Haha yes. I'm just thinking if you're out on a ride/race and not going to stop or not able to fix it.

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Blog: https://davidkoppeltriathlon.blogspot.com/
Coaching: https://dkendurance.com/

I used to have rim brake rub only with certain wheels and only when climbing / out of saddle. Worst case scenario I’d simply unclip the brake(s) when going up.

I tend to have disc brake rub in all situations, until fixed (in order: checking if rotor is true, checking if caliper is aligned, pushing the pads to the side, taking pads off and pushing pistons to the side, cleaning sticky pistons). Once I wasn’t able to fix, because the piston’s suction didn’t work properly…

Disc brakes have more stopping power ergo rub is a more powerful amplifier? Just adding to your fears :)

Just get a rotor adjustment tool and fix it at home if it's only one section of the rotor and it's not consistently floating and rubbing off center to one side.

Otherwise, there are some cool adjustment tools. I haven't bought this exact one, but one like it in principle and it's easy to center the break over the rotor with it
https://www.amazon.com/...ps%2C169&sr=8-17

But sometimes the rotor is bent a little just on one side so you need the bender tool to ever so carefully fix it.

Braking torque=coefficient of friction * normal force * length of lever arm

This problem can have a lot of layers to it. I've had all kinds of brake rub issues the last couple of years (on both rim & disc brakes). Identifying the problem is easier said than done, but it's definitely worth going to a bike shop (or three) to get it sorted out, since it can cost you *a lot* of time.

One of my underlying issues was loose bolts connecting the rear drop-outs to the frame, though it took me a long time to notice that - and for some reason most mechanics never seem to check these. No amount of truing the disc works if those bolts are not tight!

Also, wheel flex can be a culprit (at least with rim brakes), and if you have tires that are slightly too wide for the frame, they can rub as well. (Tire rub feels about the same as brake rub when you're riding.) I ended up getting the stiffest wheels I could find, and switching from 28 to 25mm tires.

The other piece (for me) was user error. I got so frustrated with my brake rub & tire rub problems that I would basically go to war against my bike, and "attack the pedals with every stroke" - as some people I ride with put it - which of course caused more rubbing. I could induce brake rub in pretty much any configuration if I mashed the pedals hard enough. Consciously thinking about pedaling smoothly makes a huge difference.

Happy to say I finally seem to have solved most of the issues - went about 2mph faster at IM Maryland than most of the races I've done the last couple of years. So definitely worth taking the time to sort it out, even though it can be a super frustrating problem!

Cheers,
Ginger