Hello,

I am concerned about a noise coming from the BB86 Bottom bracket on my Giant TCR Advanced SL. Please watch the video on the link below which explains pretty much everything.

The sound started after a minor crash on February earlier this year. The bike did not touch the pavement but fell on top of other bikes within a pile up at a race. It sounds like a bearing is shut or there is sand in the bottom bracket. I am about to head into a group ride and would like some advice or peace of mind before heading out.

I really hope and I really don't think it has to do anything with the frame. It is unscratched and unharmed (aesthetically).

Thanks,
Luis

Bottom bracket noise - YouTube

Ok.. there is a very big chance that the noise is coming from gunk and junk in the chain. Like debris in the chain lube... however it doesn't matter how many times I clean the chain it still does it.

Pull the chain off the chainrings and lay it on the BB shell. Then, turn the crank without the chain to determine if it's in the BB or is chain related. If it's in the BB, remove the cranks and turn each bearing by hand. If they turn smoothly, the bearings are fine. If they don't, that's your problem. Replace them. If it's chain related, see if you can narrow it down to specific links. Does the RD "hop" periodically? You might have a link that's distorted or has been twisted so that it doesn't move freely.

Hmmm-sounds like there is sand somewhere? I may have just been experiencing similar to what you are. Running full native everything Ultegra 6800. Did a ride in the rain last Thurs morning and it's been noisy since. Definitely felt sandy grit on my chainrings with my fingers. With the chain off BB feels fine and runs smooth as can be.

Cleaned drivetrain twice with my chain cleaner - first ran it using with Park solvent and then a second time with warm water and Dawn dishwashing liquid; thoroughly cleaning out chain machine each time. Also wiped down chainrings and cleaned cassette with gear floss. I let chain dry overnight and then relubed. Seems to be better now; hopefully will improve after riding and working the lube back into links. The problem was definitely more pronounced and louder in certain gear combos - 50 x 23 and 25 (11-28 cassette) - there would be some extra cross chaining stresses there.

My hunch is that with the tighter spacings and tolerances with 11speed, the system is more sensitive to sand and grit then in the past - but I'm not a mechanical engineer, so I dunno?

Sometimes BB are installed too tightly so the cups impinge on the bearings. If your BB doesn't spin freely with the chain removed this might be the case. Can't tell from the video.