Front carbon fork rumbling noise - what could it be?

[DCLane]

The Principia RSLe this morning has developed a low rumbling noise from the forks when going over anything but perfectly smooth tarmac.

It's almost as if something's resonating inside it - and is unnerving.

Any thoughts?

 

[Hacienda71]

Loose headset. Re-grease and tighten. See if that makes a difference.

 

[mynydd]

Sounds like wheel bearings to me....... could the grease have washed away?

 

[DCLane]

Sounds like wheel bearings to me....... could the grease have washed away?

Could've done - I last used the bike during filming for The Club. It was wet most of the day. I'll try a different front wheel.

Loose headset. Re-grease and tighten. See if that makes a difference.

Thanks: I'll have a go with this.

 

[Yellow Saddle]

The Principia RSLe this morning has developed a low rumbling noise from the forks when going over anything but perfectly smooth tarmac.

It's almost as if something's resonating inside it - and is unnerving.

Any thoughts?

View attachment 342592

Both possible causes have already been mentioned. Here's how to diagnose them.

1) To diagnose a loose headset. Stand next to the bike holding the bars. Now drop your but onto the top tube and apply weight i.e. sit. Pull the front brake hard and rock the bike forwards and backwards. Look for a mechanical clack clack feel rather than noise, but try and distinguish between brake flex and a little bit of noise/feel as the brakes move forward and backward and that of a loose headset bearing. Also, if you pick the bike up by its neck (stem) and bash it down, you'll feel a loose headset via feedback. To diagnose poor headset bearings, grab the bike by the neck, pick it up and move your fist left and right to "steer". The bearings will give you smooth or rough feedback depending on their condition. If at first you don't feel anything, compare a few bikes. Soon you'll settle on a baseline and know the condition of yours.

2) To diagnose poor front wheel bearings. Put the bike on a stand or have someone hold it off the floor. Spin the front wheel and put your ear on the top tube. A rumbling bearing will talk to you and say either: rrrrreplace me or, ssshhhhhh leave me alone.

Bikes can talk. My money is on the headset.

 

[cyberknight]

Both possible causes have already been mentioned. Here's how to diagnose them.

1) To diagnose a loose headset. Stand next to the bike holding the bars. Now drop your but onto the top tube and apply weight i.e. sit. Pull the front brake hard and rock the bike forwards and backwards. Look for a mechanical clack clack feel rather than noise, but try and distinguish between brake flex and a little bit of noise/feel as the brakes move forward and backward and that of a loose headset bearing. Also, if you pick the bike up by its neck (stem) and bash it down, you'll feel a loose headset via feedback. To diagnose poor headset bearings, grab the bike by the neck, pick it up and move your fist left and right to "steer". The bearings will give you smooth or rough feedback depending on their condition. If at first you don't feel anything, compare a few bikes. Soon you'll settle on a baseline and know the condition of yours.

2) To diagnose poor front wheel bearings. Put the bike on a stand or have someone hold it off the floor. Spin the front wheel and put your ear on the top tube. A rumbling bearing will talk to you and say either: rrrrreplace me or, ssshhhhhh leave me alone.

Bikes can talk. My money is on the headset.

Mines saying why havent you ridden me for 2 days ?

 

[Levo-Lon]

I'd pop the wheel out and spin it while holding the skewer..you will feel it rumbling..

I'm sure YS post is spot on for eliminating

 

[Yellow Saddle]

I'd pop the wheel out and spin it while holding the skewer..you will feel it rumbling..

I'm sure YS post is spot on for eliminating

That's my preferred method as well but not many people know how to do it and the description for holding the wheel with one hand and spinning it with the other is looooong.

Also, about 30% of my students back in the days just cannot distinguish between a rumbling bearing and a good one. I used to tell them they just didn't have a good baseline reference but secretly I believe some people are just so mechanically unsympathetic that they'll never get the hang of it.

 

[Yellow Saddle]

Mines saying why havent you ridden me for 2 days ?

It is better NOT to bond with your bike that well. Some of them even become jealous when you fiddle with another bike's bottom bracket and we don't want that, do we?

 

[DCLane]

Thanks both

@mynydd - tried a different front wheel. Still the same noise but thanks for helping me find another wheel that could do with new bearings (that's 5 this week).

@Hacienda71 - I adjusted it. Still the same noise. Another job on the 'to do' list which'll be to learn how to grease a headset.

 

[DCLane]

Further edit: I've remembered the LBS fitted new headset bearings in December. That's less than 200 miles ago.

 

[lutonloony]

It's probably the bike complaining about the cross chaining

 

[davidphilips]

as yellow saddle said Bikes can talk. My money is on the headset. most likely cause of noise even if a new head set was fitted and theres a chance who ever fitted the new headset reused part of the old headset . only other thing i would say is a very unlikely cause but without hearing it just take a good look around forks and even frame in case or a crack dont want to scare you but just check any way.