farmerjg

This is a new to me Madone 5.9. I've ridden it all summer and I've started to pick up this crunching sound. The guy told me he replaced the BB last summer, so I guess I thought/hoped it was fine.

You can hear it when my right foot comes right over top dead center

I'd love to hear your thoughts, though it looks like the world of aftermarket BB90's is in my future.

dieselgoat

You have my sympathy trying to track down a creak. Most people immediately point to the bottom bracket and the majority of the time it is not. Do some searches on here for creaks and there are lots of checklists of stuff you should try before changing the bottom bracket. I doubt that it needs to be replaced after just one year. Don't be surprised if it's something entirely different and it could be coming from somewhere you would never suspect.

Brocephus

I'd say that's a hella lot more than your typical, tiny, mystery-creak ! Dieselgoat makes a good point about the BB being on everyone's short list, then not being the actual problem, but that does sound like it's in the BB, or the crank.
But, it also had kind of a hollow, woody sound that made me suspect a crack in the carbon frame somewhere. You check that closely already?
How does it sound when you spin the cranks, with no one on the bike? How old is the bike ? (I'm wondering how old it was when the original owner replaced the BB.)

Unca_Sam

I'm pretty sure it's on Sheldon Brown's website as a tip for diagnosing creaks and BB problems. Put your bike in a stand so you can turn the cranks; put your ear on the 'horn' of your saddle; turn the cranks and listen. The bike frame will amplify sounds in the BB shell and transmit them directly to your ear. If the sound is a crunchy rumble, it's likely your bearings, if it's smoother steel on steel sound, your BB is probably fine, and it's time to look elsewhere.

I can't do this, but you can. Isolate the components of the drivetrain (and maybe marvel at the ingenuity) and test them one by one. Narrow it all down and you'll get your noise, then you can find a solution.

Happy hunting!

sgnl2nz

Last time I had what I was convinced was a BB creak, it turned out that I re-installed the wrong size spacer between the rear hub and cassette after servicing. There was just enough play to transmit to the cranks and through the frame.

farmerjg

I have looked over the entirety of the frame. If the frame itself is cracked then it's somewhere not visible to me (i.e.-somewhere recessed or behind components). Additionally, the thing rode fine with no noise for quite a while. And there was no drop/laying down event that precipitated the noise. It's just become gradually louder and more frequent.

Spinning cranks with the bike unloaded, it will still mostly make the noise, but it's not as harsh. And sometimes (but with no consistency) I can hop on the bike and it will be quiet for the first mile or so. And then most other times I'll get on and it's immediately present. But I'm almost to the point now where it's like 9/10 noisy.

Age? Great question. I don't think I ever got a year from the guy. But the 5.9's appear to have the capability to be at least 9 years old now. Unsatisfactory answer, I apologize.

And when did he replace the BB. You know, that's a good question. He had only said that he had done it recently. But I know I think things are "recent," but when I really think about it it'll be something where I only had one kid at the time which means it was least five years ago. Getting old sucks.

Thank you for these tips. It looks like I have my weekend activities all lined up now!

Brocephus

I got curious, and just rummaged through the Trek archives, and the closest color match I could find was from 2011.......
https://archive.trekbikes.com/us/en/...done59/details
(though I see from your video, the graphics on your fork are grey, but here they're blue. But, the other graphics looked right, and no other 5.9's I saw had that Lake Placid blue color.)
Anyway, I was wondering if the first BB replacement may have been real early, and indicative of a problem with them, but it looks like he got several years out of it.
I would pull the BB, and see how it spins and feels, in-hand. If you're getting grinding while the bike is unloaded, then if it's the BB, you should feel it when it's in-hand. Assuming you have the tools, that's a cheap and easy test, that you're probably gonna have to do anyway.

farmerjg

Finally got some time today.

This is a chainless free wheel. Honestly, I don't know the difference between good and bad, but this doesn't sound terrible.

Then there's this, which I suspect is slightly less good. I'm pushing in/out in parallel with the BB. If you look closely when I move the view overhead you can see the pedal shifting a little.

ridelikeaturtle

Am I the only one that views a BB as a "consumable"?

Replace it, now - simple. Eliminate it as a problem.

If the noise persists, it's something else; but you've created "ground zero" for your BB (mark it down in your "consumable" diary).

My experience with "it's been done recently" means anywhere from 2 to >5yrs ago. People's perceptions can be all over the shop.

terrymorse 

That clicking when you move the left crank — sure sounds like a loose connection to the spindle.

Remove the left crank, clean and inspect the spindle-to-crank interface, reinstall and torque the binding bolts to spec.

If you're lucky, that's all it is.