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Is 160mm to 180mm Rotor Always an Upgrade?

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Is 160mm to 180mm Rotor Always an Upgrade?

Old 03-09-19, 07:40 PM
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michaelm101
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Is 160mm to 180mm Rotor Always an Upgrade?

I recently had to swap out my rear TRP Spyre (road) for a Spyke (mtb) and, indeed, it's working much better with my flat bar levers.
NOW, I need to swap out the front.
The cost of going to a Spyke with my existing 160 front rotor is almost the same as getting the 180mm kit that includes a new180mm rotor. I just need to get the 5.00 adapter...

BTW, this is for a rigid, carbon frame "backpacker" / lightweight touring bike. I am 160lbs and will load no more than 40-50lbs on the bike at any given time. The tires used are: 25 x 700 slick, 35 x 700 multi-purpose touring, & 27.5 x 2.1 off-road/knobby.

Can anyone tell me that, aside from the slight added weight, it's not always an upgrade to go to a larger rotor? Thanks very much in advance!
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Old 03-09-19, 09:04 PM
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The larger the rotor the more any runout will cause pad/rotor rub. The larger rotor might contact the frame/fork is clearances are already tight with the 160.

I guess it depends of what you define as an upgrade. Andy
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Old 03-09-19, 10:55 PM
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oversimplifying, "always"..

I have a fork that won't accept larger than 160 ... I cannot see yours..
160 is always smaller than 180.. that I can say with confidence..

Why is it important to ask?
You smokin big, long, high speed downhills? no? it may not matter..





...

Last edited by fietsbob; 03-22-19 at 12:04 PM.
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Old 03-09-19, 11:36 PM
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I told the bicycle shop when I ordered my custom touring bicycle I wanted 203mm rotors. They did what they wanted and it had 160mm when they delivered it. I put a 180mm on the front and a 203mm on the rear. The 180 on the front is the largest It can handle. There is an improvement in braking. The run out you speak of is easy to fix.
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Old 03-11-19, 12:17 PM
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As quoted from the bike frame manufacturer:"....The frame is designed for up to a 160 rotor. You might be able to go larger, but you'll run into the issue that the braking power could be too much for the grip offered by the tires causing a front wheel washout..."
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Old 03-11-19, 01:21 PM
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Disk brakes are so weak compared to proper rim brakes. I did check with the manufacture and they told me I could put the largest rotor that would fit on. I did specify a frame that could handle a 350lbs ryder also. I hear so much about brake safety, I am starting to think the people that conjured up layer lips are sticking there nose into disk brakes also. Washing out the front wheel can happen on rim brakes even easier because of lack of modulation. Attempting to solve all issues that can happen by limiting usability by one size fits all engineering is not something I am willing to identify with. I am not with the crowd that believes you should adjust your brakes so it is impossible to be thrown over the bars. Even though the CPSC proposed this. You can go over the bars with no brakes. Braking is about balance as it is about stopping.
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Old 03-11-19, 05:19 PM
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For your application (particularly rhe carrying 50 lbs part) I think a 180 in the front would be nice.

I run 180/160 (F/R) on all my mt bikes. It seems lime a good balance as I am generally braking harder in the front.

On my road/gravel bike I have 160s front and rear. It seems like plenty, but I am not carrying 50 lbs.

The only downside that I have found to larger rotors (besides weight) is that they can get a little too sensitive and grabby if you go too big. I ran a 203 on one of my mtbs and found it a little too sensitive in loose conditions, and way more braking power then I needed. Sizing down to 180/160 felt better to me. But some people like big rotors for similar applications. This is probably less of an issue with road riding as maintaining traction (not locking the wheels) is less of an issue on pavement.
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Old 03-11-19, 05:24 PM
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The larger the rotor, the deeper the incision.
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Old 03-11-19, 05:28 PM
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Originally Posted by wgscott View Post
The larger the rotor, the deeper the incision.
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Old 03-11-19, 06:19 PM
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More braking power isn't always a plus. Granted, my experience is all with rim brakes. The single biggest upgrade I ever did for my road bikes on mountain descents was to swap regular brake levers for V-brake levers. (I did it because the V-brake levers had huge hoods that looked great for cliimbing on. Didn't realize they were V-brake levers until I had them on the bike. One of my early rides with them was up McKenzie Pass. The descent back down was fast and fun, But I came into on blind corner and realized very late that it was much tighter (and steeper) than I thought; that there was no way my pedal wasn't hitting. (I was riding fix gear.) Grabbed two fistfuls of brake, fueled by adrenaline. And nothing happened, Nothing except I slowed down very rapidly and made the corner easily. No skidding, no lock-up.. Nothing exciting. Just a really quick massive slow-down.

I now run V-brake levers on all my good bikes. There is the drawback that braking does require more effort and is not super braking from the hoods, but I have always preferred to do my big-time braking from the drops and spend a lot more time there.

So the question I'd be asking is "do I need that much power? Do I want that much power?" (You are my weight and when I toured I rode with !30-40 pounds of gear. I used centerpull brakes on one bike and cantilevers on another. They worked just fine for me. Granted I did not do mountain descents except Mt Diablo and the Oakland/Berekeley hills in CA after stealth camping (and packing quite light).

Ben
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Old 03-13-19, 08:33 AM
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Originally Posted by wgscott View Post
The larger the rotor, the deeper the incision.
I LOL'd.
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Old 03-13-19, 08:41 AM
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Originally Posted by michaelm101 View Post
As quoted from the bike frame manufacturer:"....The frame is designed for up to a 160 rotor. You might be able to go larger, but you'll run into the issue that the braking power could be too much for the grip offered by the tires causing a front wheel washout..."
BS.

-Tim-
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Old 03-22-19, 10:40 AM
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If the setup can be assumed to be equal (which is not a safe assumption) and the larger rotors will fit your frame or fork, then yes, it is always an upgrade. You will benefit from added leverage against the movement of the wheel (80mm lever to 90 mm lever, so 1/8 increase), and a similar increase in rotor area across which heat can dissipate.

However, this is not to say it is at all necessary - I have weighed up to ~270 lbs and never found my Shimao hydraulic calipers and 160mm rotors to be at all insufficient, even on steep and nasty off road trails and longish descents. And, as others have mentioned, the manufacturer of the frame and fork may recommend against it.
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Old 03-22-19, 10:51 AM
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Timely post for me as I'm switching from 160 to 180. Why? More stopping power. Why not? I need both new pads and rotor, so the only additional cost is the brake adapter ($10) and a little more $ for a 180 vs a 160 rotor ($5). And yes, my fork can handle it. In fact, the factory spec for this bike (I custom spec'd mine) uses a 180. The shop spec'd mine with 160 as that's what was in stock and I didn't want to wait for parts. So, in my case, no hassles or drawbacks to doing this.
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Old 03-22-19, 12:17 PM
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Originally Posted by bikeme View Post
Timely post for me as I'm switching from 160 to 180. Why? More stopping power. Why not? I need both new pads and rotor, so the only additional cost is the brake adapter ($10) and a little more $ for a 180 vs a 160 rotor ($5). And yes, my fork can handle it. In fact, the factory spec for this bike (I custom spec'd mine) uses a 180. The shop spec'd mine with 160 as that's what was in stock and I didn't want to wait for parts. So, in my case, no hassles or drawbacks to doing this.
Great! I'm getting the 180 that comes with rotor for 5-10 bucks more. The adapter's on it's way for 5 bucks. I'll give it a shot and I can always go back to 160...
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