On 24 Mar 2005 23:10:17 -0800, "Kooner" <j.kooner@attbi.com> wrote:
Hello,>but, the pad still rubs. I can see a slight wobble in the front rotor>as is spins.>Kooner
If you can see the wobble, the rotor is too warped. Take it back to the shop and insist on getting a new rotor. Warped rotors can contribute to brake judder, which is an annoyance you shouldn't have to put up with on a new bike.
Kinky Cowboy*
*Batteries not included May contain traces of nuts Your milage may vary
I just bought a 2004 GT I-Drive 2.0 bike and I believe there is> something wrong with the front rotor. This bike has mechanical disc> breaks.> The brake pads rub the rotor ever so slightly in the same spot as the> wheel rotates. I spent a few hours adjusting the whole brake assembly> but, the pad still rubs. I can see a slight wobble in the front rotor> as is spins. I took the bike back to where I bought it. The bike> mechanic agreed the rotor was slightly warped so he bent/flexed it a> little with his hands! The rotor wobbles less but, the pad still rubs.> The rear pad and rotor is perfect. I mean, there is a hair of a gap> between the rotor and pads and there is absolutely no rubbing on the> rear rotor. So, my questions are:>
1. Is there a flatness or wobble specs for bike rotors?> 2. Is in normal for the front pads to rub? What if the bike is> turning?> 3. What is the annoying vibration sound coming from the front> rotor/pad assembly when I'm riding? Is it something to do with the> floating or sliding caliper?> 4. What else can I do or try?>
Any help would be appreciated.>
Kooner
Clearance between pads and rotor is in the range of 0.6 to 0.8 mm (depending of manufacturer). You should be able to set the pads to that clearance and not have any rotor touching. If the rotor touches anywhere through it's rotation it is out of specification. Ask your shop for a replacement.
1. Is there a flatness or wobble specs for bike rotors?
Probably, but these won't be to the nanometer.
2. Is in normal for the front pads to rub?
No, unless the pad is much too close to the rotor.
What if the bike is> turning?
What if it is?
3. What is the annoying vibration sound coming from the front> rotor/pad assembly when I'm riding? Is it something to do with the> floating or sliding caliper?
Might just be the rubbing you're experiencing. If you're hearing the noise while braking, the sound is of the rotor holes going past the clamped pads.
4. What else can I do or try?
Rotors are easily trued; no need to go to the LBS. Turn the wheel and mark the spot where the rotor is rubbing on the pad. Get an adjustable wrench and clamp it on the rub spot, and gently(!) bend the rotor away from the rub. Trial and error will show you the appropriate amount of bending on the rotor to eliminate rub. >
Any help would be appreciated.
Rotors will get out of true at some stage, especially when you use the brakes for prolonged periods and the rotor gets quite hot.
"Kooner" <j.kooner@attbi.com> wrote in message news:1111814010.222645.321790@l41g2000cwc.googlegroups.com...> Jose Rizal wrote:>
Kooner:>>
1. Is there a flatness or wobble specs for bike rotors?>>
Probably, but these won't be to the nanometer.>>
2. Is in normal for the front pads to rub?>>
No, unless the pad is much too close to the rotor.>>
What if the bike is>> > turning?>>
What if it is?>
When I'm riding the bike and making a sharp left or right turn, I can> hear a med to high pitch vibrating sound. It's always there when I make> a sharp turn. The front wheel is not vertical during a sharp turn so,> I'm thinking that the rotor or pad assembly is shifting a fraction of a> millimeter?>
...> 2. Is in normal for the front pads to rub? What if the bike is> turning?...
Bicycles do not produce significant lateral loading on the wheels while turning, so this should not cause brake rub.
Trikes on the other hand impose lateral loads on the wheels while turning, and a slight ringing indicating very minor rubbing of the disc from one pad is not uncommon.
-- Tom Sherman - Earth (Downstate Illinois, North of Forgottonia)
