Thank you for this great overview, highly appreciated! Could you elleborate on how to fix No4?roselend wrote: ↑Fri Jun 04, 2021 4:37 pmSome tips for Shimano road brakes from the proffesional peleton:
1: 140 front and back. The 160 warps a lot under heat from descending, 140 is less affected. XTR warps less than Dura-Ace. More sturdy construction.
2: Discs that warp under heat and heavy braking is normal, they always warp inwards to the hub. It will straighten out when cooling down again, this can happen quite fast.
3: Brakes that squeel are not normal, squeeling is a indication that there is something wrong.
4: Make sure your flatmounts of your frame are straight. 80% of frames coming out of factory are not perfectly straight. What happens is that the caliper is at a slight angle. Every time you brake if forces the disc in a unnatural angle and this makes noise. Your pads will wear out crooked. When the caliper is not straight and you do some heavy braking the disc can warp inward and actually start dragging on the alumunium of the caliper, instead of dragging on the pad where it should drag. This occurence has a very distinctive metal on metal noise.
5: Use a soft brake pad. Shimano K03S for example, this one makes less noise. Braking feels a bit softer. It's a cheaper version pad. A lot of Pro Teams use it.
5: Degrease your new pads and discs with 96% alcochol BEFORE wearing them in.
6: Always wear in your pads AND dics. On a machine, or on a stretch of downhill road. Replicate normal braking. 10 sec on, 5 sec off, 10 sec on, 5 sec off etc. The point is to have the pad material on both pad and disc. This creates a much more effiecent braking surface with less heat being generated.
7: Never ever touch your pads and disc with your hands. One greasy finger is enough to cause problems.
8: Never ever clean your pads and discs with a sponge, towel, cloth etc. This one can also be greasy, although it sometimes can't be seen by the naked eye. Just soap and rinse off with water is enough. A disc doesn't want to be spotless clean. Spottles clean = smooth = more heat being generated.
9: Never use degreaser on pads and discs. You're also washing off the pad material on the disc. This is the stuff that needs to stay on for optimal braking. Soap is no problem but can leave a thin film on the pads and disc, this brakes of easily after 1 or 2 times. It's no problem.
10: Replace pads more often! When they start making noise there's probaly some oil or grease on them.
11: Organic pad material can be burned easliy from heavy braking, the pads wil glaze. Replace.
12: Disc can not burn, but the defenitely can warp and be permanelty warped from heavy braking. If it's impossible to straighen again. Replace.
13: When you replace a disc, always replace the pads too.
14: For a quick fix, if you dont have new pads in house you can always try to sand off the 'contaminated' top layer of the brake pad. This sometimes works if it's not too bad.
15: Never do a full bleed right away when you're having problems with your Shimano brakes. The problem is most likely air, which causes spungy feeling brakes. Air bubbles can be removed from the top. New oil also has micro bubbles of air inside.
16: Check your oil reguarly with the bleeding pot on top of the shifter. Micro air bubbles inside the oil, caliper or shifter can clog up to 1 big air bubble. Tap the brakes and tilt the bike forward and backwards. A air bubble can be caught behind the oil chambers inside the shifter. If done correctly all air bubbles should come out at the top.
17: If the oil at the top coming out is black colored your oil is contaminated with water. Water can come in through all linkages and pistons. Water compresses, oil does not. So the water causes spungy brakes or pistons not coming back properly. Water inside the hose can also evaporate under heavy braking, which creates sudden new air bubbles. Which can be quite dangerous.
18: Dirty pistons eventually will clog up and they will stop working or returning inside the caliper. The best way to clean a piston is by lubracting it in it's own mineral oil. You can do this by pushing back the pistons inside the caliper with a tool and brake a few times again, repeat until clean.
Hope this helps you guys out a bit.
So what is the definitive answer about noisy Dura Ace rotors?
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PriorPhillip
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You have to face the mounts.. Aka grind it flat. Not something most people will have the tool for. Check with your lbs if they do have the right tools.PriorPhillip wrote:Thank you for this great overview, highly appreciated! Could you elleborate on how to fix No4?roselend wrote: ↑Fri Jun 04, 2021 4:37 pmSome tips for Shimano road brakes from the proffesional peleton:
1: 140 front and back. The 160 warps a lot under heat from descending, 140 is less affected. XTR warps less than Dura-Ace. More sturdy construction.
2: Discs that warp under heat and heavy braking is normal, they always warp inwards to the hub. It will straighten out when cooling down again, this can happen quite fast.
3: Brakes that squeel are not normal, squeeling is a indication that there is something wrong.
4: Make sure your flatmounts of your frame are straight. 80% of frames coming out of factory are not perfectly straight. What happens is that the caliper is at a slight angle. Every time you brake if forces the disc in a unnatural angle and this makes noise. Your pads will wear out crooked. When the caliper is not straight and you do some heavy braking the disc can warp inward and actually start dragging on the alumunium of the caliper, instead of dragging on the pad where it should drag. This occurence has a very distinctive metal on metal noise.
5: Use a soft brake pad. Shimano K03S for example, this one makes less noise. Braking feels a bit softer. It's a cheaper version pad. A lot of Pro Teams use it.
5: Degrease your new pads and discs with 96% alcochol BEFORE wearing them in.
6: Always wear in your pads AND dics. On a machine, or on a stretch of downhill road. Replicate normal braking. 10 sec on, 5 sec off, 10 sec on, 5 sec off etc. The point is to have the pad material on both pad and disc. This creates a much more effiecent braking surface with less heat being generated.
7: Never ever touch your pads and disc with your hands. One greasy finger is enough to cause problems.
8: Never ever clean your pads and discs with a sponge, towel, cloth etc. This one can also be greasy, although it sometimes can't be seen by the naked eye. Just soap and rinse off with water is enough. A disc doesn't want to be spotless clean. Spottles clean = smooth = more heat being generated.
9: Never use degreaser on pads and discs. You're also washing off the pad material on the disc. This is the stuff that needs to stay on for optimal braking. Soap is no problem but can leave a thin film on the pads and disc, this brakes of easily after 1 or 2 times. It's no problem.
10: Replace pads more often! When they start making noise there's probaly some oil or grease on them.
11: Organic pad material can be burned easliy from heavy braking, the pads wil glaze. Replace.
12: Disc can not burn, but the defenitely can warp and be permanelty warped from heavy braking. If it's impossible to straighen again. Replace.
13: When you replace a disc, always replace the pads too.
14: For a quick fix, if you dont have new pads in house you can always try to sand off the 'contaminated' top layer of the brake pad. This sometimes works if it's not too bad.
15: Never do a full bleed right away when you're having problems with your Shimano brakes. The problem is most likely air, which causes spungy feeling brakes. Air bubbles can be removed from the top. New oil also has micro bubbles of air inside.
16: Check your oil reguarly with the bleeding pot on top of the shifter. Micro air bubbles inside the oil, caliper or shifter can clog up to 1 big air bubble. Tap the brakes and tilt the bike forward and backwards. A air bubble can be caught behind the oil chambers inside the shifter. If done correctly all air bubbles should come out at the top.
17: If the oil at the top coming out is black colored your oil is contaminated with water. Water can come in through all linkages and pistons. Water compresses, oil does not. So the water causes spungy brakes or pistons not coming back properly. Water inside the hose can also evaporate under heavy braking, which creates sudden new air bubbles. Which can be quite dangerous.
18: Dirty pistons eventually will clog up and they will stop working or returning inside the caliper. The best way to clean a piston is by lubracting it in it's own mineral oil. You can do this by pushing back the pistons inside the caliper with a tool and brake a few times again, repeat until clean.
Hope this helps you guys out a bit.
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Just the opposite on my 105 discs. Hard braking causes them to howl loudly.GregR wrote:I had noisy discs at the beginning of this season. They were quiet all last year, and I had done a disc and pad replacement on the front. On the back, just cleaned the caliper and disc with alcohol. (not the pads.) Tried everything, what worked was hard braking from 50 kmh or so. One wheel at a time. Got everything nice and hot, and the noise was gone. KO3Ti pads. I read that road bikes are susceptible to squeal because we tend to brake lightly a lot, thus glazing the pads. Hard braking burns the glaze off. YMMV.
I have had this work also, but it does require the pads and discs to be clean (free from contamination) initially. I have also found that braking, hard, from 50kph on the flat usually isn't enough - having a steep hill makes it all much easier to experiment with.GregR wrote:I had noisy discs at the beginning of this season. They were quiet all last year, and I had done a disc and pad replacement on the front. On the back, just cleaned the caliper and disc with alcohol. (not the pads.) Tried everything, what worked was hard braking from 50 kmh or so. One wheel at a time. Got everything nice and hot, and the noise was gone. KO3Ti pads. I read that road bikes are susceptible to squeal because we tend to brake lightly a lot, thus glazing the pads. Hard braking burns the glaze off. YMMV.
If this is braking in "dry" conditions, then I think there's some contamination of pads and/or discs - it may not be visible, but it's there. In the wet, they all howl - wet meaning a steady supply of water to the disc e.g. rain, spray, high humidity etc.
Yeah, that has always worked for me. As you said, however, YMMV.GregR wrote: ↑Thu Jun 17, 2021 7:10 amI had noisy discs at the beginning of this season. They were quiet all last year, and I had done a disc and pad replacement on the front. On the back, just cleaned the caliper and disc with alcohol. (not the pads.) Tried everything, what worked was hard braking from 50 kmh or so. One wheel at a time. Got everything nice and hot, and the noise was gone. KO3Ti pads. I read that road bikes are susceptible to squeal because we tend to brake lightly a lot, thus glazing the pads. Hard braking burns the glaze off. YMMV.
