More than creaking
 

Videos of the issue

Any advice appreciated. We are about $800 into service and parts replacement trying to eliminate this unenjoyable noise.

It starts around mile 4 and gets progressively worse as the miles add up. Before the bike shop, pedals and seat tubes regreased. Bike shop replaced both bottom brackets, the essentric the chains, and just replaced the rear crankset. They cleaned the headset. They thought maybe the PAS disc was rubbing on the bottom bracket, I removed and the noise continues.

It's when I'm pedaling in front. If she comes off the pedals the sound goes away. I've also swapped out the pedals with another bike with no joy.

I feel your pain.

That sounds like rubbing more than creaking. I don’t have any great advice, but some places I finally found loud noises after spending lots of time not finding them:

1) Terry Butterfly saddle rails. Apparently, that’s a part that can fail and it’s really loud right before it fails. The noise went away when the stoker stopped pedaling as she was no longer stressing the part.

2) Tamer suspension seat post: They get loud when they need oiling and even louder when the pivot holes get enlarged.

3) Spinergy rear wheel: Spinergy makes some high maintenance wheels. First the spokes all loosened up which made a grinding sound and later the hub developed a loud freak. Usually after a few miles of riding in warm weather. Turns out the hub needs to be disassembled periodically and oiled. That’s a nice fairer.

Check the saddle clamp and the saddle itself would be where I start.

If you have disc brakes, check if the pads are seated properly and carefully check your wheel bearings. Worn bearings or loose cups or quick release can cause the wheel to wobble with pedal cadence causing the rotor to collide with the caliper or the caliper mount.

Does standing up and pedaling out of the saddle affect the noise?

FWIW I don't think this sound is saddle related. It has the frequency of a rotational part. That is either the wheels or the drivetrain. Are the tires kept at max pressure or something lower? There is more bulge in sidewalls than when the tire is inflated to max pressure. If the fenders are close clearance the scraping that results would not be unlike what is heard in the video. The sound begins at 4 miles ... so something is heating up. In it's cold, contracted state, it is not a problem. It might be a brake caliper. Hydraulic? If I had the bike in front of me I would find that sound. I am appalled that after $800 spent, pro mechanics can't find it. If it is a brake caliper and you heat it up to the point where it is making noise you have to jump right off and spin stuff to find it. Even a few seconds of delay will allow the part to shrink back to a noiseless state. Finally, is the sound louder in some gear combinations than others? I thought I heard a change in the quality of the sound after a shift. Much longer and better quality videos are needed if any useful help is to be forthcoming. All I have for now.

Maybe use a selfie stick or equivalent to put the microphone nearer or further from various points to help narrow down the source? I was going to guess stoker seat or rails or post, but seems like she would be able to feel something moving for as loud as it is.

Thanks for the feedback so far. It's been really frustrating. To be fair the LBS has been working well with us to resolve, but someone there is going to have to ride it out for 4+ miles to isolate the sound.

We continue testing ourselves too. We've eliminated the PAS system, including switching back to the original front wheel, same results. I stayed off the seat, she stayed off the seat no change. I unclipped and pedaled with her unclipped, no change so it's not the cleats.

We spent time on the climbs where it gets louder. I pedal with her unclipped and it's bad, like a violin made out of barbed wire. I unclipped and she pedaled. Lower sound almost baritone and she is thinking rear hub. Could bearings breaking down fit the pattern of- miles to begin, most pronounced under pressure, no sound unless pedaling?

So it only happens when you are pedaling - correct? Not when coasting?
If so, then that clearly indicates a problem with the drivetrain.
You said you already replaced bottom brackets and chain. So that eliminates a lot of stuff.
All you have left is the rear wheel.
Maybe you can try swapping out the rear cassette or even the rear wheel temporarily to see if that is the problem?

Not necessarily IMO, pedaling introduces forces and torques throughout the bike, so it would indicate that it is related to putting power into the drivetrain. It could be drive train, it could be other.

Recording video with a selfie stick is an excellent suggestion. I once chased an annoying click and tried a usb voice recorder stuck in various places but it was difficult to get a lot of data points and quick feedback. I’ll remember this suggestion for the nest time.

Given the cadence, duration, and frequency of the noise, I am still stuck on the brakes. It sounds to me like a rotor is rubbing. Have you tried lightly squeezing each brake while pedaling during the noise and noticing if the sound changes? Squeeze lightly and slowly alternating front and back. If it’s a brake, you will hear a change.

I believe this is a ebike. Hub or mid drive? Does the sound change based upon the PAS setting? Have you tried riding without power longer than required to hear the noise to appear? Motors generate a lot of heat an have a large thermal mass which takes a while for the temperature to raise. Our front hub motor sounds different as it warms up. I would think that if it was the motor, the sound would be lower in frequency and more muted/muffled. You can try playing with the motor settings to see if changes in the motor characteristics affect the noise.

perhaps a picture or two of the bike would give something to look at and spur some thoughts.

We brought it to the LBS and asked them to pull the rear hub apart and inspect. Great feedback on that possibility. It would make sense that it is loudest when climbing because all of the weight is transferred to the rear of the bike.

On the electric, I tested with and without the front hub on and the same with the PAS magnetic disk.

Drivetrain all parts replaced at this point except the front crank, LBS inspected and found no wear.

Fingers crossed on the rear wheel.

So I completely missed that this is an electric assist bike! I thought PAS was an incorrect naming of IPS. Why wouldn't the electric hub not be a person of interest?! I would LOVE to be wrong, but I doubt very much that the rear hub is the problem. Unless there are ceramic ball bearings in that hub I can't think of any reason a hub would make a sound like that. OTOH I can think of a half dozen reasons easily why an electric hub might make a sound like that. I am (again) assuming that by the bike was tested with the PAS on and off that that did not mean that the hub was removed entirely and a different wheel tested in it's place. My LBS is frustrating in their unwillingness to even sell parts for a recumbent or e-assist or anything not a standard roadbike. But this LBS should have long since recommended the o.p. take the bike to a dealer of e-bikes because I am betting the farm that the problem lies somewhere in the motor. This really isn't fair though, as much as I (we) like a challenge, the people who have SEEN this bike, up close and personal, are in the best position to troubleshoot. All the rest of us can do is speculate wildly.

As the o.p. said previously "We've eliminated the PAS system, including switching back to the original front wheel, same results." So they have already ruled out the electric (front drive) hub.

I played the o.p. video for my wife (blind) to see what she might think. Her ears are amazing and have certainly done their fair share of tracking down weird noises from tandems over more than 12 years. She says drivetrain, maybe brakes. The four mile delay before the sound starts really points to brakes and this could be tested by doing an insane amount of braking in a shorter distance, say 1 mile. The LBS might not have the patience (even at shop rates) for all that lead time so maybe the bike could be brought to them already warmed up, as it were? I don't know, seems to me swapping in a wheel from the shop could have quickly eliminated (or implicated) the rear wheel without the time (and $$) of a hub rebuild. Right at the end of the first video my wife and I both hear a gear shift take place and an immediate diminishment of the sound. Dumb question: what gear combinations are favorites? Are any of them cross chains? Our latest tandem seems to have no tolerance for much more than three rear shifts and there is no trimming possible with the indexed front derailleur. Almost the only thing left is the frame. Are there any plans to test the welds for soundness? I didn't catch the brand of the bicycle on the boom tube but ongoing costs of investigation IMO should be weighed against what a used model of the same type goes for presently on Craigslist. FWIW.

Tandem is a 2006 Cannondale with disc brakes. LBS took the rear hub apart and cleaned it up, lubricated. Mechanic said it was pretty dirty. Rear disc brakes were also readjusted. Mech is working on obtaining bearings for the hub.

Rode it for 26 miles, no sounds or rubbing. Issue is definitely in the rear hub area so thank you for the direction on that, wish I had posted that video a long time ago so I could have saved a lot of money. On the flip side I basically have a brand new bike.

Great! Glad you found it. One thing you can count on with a tandem, when you find and fix a vexing noise, another one will soon appear 🙄