dkrajisnik

I can hear a dull clicking sound when I ride. Lower pitched than, say, a piece of rock being kicked up by the front wheel and hitting the (aluminum) frame. Each click is almost like a creaking but of a much shorter duration (maybe a few milliseconds at most). The clicks come in irregular groups. This started a few days ago and it happens every few minutes during the ride, then it stops for a little while and starts back up again. The problem only occurs when pedaling.

It seems to be coming from somewhere around the bottom bracket or drivetrain. I put the bike on my stand yesterday, tried out a few gear combos I most commonly use but I couldn't reproduce it.

For now, it doesn't affect the ride.

Any ideas what I should look into?

Bike is an '07 Specialized Allez Double.

FastJake

When pedaling or when coasting? Both? That will narrow it down.

Clicking/creaking/etc can be hard to pin down. It could be your bottom bracket/crankset, your pedals, wheels, or something as simple as shoelaces clicking as you pedal.

aixaix 

Also check your saddle & seat post clamp, bars & stem. Make sure the bolts are tight.

dkrajisnik

When pedaling only! Actually, right after I stop pedaling there may be 1 click or so but that could just be my imagination.

How could I forget to mention that?!

It's not shoelaces. I've had that problem before and it was the first thing I checked.

dsbrantjr

dk: You might try borrowing a different set of pedals and swapping them out. It might at least help narrow down the source of the noise. Also make sure you are not brushing the end of the front derailleur cable with your feet or crank

FBinNY 

A common cause of this is one pedal being just a hair loose on the crank arm, possibly with dirt under the face. It takes a minute to remove, clean the threads and face, grease and remount.

The other easy cause is loose chainring bolts allowing the chainrings to shift a hair under load. use the hex or Torx key and give each bolt a tug and see of ti moves.

If either of the above cures it, you've dodged a ton of PIA diagnostics because everthing else is more complicated, Starting with loose crank/spindle fit, loose BB, spindle play in External BB bearings, BB unit or bearings moving in the BB shell, dry chain, creaking as it settles on the chainring (common with worn chainrings), or any number of things having nothing to do with the BB, including rear hub axle face moving in the dropout, saddle/rails/post, and on and on.

Start with the simple, and use some diagnostics based on timing, frequency, and any other factors which might yield a hint, before you start taking everything apart.