Help me track down a noise!

Hi all,

I’m reaching wit’s end tracking down a noise on my ENVE Mog, and looking to this group for any help/guidance.

My Mog is about 10 months old. It is my favorite bike ever. It’s set up with a full Red XPLR groupset with threadmount power meter crankset. Chris King ceramic T47i BB. Roval Terra seatpost with S-work Power Mirror saddle. ENVE in-route aero stem with SES AR handlebars. CeramicSpeed SLT headset bearings. It’s been mostly ridden with Reserve 40|44 GR wheels sporting 2.1” Thunder Burts, but I’ve also used some Zipp 303 Firecrests with a couple different tires (currently Caracal Race 45’s).

In late July I flew with the bike for the first time to a race, packed in a Scicon Aerocomfort case. Upon unpacking the bike, it had clearly been knocked around enough in transit that the stem was slightly malrotated on the steerer tube. I loosened the stem and topcap to realign things, inspected it as well as I could to make sure nothing looked damaged, and torqued it all back to spec. I rode the bike throughout that weekend, including the race (The Last Best Ride), which is a mountainous 90-ish mile gravel race with a healthy mix of road, tame gravel, gnarly gravel, and fire roads. Near the end of that, as I was coming back into town on the roads toward the finish, I began to notice a new noise coming from the bike. Initially I chalked it up a dirty/dusty drivetrain and didn’t think much of it. But … despite flying home, cleaning the bike thoroughly, and now troubleshooting every damn thing I can think of … the noise persists. And I am losing my mind …

To be honest, I have no idea if the above travel and twisted stem/steerer has anything to do with it, but it’s the only thing that I can think of that’s “changed” with this bike over my 10 months of ownership. I am certain that it didn’t exist before this race, and had probably ridden the bike somewhere around 1250 miles up to that point.

The noise is a subtle one that I’ll describe as a “buzz” or maybe a slight “rattle”. It occurs intermittently, and only on pavement that is somewhat “textured”. Totally smooth pavement is fine, and rougher gravel/bumps seem fine as well. So it’s almost like a certain vibration or resonance has to be hit in order for the sound to appear. Generally, the sound will continue for a few seconds until the pavement contour changes. Shifting my weight on the bike doesn’t necessarily stop it. Braking does. It seems to occur more consistently running the Reserve/TB combo than my other wheels (though it happens with both), which I’ve chalked up to the knobbier tires that I’m guessing somehow contribute to the vibration/resonance occurring more regularly. Some rides it occurs barely at all, other rides it happens on and off over the whole duration. I have not figured out any rhyme or reason for that intermittency. It happens both during pedaling and coasting, and is not rhythmic with my cadence, so does not appear to be drivetrain related. It can happen either while seated or while standing, so does not seem to be saddle/seatpost related.

To my ears, it seems to be coming from the front half of the bike, but having hunted down noises in the past on other bikes, I know accurately hearing where something is coming from can be tough, if not impossible. Here are the various other troubleshooting steps I’ve taken, none of which have resolved it or clarified its source:

  • Touching different parts of the bike while the sound is occurring to see if I can feel where it’s coming from (or get it to stop). This includes all the parts of the frame/fork I can safely reach while riding, the bottles/cages, the storage hatch cover/latch, the out front computer/light mount, all parts of the stem/handlebar and levers.
  • There isn’t sufficient slack in the hoses to pull the stem all the way off the steerer without also completely loosening the calipers from their mounts, so I haven’t gone to that extent yet. But I’ve removed the topcap and loosened the stem to slide it up as far as I can get it, and then inspected what I can see of the steerer. Everything looks fine (no cracks, no abrasions, no rings). Headset bearings appear properly seated. I’ve then re-torqued everything to spec again. The headset has remained tight, and I never noticed any play in it prior to travel either.
  • Removed the stem faceplate, inspected the bars and stem interface. Reinstalled and torqued to spec.
  • Tried different bottle cages, different bottles, and even no bottle cages/bottles.
  • Took everything out of the downtube storage. Made sure the rear brake hose is well-secured within the frame (there’s a velcro strap thing inside the storage compartment).
  • Removed, cleaned, greased, and reinstalled every single mounting bolt on the frame and fork legs.
  • Removed, cleaned, and reinstalled the chainstay protector. Also temporarily wrapped electrical tape around the chainstay protector to make absolutely sure it wasn’t rattling. It wasn’t.
  • Removed the cranks. Cleaned the spindle spacers. Cleaned and regreased the spindle. Reinstalled and torqued to spec.
  • Tried a different set of (new) pedals. Tried new cleats.
  • Swapped in a different seatpost/saddle.
  • Chain has been thoroughly cleaned, freshly waxed.

Despite ALL of this, the sound still happens. I am honestly hesitant to take it into the shop, partly because I’m afraid they’ll think I’m nuts, but mostly because I don’t even have a consistent way to make the noise occur!! My fear is they’ll ride it around their parking lot a few times, say “sounds fine to me”, and hand it back. And short of asking them to strip the whole damn thing down and rebuild it from scratch … I don’t even know what else I’d ask them to do!

So … what am I missing here?

Do you know how the Mog is formed? I ask because I’m wondering if it’s a molding bladder (or part of) that’s stuck in the frame.

The other thing that springs to mind is the brake pads. Do you happen to be running pads with cooling fins on them?

Wish I could get my hands on the bike - I love solving noise issues! Probably because a noisy bike is the single most frustrating and annoying thing for me as a rider. Noise wrecks a ride for me.

Brake pads is a good thought, and one that actually occurred to me while laying in bed thinking more about all this last night!

I use MTX Red pads … so no, no cooling fins. However, they are MTX’s RL160’s and not their RL165’s … so they’re slightly different shape than stock SRAM pads. MTX claims they work the same, but maybe something about the shape difference allows them to rattle after reaching a certain amount of wear? The sound did seem to start during that race after a quite long (12ish miles?) descent with a lot of hard braking. I’ve looked at the pads and they don’t look very worn … but maybe that’s it?

I’ve still got the stock SRAM pads somewhere, so maybe next step is to swap those back in and see what happens.

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Brake pads sounds possible and would certainly give a resonant buzz and stop if you brake hard.

the other possibility is that brake hoses are vibrating against something internally. Different hose length and foam cable sleeves usually solve those issues.

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Brake hose rattling was my thoughts based on every you’ve tried.

I’d guess the frame was built up with foam tubing on the rear brake hose through the frame. If not that it could be source.

Or the hoses as they go through the bars. I’ve had that before on a SL7, with Roval bars, where the buzz was not apparent on my typical test route but on smoother tarmac I could hear it.

Or possibly the front brake hose vibrating against the fork above where it enters the steerer tube hole.

The rear hose is covered with foam tubing and secured inside the down tube storage hatch with a little Velcro flap that’s glued or bonded somehow to the frame. So I don’t think it’s that.

The front brake hose rattling somehow or one of the hoses rattling inside the handlebar is, I suppose, possible. But man … seems like a real PITA to mess with that without being absolutely sure it’s the cause. I guess I’d maybe I go to that extent if the different brake pad thing doesn’t work out.

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Well, I’ll be damned. Seems like swapping the front brake pads to the stock SRAM pads solved it!

I find it odd though. I’ve been running those MTX pads basically right from the start of ownership, and they caused no issues for over 1000mi. And they definitely don’t look significantly worn … so why it would rattle now is a mystery :person_shrugging:

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