Cycling UK Forum

Back on June 14 2017 I asked for advice regarding buying a bike with a cassette or a triple in the end I purchased this Cannondale Synapse 11/30 -34/50. Gear wise something I shall practice with get used too and enjoy. Back to my quiry I notice the front disc is noisy when braking, my mechanic says its due to the air holes in the disc and its a feature of this Braking system ?. Is it ?. Its a bit embarrassing making all that racket , do I Get used to it the same as the Gears ? Cheers T.

Hmm, pretty much ALL rotors have holes in them . . .

Three thoughts:
1 Is the rotor out of true? - even a small amount can make them squeal
2 Is the rotor dirty/have grease on it? - if so, clean it with a specialist cleaner for disc brakes (other stuff can/will contaminate the pads)
3 Are the pads contaminated? - swapping them is almost the only way to find out

Rob

Are they BB7s? If so they've got a reputation for brake squeal especially in the wet. New pads, is it organic best for reduced sqeal?

BTW with my BB7s no amount of cleaning gets rid of the squeal.

if they are sintered pads they will work well in the wet, last OK too but be rather noisy. If they are organic pads then everything is different.

The noise with sintered pads is almost a kind of grinding sound. Some folk can't stick it. There will still be some noise with organic pads though. You probably need the disc holes (they are thought to improve wet weather braking and help dissipate heat) but they do help to make a noise; there is a kind of thwup-p-p-p noise which is the (now hot and expanded) air popping out of each hole as it comes out from behind the brake pads.

If you have a squeal, that is a different matter. Usually it can be reduced or eliminated, but not always.

cheers

Another cause: Does the pads catch the 'spokes' of the rotor? Despite running the same size rotors on different wheels, one wheel had more braking noise than the other and it was down to the pads hitting the 'spokes' of the rotor, it wasn't a great deal of difference, only 1-2mm but it was enough to annoy the hell out of me till I cured it.

Brucey wrote:If you have a squeal, that is a different matter. Usually it can be reduced or eliminated, but not always.

cheers

I've got bad wet weather squeal on my bb7s. Stops well enough but squeals badly unless prolonged braking when the squeal fades. I used to hate it and played around to try and eliminate. Stopped it dry weather squealing. I now don't mind it and have even found a use for it.

On mixed use paths I encounter a lot of pedestrians and cyclists with headphones on or using phones, totally oblivious to anyone else. I found out a well timed squeal is heard when a bell isn't. You get a bit of speed then pull hard on your brakes. As it fades you ease off the brakes and might get another squeal in. They recognise the squealing brakes as something is about to hit them which.makes them jump out of the way then look back at what was about to hit them. Not a fan of scaring ppl but seriously dislike ppl blocking the path for others.

BTW brucey, how can you stop that wet weather squeal on BB7s?

all you can do is to try all the usual tricks. If you are lucky one of them works, and if you are unlucky none of them do.

cheers

regarding the above, following the advice given I bought some disc cleaner and simply gave front disc a wipe over with the solution, what a difference straight away brakes a lot better. I tried to remove the disc from wheel but found its not a 3or 4 mm allen key. when I do get the wheel off I can do a real cleaning job. What key sort /type Do I need ?. Once again thanks for the help.T

the correct key is usually a Torx one. Torx keys come in different sizes... I forget the usual size (T25 or T27...?), but many multitools have that size key on these days.

cheers

You need a T25 torx key for rotor bolts.