Bicycle Mechanics - Can anyone please help diagnose this noise?

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Bob Ross
10-03-07, 12:54 PM
I realize attempting to diagnose a noise in an internet forum is an exercise in futility (...unless this message board allows .mp3 attachments? Hmmm...) but bear with me please. Perhaps this will be obvious to someone.

Hardware: Frame & fork are 22-year-old Bridgestone 600 (lugged CroMoly 4130). Handlebars are new Deda 215, stem is new Nitto Technomic, bartape is new fizik BarGel or Specialized BarPhat or some other such semi-compliant non-cork substance (I didn't install the bars or wrap them so I don't know for certain). Headset is original 1" threaded, brake levers are original DiaCompte.

Symptoms: When I am riding in the drops -- and only when I'm in the drops, it never makes this sound when I'm riding on the hoods or on the tops -- there is a CREAKING noise that comes from somewhere around my hands. It seems like I can exacerbate this noise by torquing my hand up & down in the vertical plane (i.e., parallel to the direction the bars are facing...which, since I'm in the drops, means essentially forward & back in relation to the direction I'm travelling). It originally was only audible on the right side, but very recently I've started to notice it (albeit to a lesser extent) on the left also. It sounds like a cross between what a loose squeaky floorboard would sound like when you walked across it, and what a steel I-beam would sound like moments before it collapsed due to the weight of King Kong sitting on top of the building (...if it were a really tiny building and a really tiny King Kong). Call it a squeak, or a creak, but more of a snap-crackle-and/or-pop...not loud, mostly concentrated in the midrange (1.2-3kHz).

Ignorant guesses: Bar tape shifting along the bar? Brake lever not screwed down tight enough? Stress-crack in the aluminum handlebar?

Any suggestions would be greatly appreciated. Thanks


CharlesC
10-03-07, 01:21 PM
Since you apparently didn't have the noise with the original bar and stem it would seem either the stem is creaking in the steering tube or in the new bar is creaking in the new stem. I'd replace them with the old parts, one at a time, to isolate the noise.

ultraman6970
10-03-07, 01:42 PM
Wonder if the brake levers clamps are tight!

just my 1%


HillRider
10-03-07, 06:58 PM
Most likely source: the bars creaking in the stem clamp. The Nitto has a circular, one bolt clamp and these are difficult to keep quiet. I had this problem on several bikes and it took a lot of greasing to quiet them down. It was much worse with sleeved bars but one-piece bars aren't immune either. A removable faceplate stem is less likely to have this noise problem.

Second possibility: The quill creaking inside the steerer tube. Cure: pull stem and grease the quill heavily.