it's not possible to do it safely. I won't make any comments about whether you (think you) need a 180 or not.
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  7. #7
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    Quote Originally Posted by Pierre View Post
    Whether I need a 180mm rotor is irrelevant. I was asking the question out of genuine interest. It is possible to use 180mm with post-mount brakes, so it would make sense to be able to do it as well with flat-mount brakes. What a surprising design, that this is not possible.

    By the way, not so long ago, people were saying that disc brakes in general didn't make any sense on road bikes. Other people were saying that wide tires are 'slower' etc...
    I didn't really care why you wanted to do it until you made a big deal out of not wanting to explain why you wanted to do it, now I'm really curious.

  8. #8
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    Quote Originally Posted by masont View Post
    I didn't really care why you wanted to do it until you made a big deal out of not wanting to explain why you wanted to do it, now I'm really curious.
    Well, I just picked up a 18 Kona Rove NRB.
    I weigh 245 lbs.
    Yeah, I'd like to lose some weight which is another reason I got the bike.
    160 is nowhere near enough to stop my fat ass.
    Lots of people in my situation.

  9. #9
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    Quote Originally Posted by slope View Post
    Well, I just picked up a 18 Kona Rove NRB.
    I weigh 245 lbs.
    Yeah, I'd like to lose some weight which is another reason I got the bike.
    160 is nowhere near enough to stop my fat ass.
    Lots of people in my situation.
    160 is plenty. 140 is fine as well.

    Unless you are running really wide tires, like 40mm or larger and carrying a touring load, the issue is going to be tires breaking contact when the brake works great.

  10. #10
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    Quote Originally Posted by slope View Post
    Well, I just picked up a 18 Kona Rove NRB.
    I weigh 245 lbs.
    Yeah, I'd like to lose some weight which is another reason I got the bike.
    160 is nowhere near enough to stop my fat ass.
    Lots of people in my situation.
    160 will work. If it doesn't get a different brake set up.
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  11. #11
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    Quote Originally Posted by slope View Post
    Well, I just picked up a 18 Kona Rove NRB.
    I weigh 245 lbs.
    Yeah, I'd like to lose some weight which is another reason I got the bike.
    160 is nowhere near enough to stop my fat ass.
    Lots of people in my situation.
    On a bad day I weigh the same as you.

    I ride gravel and road in a hilly region, and I have 10k plus miles on 140/140 and 160/140 and have not had an issue. Even with quick emergency stops. As someone else said, in that situation, you are probably going to lock up a tire, regardless of the size of the rotor.

    The one scenario you probably need to be careful of is really long descents where you have to stay on the brakes for an extended period. Just be aware of this, use good technique to keep the brakes cool, and don't get in over your head. You should be fine.
    Last edited by Finx; 02-11-2019 at 06:27 PM.

  12. #12
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    Hmm....I am running cable disc (TRP Spyres).
    I am also running wide tires but can't come anywhere near stopping on a dime.
    Not even close.
    Maybe I'm expecting too much of a "road bike".
    Looking at changing pads perhaps.

  13. #13
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    Quote Originally Posted by slope View Post
    Hmm....I am running cable disc (TRP Spyres).
    I am also running wide tires but can't come anywhere near stopping on a dime.
    Not even close.
    Maybe I'm expecting too much of a "road bike".
    Looking at changing pads perhaps.
    Have you braked hard enough? to the point that the front tire is almost skidding? Practice this hard braking technique in a straight line. If you've clamped on the front brake lever as hard as you could (ie., you're appling all 4 fingers) and you still cannot get the front tire to almost lockup and skid in a straightline, only then would you need to consider going to a more power brake setup.

    now to lessen the chances of you folding the front wheel under hard braking, you should perform the above test in a series of increasing speed attempts, this will allow you to feel and hear how the tire is behaving. If you sense that tire is about to lock and skid, just release the front brake and you'll roll out it safely.

    but I do think that guys in your weight category is better off with an 180mm rotor though.

  14. #14
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    Quote Originally Posted by slope View Post
    Hmm....I am running cable disc (TRP Spyres).
    I am also running wide tires but can't come anywhere near stopping on a dime.
    Not even close.
    Maybe I'm expecting too much of a "road bike".
    Looking at changing pads perhaps.
    I'll bet a dollar your brake isn't set up correctly. You can go from very powerful to won't do a damn thing in less than 10mm of cable if you don't adjust them correctly.
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  15. #15
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    Quote Originally Posted by slope View Post
    Hmm....I am running cable disc (TRP Spyres).
    I am also running wide tires but can't come anywhere near stopping on a dime.
    Not even close.
    Maybe I'm expecting too much of a "road bike".
    Looking at changing pads perhaps.
    Your problem isn't rotor size. Plenty of big guys do just fine on 160.

    Either you need new pads and a rotor cleaning, your bike is brand new, or your brake just isn't set up properly at all. Any one of those will cause you to not have the power and modulation you should, and that's totally independent of rotor size.

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