Noises from new BBSHD

[huffinandpuffin]

After endless tear downs of old BBS02 to get rid of a clicking sound I decided to get a new BBSHD. Noise persists (doh!). Noticed the drive cover was up against the chainstay; added a spacer. Even worse. The lock nut is properly torqued, as are new crank arms. The sound is definitely in sync with pedaling.

Could it be from the shaft housing rubbing against the inside of BB shell? Perhaps a really thin shim and lots of grease? Any suggestions welcome.

 

[amberwolf]

If it's exactly the same noise at exactly the same point in the pedal travel circle, then it's probably not in the drive (since changing the drive out to a different system should eliminate that, and the chance of it being identical is small), and indicates some other mechanical issue with the bike itself. Could even be a cracked frame that is opening/closing the crack with pedal pressure.

If it's not exactly the same noise, and/or is not at the same point in the circle, it could be in the drive.

Some kinds of noises (clicks, etc) can indicate bearing problems; I had a pedal bike with cartridge bearings in the BB (like what is used in these drives) that clicked on every downstroke on one side, and that bearing had a cracked outer race.

Do you have any way to monitor sounds in different places on the bike to hear exactly where it is coming from? For instance, start a recording app on the phone and tape the phone to the bike in different places. (or if you have one of those remote lavalier mikes, tape it to the bike instead).

 

[huffinandpuffin]

The weird part is that it’s intermittent. It can be totally absent then just start again. Really loud on a climb then silent on another climb. Loud on flats then silent.

 

[amberwolf]

Most of the problems that cause noises would only be intermittent under different conditions. For instance, if one ride where the noise happens, you have to pedal harder than another ride where it doesn't, or vice-versa.

Or different temperatures, so that say, it happens when cold cuz the grease congeals and the balls in a bearing (if not in a carrier) all end up in the wrong place during rotation to carry the load, but when warm the grease flows and the balls move evenly, etc.

If you can find the differences between when it happens and when it doesn't, you can narrow down the cause.

Finding the exact spot the noise comes from can also do that.

 

[huffinandpuffin]

We can be riding along all quiet and the noise will just start. It’s not related to temperature or anything like that.

 

[amberwolf]

Then your best bet is to locate the spot the sound is coming from; more difficult if it's intermittent, but stil possilbe.

My bet is a bearing, but tehre are several bearings in there, and the gears, and the chance of it being a cracked housing or frame, etc.

If you're using the same pedals it could even be inside those.

Heck, while unlikely to be in sync with the pedalling, if the noise isn't actually from the BB area it could even be an escaped nipple or other debris inside a rim, or a loose nipple on one of the spokes allowing it to tension and detension.