Bought a new Redline 925 a few weeks ago.

Have noticed a noise when pedalling (not the normal ratcheting sound when coasting). Is a little "clunk" or knocking sound several times for each turn of the crank. I can't count accurately while riding, but seems like 5 to 6 clunks for each turn of the crank. My guess would be that's 2 for each turn of the rear wheel.

The shop where I bought it said it might need lube/cleaning, so they did that for me last week - but the noise is still there.

It's not so loud that I can hear it all the time (wind or traffic noise usually masks it), and I don't know if it's something to be concerned about.

One possible fix may be for me to just flip the rear wheel around and start riding as a fixed gear

Opinions please? Any guesses about source of noise, and what (if anything) else should be done about it?