please help diagnose...
 

without the chain attached, spinning crank makes a noise like there is sand in between something and it makes crunchy noises...very very subtle noise. i clean my chain ever 100 miles or so and wipe down bike after every ride. i just noticed this for the first time and it worries me. its an AL frame too so its hard to pinpoint the exact place. only thing i know is whenever i turn the crank i can hear it. with the chain on you could even tell.

is it possible small debris got in crank some how or frame has problem? i didnt see any fatigue in frame or cracks. i cleaned in between the gap where BB goes though frame (sorry dont know term) but still noise...

Since, as you describe it only the crank is turning when you hear the noise, the only place it could be is within the bottom bracket bearing and/or the seals. If dirt and sand only got as far as the seals, you're fine for now, but it'll migrate farther and get into your bearings and cause excess wear soon enough. If it's already in the bearings, you want to get them serviced before riding much more.

Either way it sounds like you need the BB serviced soon if not immediately. You can have a shop do the job, or can look up tutorials specific to your type of bottom bracket and do it yourself. If you act now there's a good chance that no parts will be needed, just some cleaning and regreasing.

thanks...that sounds bad. i've had this caad9 since nov 2010. ride it only during decent weather conditions. rode about 1500 miles so far...very casual rides avoiding dusty roads/ wet. this sucks. my other bike BD bike ..over 4 years, rode in all kinds of conditions and i've never experienced a noise with that thing...

i wouldve thought i pay a little more money so it would last longer..

High end bikes are a bit like high end cars. More money often means a more finicky machine. An engine out of a standard Ford or Chevy can go 100,000 miles without any service besides oil changes, and maybe spark plugs (possibly a timing belt at 60,000 miles) Meanwhile a race car engine built by the same folks needs to be torn down and rebuilt every few thousand miles.

Basic utility bikes are built to go for long times without service because it's expected that their owners won't do any anyway. Better bikes are built to more precise standards and will last longer but may require more owner maintenance, but you should have done better than you did.\

It's very possible that all is in face OK, and the noise you're hearing is only dirt at the outer edge of the seal, which is OK. And it's also possible that your cleaning process is pushing dirt in causing the problem. Since you can't tell bring it to the shop, let them check it, and if the bearing is contaminated, ask them if you should change the way you clean the area.