Front brake locking on by itself?

[Danny]

Is the brake caliper bolt tight? The one that affixes it to the fork.

It’s not loose if that’s what you mean. How tight should it be?

 

[figbat]

It’s not loose if that’s what you mean. How tight should it be?

It should be tight and the caliper should not be free to ‘wobble’ (although it should be able to move readily).

 

[Misterphil]

I was recently on a long ride with lots of steep decents and found I was regularly getting a loud vibrating sound from my front wheel which was like a brake locking on even though I wasn't touching the brake lever. . I also only got the sound when I was going above 17 mph. Often this started if I hit a small bump in the road and usually went on for about 30 seconds or until I hit another minor bump.

As this was mostly happening when I was going down quite steep and technical descents I was reluctant to lean over too much to try and work out if it was really caused by my brakes locking on somehow or was the result of something else vibrating or rubbing.

I was riding a Cannondale Synapse with a Shimano 105 groupset.

Any ideas about what could have caused this?

Check the brake outer has not failed where it goes into the top tube, I had the same symptoms with mine. it is a weak point in the design where the outer over flexes and fails.