Brake Judder - loose headset?
Just started riding a new bike with 105 hydraulic discs. Most of the time the brakes are AMAZING but just every now and then I was pulling the front and getting a judder which reverberated through the front forks. Very infrequent, nothing to do with how hard I was braking or from what speed as I tried to reproduce it will all variations on demand and cannot do so. Not related to overheading or dragging the brakes as I tried that deliberately too and it doesnt cause it, plus sometimes when it happens I havent touched the brakes for ages.
Googled it last night and causes seem to be:
1) contaminated rotor
2) contaminated pads
3) rotor thickness variation
4) loose rotor bolts
5) loose front wheel
6) bearings on the front wheel
7) loose headset
The bike is new, the wheels are new. I tried the following:
a) cleaned the rotor with isopropyl alcohol and it still happens
b) checked front wheel tight - OK
c) checked rotor bolts - OK
d) holding the front brake and rocking the bike there seems to be some play in the headset - tightened it up a bit to the point where the play seems to have stopped (bars are still quite floppy though so may need to do some more?)
Short ride into work this morning seemed OK but it was just 4.5 miles so not guaranteed to happen anyway - its affecting my confidence but I guess if I do more miles and it doesnt recur then this will improve.
My question is - why would it have been intermittent if it was any of the above? Would it not happen all the time?
I had done some experiments to see if the cause was the front being more heavily loaded by leaning on the bars or unloaded by taking weight off and pulling/pushing on them and that may have been a contributory factor but I cant reproduce at will and not sure I want to as its a bit scary when it happens(!).
Any thoughts?
If this doesnt cure it then next step I can think of is maybe to swap the front/rear rotors and maybe even pads, and to put the OEM wheels back on the bike.
Googled it last night and causes seem to be:
1) contaminated rotor
2) contaminated pads
3) rotor thickness variation
4) loose rotor bolts
5) loose front wheel
6) bearings on the front wheel
7) loose headset
The bike is new, the wheels are new. I tried the following:
a) cleaned the rotor with isopropyl alcohol and it still happens
b) checked front wheel tight - OK
c) checked rotor bolts - OK
d) holding the front brake and rocking the bike there seems to be some play in the headset - tightened it up a bit to the point where the play seems to have stopped (bars are still quite floppy though so may need to do some more?)
Short ride into work this morning seemed OK but it was just 4.5 miles so not guaranteed to happen anyway - its affecting my confidence but I guess if I do more miles and it doesnt recur then this will improve.
My question is - why would it have been intermittent if it was any of the above? Would it not happen all the time?
I had done some experiments to see if the cause was the front being more heavily loaded by leaning on the bars or unloaded by taking weight off and pulling/pushing on them and that may have been a contributory factor but I cant reproduce at will and not sure I want to as its a bit scary when it happens(!).
Any thoughts?
If this doesnt cure it then next step I can think of is maybe to swap the front/rear rotors and maybe even pads, and to put the OEM wheels back on the bike.
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Comments
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I had a similar problem that was caused by a loose headset. Went away once I tightened it up. Like with your bike it was pretty random and I couldn't make it happen on purpose.0
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Thats reassuring, thanks - all I can guess is that it happens when the vibration from the rotor just happens to be at a certain frequency which causes the fork to resonate. Hopefully with the headset tighter it will be sorted.
Interestingly, not only was there a little play in the headset but the two pinch bolts on the side of the stem were nowhere near the 6Nm torque that the stem has written on it. Not impressed with the PDI that LBS did on the bike...!0 -
I think certain speeds, road surfaces and degree of braking excite the vibration.0
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Looks like it may be sorted. Tightened the headset a bit and 20 miles today with no juddering at all. Fingers crossed that will be the end of it.
I couldnt consciously feel a difference riding but also felt more confident/stable standing up pedalling on the bike today too - it may be imperceptible but there was something about the feel that was more solid and reassuring today.0
