I hope someone can help me out with something weird with a relatively new bike I have. I bought it from a LBS and have done about 500 km on it already.
Fairly early on, it developed a very strange sound, like a rumbling or crunching sound in the driveline. I sent the bike back to the shop and 3 mechanics took a look at the bike. 1 decided to retighten the cassette, 1 retightens the bottom bracket and 1 says the pedal housing is cracked and replaces the pedals. Ok, so I took the bike back and on the 1st ride, notice the noise was still there. Since the LBS was a bit ways away, I deicided to just live with the problem for the time being since they have already checked the major components. But for the past few days, the sound seem to have worsten quite a lot (gotten louder) so I decided to do some of my own checking and this was what I found:
There are 4 cracks are almost symetrical around the middle chainring. About 1-2 teeth difference. The pictured one is the largest of the 4. I'm not really sure are they part of the chainring design or not because these are newer ones with funny patterns stamped into them.
Also, not really sure about this too but I don't think its normal. When the chain sits on the chainring, I can see daylight through the teeth almost around the chainring. The last time I saw this on me old bike, the chain was really worn. But this bike only has 500 km done on all these components. I only noticed this when I took the chainguard off.
Comments and advice much appreciated.