Why are my brakes squealing

[steve-o]

I have Shimano mineral oil brakes on my Ironhorse Azure bike that seem to constantly squeak after 20 or so miles. I have replaced the pads, cleaned and sanded down my rotors, bled the lines and still it persists. After a while the pads begin to shine and squeak slowly starts up again. See pics

I have well over 500 miles on my bike and have beaten it up off and on the road. Mostly road miles.

Is there problems with Shimano mineral oil brake systems? Is there some magic trick to fix these breaks? or is it time to buy another bike?

 

[Slick]

Minute leak in your line?

Maybe you have the same issue I had, and a single tear from a new born baby has compromised your entire brake system.

 

[Big John]

View: https://youtu.be/jdKbUAJNR2w?feature=shared

 

[All uphill]

Are you someone who gently brakes often?

My early experience with disc brakes was not good; I'd not realised that my gentle riding style resulted in nicely polished brake pads that were not very effective at stopping me, but excellent at squealing. Firmer braking resulted in good performance and no squeals.

 

[Slick]

Are you someone who gently brakes often?

My early experience with disc brakes was not good; I'd not realised that my gentle riding style resulted in nicely polished brake pads that were not very effective at stopping me, but excellent at squealing. Firmer braking resulted in good performance and no squeals.

I always wondered why my commuter brakes always worked perfectly yet my Sunday best bike squealed like an intercity approaching a station, until someone pointed that out.