Disk brake variable rubbing on a new bike

[summerdays]

I didn't know whether to start a new topic or high-jack Yellow Fangs one here: http://www.cyclechat.co.uk/forums/showthread.php?p=260703#post260703
(not sure if thats the correct way to link to another thread).

On my new bike (Fergus by the way), my front disk brake is rubbing. I know that initially they have to bed in and the back one is now fine. The front one may need a bit more time to bed in yet.

My problem is not that it rubs all the time but that it only rubs on rotation in one or two places. That would make me think that there was one point that was sticking up. However it changes the rubbing pattern after braking or cornering which makes me think something is moving slightly. It hasn't had its 6 week check yet, although the lbs did fiddle with the brakes a bit to try and remove the rubbing noise.

What I'm asking really is .... should the noise vary with cornering and after braking or is there something that I should be getting investigated at the 6 week check?

 

[Alcdrew]

You like telling us all your bikes name, sure I've seen you do that in another thread.

Whens it due for it's check up?

Doesn't sound anything too serious. My disc breaks sometimes have a rubbing sound after breaking, I have just put it down to the calipers not releasing fully, might just need a bit of oil.

 

[summerdays]

Hmm... where do you oil them ... I was under the impression I had to keep oil as far away as possible .... though it makes sort of sense - from how you had to look after V-brakes. So keeping oil off the disk and pads which bits do need lubricating from a maintenance point of view?

 

[Alcdrew]

Not got a clue. Ask your lbs when you take it in. But it is a mechanism that close and opens, so some part of it must need a bit of oil every now and then. Like you say though, make sure you don't get any on the discs or pads, I've heard if you get it on the pads you might as well throw them away and get another set.

 

[Steve Austin]

put the oil away, its not needed. What brakes are they?

it sounds like the rotors may be warped or the brakes need centring

 

[summerdays]

It is Juicy 3's that came with the bike.

The bloke in the lbs spent 30 mins trying to adjust the position of the pads on Sat, but as I still needed to bed the front ones in then he was finding it very difficult. I think that I've managed to do finally do that to the front brakes this week but I still have this rotational rub that varies in level.

As disk brakes are new to me ... I don't know what is "normal" as opposed to "needs to be investigated".

 

[bonj2]

i used to get this when i had juicy 5s.
IF it's a 'regular' rub once per revolution, it could be that the rotor isn't true.
Try truing it with an adjustable spanner. Work out which bit is untrue, then rotate it so that that bit is not near the caliper then pull it over by about 10 degrees (or until you feel some resistance) with the adjustable spanner and hold for about 10 seconds then recheck.
You can get rotor truing forks for the above purpose but an adjustable spanner works as well.

IF it's just rubbing generally and not regular once per rev. or anything, then that's just avids. I upgraded to formul oro k18s on my bike and don't get it at all with them.

 

[bonj2]

It's normal, not a problem other than the fact it's annoying unless the rotor's so out of true as to cause uneven braking.
Does it do it when still or only when riding?

Seriously just upgrade to either formula or hopes and flog the avids on ebay.

 

[mickle]

Zummerdays moi luvver, don't touch them with a spanner and don't put oil anywhere near them before the end of your warranty period. It is the responsibility of the shop. If you fiddle with your brakes not only are you likely to make them worse you may even invalidate your warranty. Take it back to the shop.

 

[buddha]

This may be a bit obvious, but have you checked that the hub/axle is correctly seated in the dropouts?
I had a similar problem on my old MTB whenever I would remove and then replace the front wheel. Pushing the axle firmly into the dropouts and tightening the QR well solved this.

 

[summerdays]

Ok had a quick check of the QR - I don't think it is this but I hadn't thought of it before now.

And I think I will go with Mickle's advice and leave it to the proper people to sort for now. They are nice and prepared to fiddle with my bike at my LBS but I like to appear as if I have some technical knowledge when I'm talking to them, even though I usually give the game away by asking some daft question. (Although they recognise me and know I don't know so I don't know why I'm tyring)