Drivetrain Noise..HELP

sohoscot

I recently built up a Carbon Fiber bike...all 105/Ultegra.

ALL Parts are new 105 compact Crank, Ultegra chain, 105 rear der.

There is a grumbling sound while in Large front & small rear & 2 or 3 gears up with still large front...

This is not typical clicking or rubbing....I can only compare it to when your driving & you get to far over & hit the "rumble" strips......or droaning sound....deep vibration type sound.

I have not ridden it yet...so I don't know if this noise is just vibration resonating through the Carbon frame while in the stand.....or if it's a whole other issue. But it sounds like it's more than just vibration.

Please let me know if you have had similar issues..and what it might be.

Thanks

ScottChapman

Well, I think you need to identify where the noise is coming from. Is it coming from the front or rear deralieur?

To me it sounds like a cross-chaining issue, which usually just requires a mire adjustment of the stop screws on your front deralieur.

If there is good clearance there, you might consider lubing your chain?

dhk2

Probably the normal rumbling sound that comes from the small cogs, particularly when under heavy RD tension from the big ring. Chains don't like to be pulled around the small cogs; you can see the chain jumping a bit over the teeth if you pedal slowly.

Also, did you clean the preservative grease from your new chain and relube it? Proper chain lube should reduce the noise a bit, as well as some break-in miles on the chain and cogs.

If you take the bike out on the road and still notice or feel the noise, then I'd search for other causes. Otherwise, ride and enjoy.

OldGoat

Excess chain length can cause the upper rear der pulley wheel to rub against the chain when in the small cogs in the rear. Similarly, incorrect adjustment of the rear der's "B" screw can cause the upper pulley to contact the rear cogset. Either condition could cause a noise such as you've described.

Dr_hush1417

I recently built up a Carbon Fiber bike...all 105/Ultegra.

ALL Parts are new 105 compact Crank, Ultegra chain, 105 rear der.

There is a grumbling sound while in Large front & small rear & 2 or 3 gears up with still large front...

This is not typical clicking or rubbing....I can only compare it to when your driving & you get to far over & hit the "rumble" strips......or droaning sound....deep vibration type sound.

I think you are having the same exact problem I had when I got my new bike about 6 months ago... what is probably happening (especially if you got a 10-speed and didn't have previously) is that the cassette is too narrow on your free-hub, and you need an extra spacerto make it not wobble back and fourth. My problem was exactly the same, on the same gears only.

Try taking off your rear wheel and holding the cassette, then push it back and fourth on your hub, in other words, if it were on the bike, push and pull it left to right. If you feel even the slightest movement back and fourth, thats you problem.

Hope that helps:)

sohoscot

First of all...thanks to everyone for their advice...greatly appreciated !!

....Figured out the source of the noise.... The frame bracket that holds the front derailleur was loose...!! So at high RPM the resonation vibrated the bracket..!!

You would think paying $900 for a frameset...they would have all the bolts tightened !!!!!!!!

S.

Pkumble

I recently built up a Carbon Fiber bike...all 105/Ultegra.

ALL Parts are new 105 compact Crank, Ultegra chain, 105 rear der.

There is a grumbling sound while in Large front & small rear & 2 or 3 gears up with still large front...

This is not typical clicking or rubbing....I can only compare it to when your driving & you get to far over & hit the "rumble" strips......or droaning sound....deep vibration type sound.

I have not ridden it yet...so I don't know if this noise is just vibration resonating through the Carbon frame while in the stand.....or if it's a whole other issue. But it sounds like it's more than just vibration.

Please let me know if you have had similar issues..and what it might be.

Thanks

What did you eat for lunch?

King Schlooge

I am glad your solution turned out to be a simple one. I would think it would not be unusual that when you buy a new frameset only with a clamp-on type front derailleur bracket, they may leave it loose so that you can fine tune the height of the bracket and front derailleur depending on what largest chainring your crankset is equipped with and then cinch it down.