Tandem Cycling - Cannondale tandem: that shush shush pause noise

Got a new Cannondale Mountain Tandem 2006 in April 2006.
Over the past 16 months or more have been annoyed by this phantom shush shush pause shush shush noise (pardon the audio attempt) that only comes up after at least half an hour of fairly hard riding and only when pedalling, the more power applied the louder it gets. Embarrassing. Clearly audible to passing or passed cyclists. Appears to be coming from around the back bottom bracket or futher back, perhaps the rear hub. It is not the disc brakes
We have checked pedals, and changed bottom brackets, cleaned the cassette and oiled the rear hub and greased the eccentric, tightened the cranks. At times it appears to be in sinc with the right leg down thrust. It is driving us nuts.
The bike shop has also not been able to isolate it yet.
The rear hub is the only component that has not been fully checked yet.

Any body come across this?? Many thanks

Check the quick release skewers. Noises sometimes travel. A little grease on each skewer will fix it.
Usaully its more of click, but it's one of the things that you didn't list as checking.

You don't say whether or not you have a stoker's suspension seatpost. We had a creak that appeared to originate from the captain's crank area only when applying power on the right side and that only happened about 1/2 hour into a ride. It turned out that the stoker's Tamer seatpost needed lubrication.

We had a squeak that drove us nuts. I adjusted and lubricated everything I could find on the bike that might require adjustment and lubrication. Still squeaky. Then I put a spot of chain lube on two pivot points on the Brooks B67. Problem solved.

Random bike noises really bother me.

Cheers!

We have the same bike. The description you give of the noise makes me think of the tires. Do you still use the original Kenda K-Rad tires (26x2.3)? Ours tend to be very noisy and the sounds oscillates along with our pedaling (even though we spin pretty nice&round). The fact it only starts 1/2 hr into your ride might be explained if you first warm up for 1/2 hr. The sound indeed increases substantially as the speed goes up.

On another level. Do you oil the hub? Do you mean the DT Swiss freehub? If that works, then good for you. But plse note that DT Swiss requires that their special (expensive) grease is used. This grease is based on Molykote TP42 (made by Dow Corning) which is a paste. I got myself a tube of it and mixed it with some teflon grease and oil. It works great, no hick ups and very smoot freewheeling. As we live in Geneva, Switzerland we freewheel a lot on the long downhills and I don't like to have a machine gun in the back. For more info have a look on the DT Swiss website http://www.dtswiss.com/getdoc/4e78add1-601b-4af0-b7c7-07f7e2e2a8df/Datasheet.aspx
This is for the newer 540 tandem hubs, but from a maintenance perspective nothing has changed compared to the Hugi DT Swiss TD hubs that were stock on the 2006 Cannondale. I know of people who use any type of decent grease on the freehub, but oil should not stick enough in place to guarantee long enough lubrification. Just want to help you make the most of what I think is a fantastic tandem.

Would agree that perhaps it's those knobby tires and the noise only happens after warm-up and with both riders pushing hard on pedals.
If you have some non-knobbies sittin' around, give them a try.
The suggestion of clamping down a bit on rear QR is another one.
Also, set up pedals 90-degrees OOP (out of phase) and see it that cures it (that would eliminate the surge effect).
Then again, it could be something completely different.
Yup, them noises can be most annoying!

Great to have your responses, certainly making us think outside the square. I'll try the lot. Thanks to all.

Merlinextraligh - I did grease the rear skewer when I had the back wheel off to oil the hub (although seems the latter has limited benefit).
SWC7916 - the seat post is the original that came with the tandem. Will try a lube but I feel the noise is lower down. We made a video/sound recording with our Sony Cybershot held by the stoker as low as she could go. The noise becomes almost grating esppecially when we put on full power on a hill.
Brewer 45 - I think we have virtually done the lube all round and no Brooks just Terry's. No I think it is low down. thanks anyway.
Carrefour - We have Schwalbe Big Apples (slicks) front and back. Not a single pucture since we have had the bike. Not coming from the tyres. They have their own hum which is music to our ears when we are going quickly down hill such as from Splugen down to Chiavenna, Albula down to Thusis and Ecole dela Schulgt. The disc brakes were great. No noise there except when braking. Major disappointment was the rear bottom bracket failing fortunately at the end of our 6500km European tour in 2006. Thanks for the hub lube tip. will follow up.
Zonatandem - I'll try the OOP. Probably do all the above including changing the rear bottom bracket again this weekend. So I will be able to report back pretty soon.

"Major disappointment was the rear bottom bracket failing fortunately at the end of our 6500km European tour in 2006."
I was told by other tandem owner that BB is sensitive part indeed (any model on any tandem). How did you notice that BB was failing? Not running smooth, noise? Or was it more dramatic? I was told that in worst case BB can brake open in which case even the frame would be at risk. Did you replace with same BB as original or did you change to other brand?

Avid disc brakes are great indeed even though I changed to Koolstop brakepads as soon as original ones are worn. Koolstops are smoother and make less noise.

Have had a Phil Wood bottom bracket last 64,000 miles on front of our Assenmacher tandem and the stoker's BB lasted 30,000-some miles. Sent stoker's BB back to Phil with a note giving it's mileage; he sent us a brand new BB with a note saying 'after all those miles, you deserve a new one . . . no charge!'
On our Colin Laing tandem had the Phil BBs last 56,000 miles.
On our Co-Motion tandem had our Syncross BBs last 57,000 miles. All without any issues except for the aforementioned Phil. All those tandems were sold after the stated mileage and the BBs probably are still functioning.
Quality lasts . . .

Carrefour
Heard an intermittent crack like a rifle shot - thought some kid had hit the frame with a catapult - on full power near top of hills. Obviously (with hind sight that is) one of the bearings got trapped. Started making a mild grating noise at times. Could not trace it. Thought is was the pedals. At about the 5000 km mark took bike to a shop in Tubingen in Germany - could not trace it. In another 1200 km my wife/stoker said she thought the pedal was getting loose. Was the whole crank shaft. So then we knew at last what it was. She could not pedal at all in the last 80 km into Amsterdam. BB totally collapsed. Replaced it with a new Truvativ bb ie same type. No housing damage - just lucky - or a new frame. The new bb has not collapsed. But now we have the shush shush noise (no cracking). Could not trace this noise which I suspect was there along with the bb noise so we could eventually not hear it. Thought it might now be the front bb. Replaced that - still there. Thought the new back bb may have been defective - put the original front bb on the back. Still there. So now I have just put in new bb on the back. We will test ride tomorrow. (the new Truvativ bb left cup had a defective thread so had to use the old front bb's). I suspect it is the rear hub - when heated expands and touches somewhere - it has a buckled wheel rhythm. Heard from the local bike shop manager that the Truvativ bottom bracket on his single mountain bike (which gets a hammering) does not last long he has been through three in a relatively short distance. So it seems the Truvativ bottom bracket is the Cannondale tandem's Achilles heel. Thanks for the Koolstop tip.

Zonatandem/Carrefour

You are obviously right on quality re the bb issue. It seems my option is to go to Shimano or Durace both of which will require changing all the running gear - I'm told - and a pile of dollar bills. Or to another tandem.

Pel and Zonatandem,
Thanks for sharing your valuable experiences. Very useful.
Agreed that quality has its cost, but sadly enough the opposite is not always true. Not all expensive BBs are quality. I'm sure PW are top, but just as for changing to Shimano parts, this would require full new set of tandem cranks as they only do squares. Plus personally I'm absolutely pleased with the Truvativ cranks, though ready to see the rear BB fail. And as we have a trip over the Route des Grandes Alpes (Geneva, Switzerland to Menton, France across the alps) and back planned end of June/start of July I want to avoid as much as possible any major technical problems.
I have been looking at ISIS BBs from CrankBrothers, SKF and Raceface in the hope that these may be better. Truvativs are indeed known for failing pretty frequently. http://bike-components.de/catalog/Cranks+%26+Bottom+Brackets/Bottom+Bracket+MTB/Cobalt+CrMo+ISIS+Innenlager http://bike-components.de/catalog/Cranks+%26+Bottom+Brackets/Bottom+Bracket+MTB/BXC-300+ISIS+Innenlager
http://bike-components.de/catalog/Cranks+%26+Bottom+Brackets/Bottom+Bracket+MTB/Evolve+XC+ISIS+Innenlager
Feel free to comment if anyone has any ideas/experience with these.

Pel, I'm sure not ready to change tandem. We got ours only in May 2007 in the X/M size once I saw how much the 2007 Streettandem had been downgraded. Plus my wife loves the yellow/orange. As she is from Boston we had our "local" bike shop do a search where in the US there would still be a 2006 model available in that color and size. They found one in Arizona. I went to pick it up personally in Boston and managed to fly it to Europe for free. The US model also has the mechanical brakes which I prefer over the hydros on the euro models and they are so much cheaper back in the USA. So thank you America.

Pel,
Have further been thinking about your shush shush pause noise. How does the sound compare with the humming from the tires that you mention. Is it louder, more grinding,...? This may help me imagining the noise as I know exactly what you mean with humming tires.

If it only happens when pedaling it almost cannot come from the freewheel. And even the hub seems excluded to me as the bearings there are supposed to last way longer than the BB ones. Plus hub bearrings feel more any team's weight (light or not) than the pedaling force (I guess). What size are your Big Apples? Do you have the 2.00 or the 2.35? If the latter, then is there any possibility that they rub the frame under heavy pedaling? I know the stock tires are that size and don't rub, but tyres of same size may be shaped differently. Just an idea. Hope you quickly get rid of this.

The only sound I can think of that would have been affected by the BB failure and then replacement would be front deraileur rub. Does the noise happen no matter which gear you are in?

The description of the sound however makes me think the tire rubbing the frame is the most likely cause. You might want to check the tension on your wheels, not just for trueness, but make sure the spokes have not loosened up enough that a wheel can flex enough to rub during climbing.

When diagnosing these sort of problems you need to pay attention to all the clues. You've caught a few of them, like only during pedaling, and worse under greater loads. Here's some other things to consider:

A problem with your cogs will produce rapid clicking noises at even intervals that don't match a particular position on the crank. A problem with the crank or pedals will produce a clicking noise that usually lines up with a particular location on the crank. Chain problems, if they only affect a few links will have a less frequent noise pattern and will have pauses in between the noise as the "bad" chain travels over sections where it is not in contact with another surface or usually traveling through the rear deraileur, where it is pivoting the most.

Because of the pause in your noise, I'd consider the chains as a possible cause.

I don't think that listening for the noise while pedaling in a work stand is likely to work because the noise seems to be related to how much force is on the the drive train, however you might be able to get the noise to occur at much slower speeds by applying a brake. You could then have someone else listen for the noise.

Hi again Carrefour - glad to be able to share info.
On the BB do not worry about it overly. Simple take a spare BB. You will have plenty of warning before it is unrideable. our lasted 6,500km as mentioned. The noise is definately not the tires - else it would be there all the time. I have checked the clearances - no problem even when under power. And why the half hour warm up first? It does become a grating noise eventually. We have 2.00 tyres on front and 2.35 on the back. The latter by mistake but turned out to be good for the stoker - more comfortable and incremental rolling resistance almost nil. Yes - mechanical as opposed to hydraulic disc brakes - easier to fix and more reliable. No concerns reboiling on 30 km fast descents. Have a great trip. We picked ours up in LA on the way to Europe. Sad to see the down grading of the street tandem in relation to the Mountain Tandem.

Pel,
Thanks for info. I'm running out of ideas in re. to your noise for the moment. Would be helpful to see live, but a bit too far ;-) Plse do post your findings. I hope you get this fixed soon, because I know I good it feels to have a smooth running tandem. And keep up the fun rolling along.

Thanks Possum Road Kill
I know the front derailleur noise - no not that. The half hour warm up also does not fit.
Will check spokes again but was interested to note how tight they were some time ago. It is definately not the rear tire as it would have worn through abnormally by now 18 months. More of a grinding noise. Chains maybe but no bad links? will check. Putting brakes on and pedalling against them does help to aggravate the noise. Was thinking of putting bke on a wind trainer but tricky for a tandem at full power and could not find one to fit.

Just got to crack this one.

Just a quick update. Put in the new Truvativ bottom bracket on the rear (front is new too) a few days back. Took it for a 30 mile ride today 28 May. No sound for first half hour then started up again quietly initially ie the shush shush noise then increased and by 20 miles going on a long slight uphill with near to full power for five minutes a clear, loud grating noise coming from the back at every down/power stroke. Cannondale dealer was riding next to us and heard it clearly. Thinks it is the rear hub. will be talking to Cannondale to day.

Thanks for update. I'm absolutely interested in hearing the final outcome, so plse keep us up to date.

Just a quick update....by 20 miles going on a long slight uphill with near to full power for five minutes a clear, loud grating noise coming from the back at every down/power stroke...

I am very curious too. I know that you said earlier that it was definitely not the disc brake rotor rubbing and that you thought the spokes were tight but I still wonder about them and I have experienced what may be a similar issue. We currently have a 40 spoke wheel on the rear after having rim cracks on the original Sweet 16 and the second Sweet 16 replacement. Anyway, we had the 40 spoke wheel made by another person and when it was delivered, it was clear both by audible pitch of plucking the spokes and on a Park tensiometer that the spoke tensions were not even.

I evened them up and we've ridden them over 2000 miles including our recent winter and early spring season that frequently meant riding on roads damp with the salt and sand mixture the highway spreads. Because of the salt, I am frequently cleaning and lubing. I even dripped a drop of triflow into the spoke nipples occasionally because I didn't want them corroding and getting stuck.

During this past month, we started getting an occasional noise like the swish swish pause you originally described. My wife / stoker heard it before I did. I suspected the rotor rubbing but when I would get off, spin the wheel, and look and listen, there was no rubbing what so ever. It was not timed with each power stroke but it was rythmic in regards to where I would be in my pedal stroke and it was when I was applying power but not every stroke. When we were on some hills that took us to one of our lower gears that was nearly one-to-one with pedal stroke and wheel rotation, then it was on every power stroke. I hypothesized that some but not all spokes were loose enough that when we were on a power stroke with the wheel and looser spokes in just the right position that the rotor would get pulled just enough to rub against the pad. Depending on the gear we were in, it might take several rotations for the power stroke to be applied at the moment when the looser spokes were in the position to be subject to the power stroke pulling.

So...I checked the spoke tension on the wheel. They weren't as even as I had left them months before. The reading on the Park varied from 18 to 23 with the tire off. I trued and retensioned the spokes all to basically 23 and the noise went away. We were very pleased.

If the tension is not high enough on the spokes, the tension gets too low when the spoke is at the bottom as the wheel rolls (when the spoke is compressed as it bears the weight / force). and they can loosen. Some wheel builders will use a compound that sets up after the wheel is built to resist this. Some wheel builders such as Jobst Brandt (author of the The Wheel Book) thinks that is unnecessary if the tension is correct. At any rate, I think that my lubrication of the spoke nipples contributed to the spokes loosening.

Your problem may be completely different and may be the hub but I thought I should relay my experience just in case.

Bloomington, IN

If the tension is not high enough on the spokes, the tension gets too low when the spoke is at the bottom as the wheel rolls (when the spoke is compressed as it bears the weight / force). and they can loosen.

If you omit the comments in parenthesis, you've got it right.

Although technically a bicycle's spoke network holds a wheel in suspension, it would be more accurate to describe a wheel as a structure that hangs from the spokes instead of standing on them. As you note, as a wheel rolls the spokes achieve their lowest tension as they move through the 6 o'clock position and distribute the loads around the rest of the network. Having a wheel with low tension in one or all spokes will create all kinds of problems, including noise and truncated spoke life.

If you omit the comments in parenthesis, you've got it right...it would be more accurate to describe a wheel as a structure that hangs from the spokes instead of standing on them...

You probably know those are fighting words with engineer Jobst Brandt, author of The Bicycle Wheel Book, over on rec.bicycles.tech. There are multiple threads with arguments over that statement. I think it is one of the instances where the words fail to capture what is happening and one really needs to look at the tensions in the spokes. Brandt claims that it is correct to say that a spoked wheel stands on its spokes. I believe he would say that when you do a finite element analysis or measure spoke tensions in reality, the only change that is measured is in the spokes at the bottom of the wheel and thus it is correct to say that a wheel stands on its spokes instead of hanging from the others.

Whatever the case, I hope the OP figures out what is making his noise:)

Bloomington, IN

You probably know those are fighting words with engineer Jobst Brandt, author of The Bicycle Wheel Book, over on rec.bicycles.tech.

:thumb:

Yeah, I know... :trainwreck:

I figure with all of the hair splitting going on as of late I'd stir the pot...

Quite an education for me on wheels/spokes. Have not adjusted in two years but will now get the tension meter and check it out. Thanks for all the info.

incidentally Zonatandem I set the cranks out of phase ( oop) as you suggested. The noise still came up. But I changed back to into phase ie parallel on both sides because oop was a disaster for us. Threw our balance out and was very jerky. The latter possibly because of the power difference between me and my stoker/wife.

Second incidentally. The Cannondale dealer riding with us mentioned the not long back they had a similar problem with a Cannondale Road tandem. Struggled for six months trying to solve it. Ironically started out by changing the rear hub. Still there. Then changed every thing else in stages including the frame. Still there - quite clearly audible. So they changed the rear hub again. Gone!

What are the chances of have to dud rear hubs in a row? Hope this does not happen to us.

Hi, I had a very similar problem with our Rolf rear wheel. Developed sort of a scraping noise when at low speed, high torque riding situations. After persuing the brake theory with no luck, I took the free hub body off and noticed the pawls looked like they were rubbing against the hub body. Lacking the proper lube, I applied a little chain oil. That seemed to do the trick. No more noise. Good luck.

Hi, I had a very similar problem with our Rolf rear wheel. Developed sort of a scraping noise when at low speed, high torque riding situations. After persuing the brake theory with no luck, I took the free hub body off and noticed the pawls looked like they were rubbing against the hub body. Lacking the proper lube, I applied a little chain oil. That seemed to do the trick. No more noise. Good luck.

Will try that, thanks Mikebikey. I did try to oil the hub with the wheel off and lying flat (both sides) for max penetration but have not yet dismantled the hub.

Pel, careful. The bearings don't like oil. If oil gets into them, it will eventually mix with/wash the original grease away. If you want to take the freehub off, pulling hard on the cassette will do it. Make sure you remember the order of the components.
Good luck.

spoke to the Cannondale dealer (boffin) on Friday 30 May who heard the noise and is helping us with the issue. Apparently Cannondale Australia are talking of replacing the existing Hughi DT Swiss rear hub but with another basically one-up in the hierarchy of hubs. Details forthcoming. Not sure whether Cannondale USA is involved.

Useful thread, thanks. I will be regreasing my freewheel too as a phantom noise started recently. It's probably related to a 2 hour drive in the rain at high velocity with the tandem on the top of the car.

Just for interest, I've had a couple of strange noise sources: Sweat corroded aheadset spacers creaking when climbing out of the saddle, the manufacturing bobbles on the tyres making a swooshing noise only noticeable on the workstand, loose chainring bolts causing creaking when pedalling hard.

OK - no more oil Carrefour. Thanks. Only had one application before this useful thread. But it is beginning to look like the Hughi hub has a design defect not related to oiling. Pretty sure of this because the noise was there in varying degrees almost from puirchase - although at that early stage we had no idea where it was coming from.

Mrfish: did tighten the chain rings. It is not a creaking noise. Clearly grating once it gets going. Thanks

Another update at 22 June - apologies for the drawn out process but out of my control.

As mentioned bike shop agreed it is the rear hub which has a double as opposed to a single housing - the former apparently causing the problem/noise. Bike shop prooved that we had tried, without success, to identify the noise well within the one year warranty period but Cannondale not willing to cover under warranty even though the hub clearly has a design defect as indicated by two other hubs we know of.

So now I have to argue the warranty issue with Cannodale direct.

In the meantime we have ordered a new hub (at a slightly reduced price) but not of the same DT type - apparently one up in design - having a single shell housing.

Will let you know, when we have the new hub on, whether it solves the problem.

Unimpressed with Cannondale response on this and would not recommend the Cannondale tandem based on our experience with the hub - but brakes and frame are first class.

Just for interest, I've had a couple of strange noise sources: Sweat corroded aheadset spacers creaking when climbing out of the saddle, the manufacturing bobbles on the tyres making a swooshing noise only noticeable on the workstand, loose chainring bolts causing creaking when pedalling hard.

Last two weekend rides started getting a swooshing noise as well and thought of this thread. In my case, it was the loose chainring bolts causing the problem. I've been checking all over the bike though as I think 20 miles of expansion cracks on the Eastern Sierra ride have shaken some parts loose.

Hi Pel, I hope you got your issues sorted out. Just to let you know that we just came back with our Cannondale mountain tandem 2006 from our 1278km over 15 cycling days & 2 resting days from Geneva to Menton and back across all mayor french alps cols without any technical issues. No flats, ISIS axles and brake pads survived whole trip. Stoker will complete website asap and we'll post link on forum to share our experiences with you all.

Hello again
Noticed this issue was first posted in May 2008.

To cut a long story short the shush shush noise that started after about half an hour of moderate cycling and then developed into a full on grate grate on each power stroke has been sorted - without doubt it was the original (2006 Mountain Tandem) DT Swiss Hugi TD rear hub that was defective.

After a seven month saga Cannondale came to the part and replaced the rear hub (at no charge for the hub) with a DT Swiss 540 145mm six bolt solid shell hub. Result after some forty kms - not a peep.

Thanks for all the interest and responses to-date.:thumb:

Not sure what happened to my previous attempt today to provide an update on this issue.

However, I noticed the post was first made in May 2008.

To cut a long story short the problem is solved.
Cannondale came to the party and replaced the original DT Swiss Hugi DT rear hub with a DT Swiss 540 (145mm) six bolt, solid shell rear hub ( at no cost for the hub). Not a peep out of it after 40kms.

The orginal hub started complaining with a shush shush noise after about half an hour of cycling and then developed into a full on grate grate on each power stroke.

thanks for the interest and responses todate.:thumb:

Hadn't read this thread before. I was going to post about the hub being the culprit when I noticed there was another page of answers *and* the solution. FWIW: the so called "Zahnscheibe" (what would you call that in English: tooth ratchet?) that transfers the power from the sprockets into the hub is the culprit. Our 2005 C'dale Road Tandem produces the exact same noises under the exact same conditions. From people who deal a lot with DT hubs I've learned that replacing the "Zahnscheibe" with a more recent example normally fixes the problem. DT have had a fairly large batch of these things that made noise first and then died.

As to the BBs: Carrefour wrote on 16-05-05 that Shimano only do squares on tandem cranksets. As road cranksets go, the opposite is true: these are no longer available in square-taper. Not quite sure about the mountain variety but I bet these are only available in Octalink or what have you nowadays at Shimano. The first rear Truvativ (CR)ISIS BB on our road tandem died at 2,500 kms and the next one at 3,500 kms. Being totally fed up with these things I purchased a square-taper Shimano tandem crankset. Installed a set of Sinz Racing BBs (three bearings) and we're totally happy now. Yes, "they say" that SKF ISIS BBs are better but it's a flawed design in the first place. And: what was actually *wrong* with square taper?

Hi dubbelop,

I fully agree with you. When I wrote "I'm sure PW are top, but just as for changing to Shimano parts, this would require full new set of tandem cranks as they only do squares" I meant to say that PW are the ones that only do squares. The "THEY only do squares" referred to PW, not to Shimano. Sorry I phrased this in a pretty confusing way, but English is not my mother tongue.

Happy 2009 to all tandem teams out there:thumb:

just as well to check for loose chain ring bolts, mine were a bit soft - but that was not my main problem as we now see

Hi dubbelop,
I fully agree with you. When I wrote "I'm sure PW are top, but just as for changing to Shimano parts, this would require full new set of tandem cranks as they only do squares" I meant to say that PW are the ones that only do squares. The "THEY only do squares" referred to PW, not to Shimano. Sorry I phrased this in a pretty confusing way, but English is not my mother tongue.
Neither is it mine ...... Only now I realize you talke about square bottom brackets, where I thought you referred to cranksets. Of which PW makes exactly none. Maybe they should, by the way.


Happy 2009 to all tandem teams out there:thumb:
Second that :thumb:

Hi again dubbelop,

Now I see, you are Dutch.:) As I'm Flemish we could technically stick to our common mother tongue. However, I think we would not get much feedback on BF then. OK, I should stop abusing Pel's topic and stick to the subject.

Groeten,
Eric

I have a 2007 Cannondale road tandem with the same problem you describe. We typically ride it once a week, 44 miles. The problem started around the 2000 mile point and it ALWAYS takes 35 minutes for the growling noise to start with a pattern very much related to the down stroke. It was obvious BB noise, but I did everything to remove other things from the equation first. While the noise does emit a similar frequency to say a chain grazing the front derailleur, it is NOT the front derailleur and fails in all 3 chain ring positions. The problem stopps as soon as the pedaling stops, but of course everyone on the road wants me to fix my brakes. Right! I have disk brakes, so just incase they are flexing and touching the pads, I adjusted the pads out so far the brakes would barely work, still failed. I had no doubts about this as the disk touching, say during a turn, is a mush higher freq ring sound. FYI... The BB noise also fails on any gear in the cassette. I have the TruVative Giga X BB, bearing cups are outside the shell. Replaced both and with great disappointment, 35 minutes into the next ride the growling shh shh noise was back, only with a slightly different pattern and growl than before. Again, like your description, this is not a seat post creak or a pedal issue. I've had my wife un-clip so only I'm peddaling, sound lightens, but it's still there and when we reverse the scenario with only her on the pedals, same problem. So the next step was to remove the timing chain (since it allows me to put a load into both cranks) and just have her pedal. Yup, the BB growl is still there. Knowing new parts can be defective, even whole batches of a manufacturing run, I replace only the rear BB based on the last isolation step. Also, I haven't mentioned, but I removed, clean and re-lubed both chains every time another part was changed just to keep everything super quiet. 2nd new BB failed also, growl starts mildly 35 minutes into ride and grows to a very annoying gravel on metal sound by 50 minutes. New pattern, same noise. SRAM/TruVativ admits they have some issues to the dealer and sends us a new complete crankset, front & rear, with bearings and rings, the whole deal. I replace the chains with new during the process. First 2 hour ride was sweet, no noise. 2nd ride (38 minutes) the growl started again and has been that way ever since. If I drop my head down toward the cranks when it's really growling, I can hear the noise being amplified through those big aluminum tubes as if it were a sounding board.
So... did you ever resolve your issue? I'm at the point of going full Shimano for $600!
Dan

My wife's bike had a noise that took weeks for me to figure out, it was similar, it made a noise only when pedaling, and only when moving (not on a stand). It turns out that the rear wheel had one of theose plastic spoke gaurd things that had broken around the hub and would make noise only when the wheel was loaded, and torqued by pedaling.