When I am in the biggest ring in back and the small ring in front I get an annoying grinding sound from the front ring. The chain is not rubbing the front derailleur and the back is adjusted so it shifts cleanly. It looks though like the front and the back are out of alignment slightly so the chain comes off the front at an angle. The chain also jumps and twitches a little like it’s catching and grinding against the front ring because of the angle.
Is something out of adjustment? Or do I have an unrecognized compatibility issue? I believe the front and back are compatible but it’s possible in switching wheels and cassettes between bikes something got out of whack.
It’s not your chain line unless you have another very serious issue. What you describe (a 34/25 combination) should pull the chain away from the 50, not into it. A 10 speed compact system should not produce cross chaining rub until you are on the last 2 cassette sprockets opposite the front chain ring. On a standard setup you might not even get cross chaining rub even then.
So what to look for? You say it is not the FD, but that is almost always the cause. The cage gets bent and the backend of it rubs the chain. It can be from side to side on up and down. Bent either way will cause the noise.
After that it is rather tough to suggest a problem over the internet. I have never seen, but heard of the chain ring bolts coming loose and causing problems. Depending on the brand and some other conditions that could get in the way of the chain. I’ve also seen water bottle cages get in the way of the chain, but you have to screw up pretty bad to pull that off.
Best thing to do is turn the bike upside down and turn the pedals slowly and see what it rubbing. Good luck
+1, and also check to make sure the big chairing isn’t rubbing on the derailleur cage. sometimes the der. is mounted a little too low and there will be contact.
May be due to a worn out chain or inner ring. I find a brand new chain often solves these issues. At least try cleaning and lubing your chain.
Maybe slightly mismatched groupset? My Cervelo used to have FSA chainrings and they were quite noisy (grinding sort of sound) compared to a full shimano groupset on another bike. I changed the cervelo’s to a shimano chainring and immediately noticed it was smoother and quieter.
I have never seen, but heard of the chain ring bolts coming loose and causing problems.
Exactly what I had to fix last night. Some really funky clicking and grinding noises popped up during IM Boulder. Hopped off a few times to check and for the life of me (and some other curious racers), could not figure it out. Finally got my bike back from Tribike transport over the weekend and found the bolts were WAY loose. Surprised I didn’t notice it during the IM. Tightened and all is good.
I had a weird clicking noise on my road bike and it turned out I adjusted my chain catcher too close to where it was making contact with the back of the of only 1 chainring bolt (odd it wasn’t all of them though). Couldn’t hear it coasting obviously or pedaling backwards (since the freehub ratcheting noise was louder).
Also, if I don’t have my front derailleur setup right (not the right tension) one of the trim settings wouldn’t work properly (either the small chainring trim setting or the big trim setting). That would make an odd grinding noise in that trim setting that wasn’t right even though there wasn’t any contact being made with the chain. Only remedy was to start over and get that FD adjusted correctly (or as best I could…not have a properly functioning barrel adjuster made it hard to get the tension just right for my road bike).
I’ve had this before too. For those asking if it is rubbing the big ring, I’m pretty sure the OP means that the chain is angling -in- towards the frame to the biggest cog on the rear wheel. I think jut some frames and BB combinations cause a chainline that is slightly off, causing it to be like cross chaining when in your easiest gear (small ring in front, big ring in back).