NoWhammies

Looking for some guidance/feedback.

Bike: BH Aerolight 6.5
Issue: Seat post creaking.
Current fix/status: The manual from BH states to put FSA carbon paste on the seatpost and then insert/tighten the seat post to between 5 and 6 Nm. When the seat post has a fresh application of FSA carbon paste, the bike is silent. All good. But come the second ride there is some slight creaking and knocking. Third ride the creaking and knocking is even worse. Come the four or fifth ride the bike is almost un-rideable because of the constant creaking and knocking coming from the seat post. The only way to fix the issue to rinse and repeat the application of carbon paste. And then the process starts over again.

So I am stuck. Anyone have any suggestions on what I can do? The reapplication of carbon paste every five rides is not a sustainable solution.

maddog34

try a layer of wax paper instead... worth a try... and relatively inexpensive too.

mpetry912 

I am not a fan of carbon paste

but I suggest you apply your lube of choice to the seatpost fixing bolt and the saddle clamp bolts

and then see what happens

/markp

HillRider

Any chance the seatpost is slightly undersize?

SoSmellyAir

I had to look up BH Aerolight; it is an exotic: Bike of Carretera AEROLIGHT 6.5 - BH Bikes

It appears to have a fully internal seat post clamp with a hidden bolt? My Cannondale Synapse also has a fully internal seat post clamp, and I find that it is cleaner and more effective to put CF assembly gel on the clamp and on the interior surface of the seat tube opposite to the clamp rather than on the post itself. This is relatively easy to do on my bike as the internal seat post clamp is very close to the top of the seat tube. But in your case the seat tube extends so much further up than the top tube and there is no indication of whether the internal seat post clamp is located. So, good luck.

FBinNY 

+1

Creaking means movement. There won't be movement unless the post is undersized and free to move within the seat tube while clamped at the top.

Take a quick look at the slot in the frame. If clamping closes the top by more than 0.6mm then the post is 0.2mm undersized.

If the top of the slot closes between 0.2mm and 0.6mm the post is the right size, but there's a tolerance issue, ie. frame a bit large, post a bit small.

My favorite fix for undersized posts is to use gummed paper package sealing tape. If you work carefully, only the lack of creak will give it away.

GhostRider62

I looked at your bike's clamping mechanism. I have an aero seatpost on my bike with a somewhat unusual method (tension used rather than compression). Mine gets noisy with carbon paste at a certain place. I use grease instead and it works better (less frequent maintenance). I suspect your creaking comes from the where "wedge" is loaded into the seat tube and would grease there at that point. Any change in your saddle weighting (hit a bump or even slightly position yourself differently) will load that point, Grease will probably extend the wear.

andrewclaus

I have very narrow experience here, but saw this problem on a donated bike once. It only happened with the shorter test riders, with a longer length of post in the seat tube. The post would "pivot" in the clamp and the lower end would wobble, very slightly, inside the tube, with an annoying click. It seemed the ID of the carbon tube was slightly larger at its center. One solution would have been to shorten the post.

Kai Winters

How much seat post is extended? How close is it to the max extension?
Creaking is movement as has been stated and a seat post should not be moving.
Have you thoroughly cleaned all carbon paste from the inside of the seat tube? Also the clamping mechanism? It's possible there is some contaminated material internally. Generally the sound is from an air gap so I suggest removing the clamping mech, if able, and thoroughly degreasing the parts and inside of the seat post clamping area as well as the seat post itself. Inspect all parts for wear or damage, regrease all areas and reinstall, monitoring for the sound.
Good luck...

Robert7659

A bit like hiccups, comes and goes and nobody knows why. Sometimes temperature changes, often playing with the seatpost, loosening, tightening, moving around.

Iride01 

Are you certain it's the seat post and not your shorts rubbing on the saddle and making a squeak? I had that once with a particular brand of saddle. So putting the wax paper from your first reply in this thread between your butt and the saddle might help. Or just put some sort of dressing appropriate for your saddle cover on it. I think I finally resorted to just spraying the nose of the saddle with some silicone spray lubricant.

Kontact

You have to investigate the post in the frame, the clamping mechanism and the seat clamp mechanism. Any of them can make noise.

Posts that go too far down in the frame will also make noise. On many bikes with aero posts you are expected to cut them.

zandoval 

Hey... Thanks... There is another Tid-Bit for my U.S.F. file...

drlogik 

+1 Any chance the seatpost is slightly undersize?

I thought the same thing. If the OP applies carbon paste and tightens to spec and it's ok for the first ride and the creaking gets progressively worse, yes, that would tell me that there's movement.

Maybe clean all of the carbon paste off, all of it and wipe down with alcohol, let dry and re-assemble, tighten to spec and see if you can get the seat post to move up or down or laterally with your hands. If there's any movement at all the carbon paste won't help for long.

I'm also thinking that if you been doing this a few times then the carbon paste may actually be sanding both surfaces and making the seat tube minusculely larger and the seat post smaller...which would make the situation worse over time.

Mtracer

My bike did that about a year ago and it has started up again recently. It is more a popping than creaking in my case. First time, removing cleaning and then carbon paste. It is a carbon frame and carbon post. Solved the issue. In my case I believe it is a bit of grit that gets in there.

So maybe be sure to clean the post and inside the seat tube, then apply paste or grease.

As for movement and noises, a seat post is going to move unless the post and seat tube are truly rigid. They are only clamped at one location. There is some flex so there will be a tendency for some movement, especially further from the clamp, even if there was a perfect fit. It wouldn’t take much movement and some binding to cause it to pop. Could very well be that grease alone would be better than paste. Though, I don’t think the grit in carbon paste causes issues like grit from dirt. But I have no idea what the gritty stuff in carbon paste is.

NoWhammies

Wow. Just wow. Thank you all for your comments. So many good and helpful tips.

The seat post is the OEM post that came with the bike. If the seat post is too small, that will be a real pain in the butt to fix/figure out. The comment about finding a wedge though might help if I can figure something out. drlogik suggested that the carbon paste between the seat post and the bike frame might have acted like sandpaper and worn a small gap between the two now has me concerned. You might have something there though as I started out with less torque on the seat post so maybe the micro-movements has sanded away some of the frame.

Kai Winters the suggestion to thoroughly take everything apart and degrease is a good one. I have taken the seat post apart and cleaned it off, but not thoroughly with alcohol, degreaser, etc. Perhaps the simple wipe down as not enough to thoroughly clean the seat post. Getting down into the frame to clean off any carbon past though might be an issue. I will have to think up something creative to make sure that whatever I do use to clean the interior of the bike does not get dropped down there and stay forever trapped in the frame.

GhostRider62 when you say to use grease, would that not cause more problems for me? My understanding is that grease is put in place to help things move. To make sure they slide. Would not putting grease on my seat post just cause the post to slide more?

SoSmellyAir I have put the CF paste on the clamp/wedge AND the seatpost in my attempt to stop the creaking. But from what you are suggesting, I am better off putting the CF on the edge only and on the seat tube opposite the clamp. That could be a challenge as I cannot get my hand down into the seat tube to apply the CF paste. Also, there is a gap oppose the seat tube to allow for the tightening of the internal bolt/post.

mpetry912 I did apply some grease to the seatpost fixing bolt but not the saddle clamp bolts. Perhaps I will give that a shot. Your recommendation was to apply lube though. Any issues with applying grease? My grease of choice is park tool grease.

Lastly, maybe this is a silly question, but would the type of CF paste make any difference? BH recommended using FSA paste, which is why I went with that. Although my LBS is out of CF paste and it telling me to go with muc-off CF paste now.

Iride01 Yes I am certain it is the post. I have tried different saddles and the creaking is still the same. Always there.

Thanks again everyone for your help. I really appreciate it. I went for a ride tonight and the bike was creaking and groaning like crazy.

Kontact

Carbon paste does not have sand in it and does not cause wear.

You need to look at all the spots I mentioned.

maddog34

seriously.. try the wax paper... all the fancy pastes and greases didn't help. TRY IT. it worked on my CF bike's post.... low tech and cheap.If it doesn't work, use it to wrap lunch for your kids, or baking or something. Or go "high tech" and wrap it with plastic wrap.. it doesn't hold up as well, but it looks nice and shiny! I know someone that tried all weather caulking.. it worked too. Gasket goop for automotive work would be a good try too... (the gasket and caulking thing may create a PERMANENT bond if you fail to coat the post with something really slick first... )

Be bold, EXPERIMENT... or enjoy the creaking sound as it serenades your ride... think of it as a VERY Expensive and fast Cricket.

FBinNY 

I did a search and see the frame, and cannot offer a simple solution.

Unfortunately, this is a poor design which allows excessive flex in the unsupported seat tube above the top tube and, depending on seat height, between the bracing members.

The first step is gauging how sloppy the seat post fit is. If it slides easily, it's too loose, so you need to consider building it up to get a tighter fit. Being oval makes it more complex, but it is doable if you're willing to do the work.

A key element is that the post is clamped only at bottom, allowing its entirety to move within the frame.

Solving mechanical issues is like this is like treating fever. You can take aspirin to lower it, or address the virus or whatever else is causing it. So, if you're serious about solving the problem, focus on the underlying cause ----- sloppy fit, flex and/or relative movement ----- rather than the squeak itself.

SoSmellyAir

Yes, what I am suggesting is that you need a little bit of carbon fiber assembly paste on all surfaces that are clamping on the seat post, e.g., clamp, wedge, interior of the seat tube / seat mast, etc. If you cannot reach with your fingers to apply the paste, consider using a small paint brush. The CF assembly paste does not have to be a perfect layer; a few blobs in the right spot and the clamping forces should distribute it well enough.

NoWhammies

Thank you everyone. I will put some time in with the bike this weekend and see what I can come up with. I took the bike for a ride last night and the creaking is definitely getting worse. Really detracts from the ride and I am worried I am doing some slight? damage to the frame. Maybe I am just too paranoid...Anyway.

Kontact I will go back and have a better read of your posts. Thank you.

maddog34 Pardon my ignorance. Just so I am clear. The plan is to wrap the wax paper around the seat post and wedge. Kinda like a taco, leaving the back end of the seatpost exposed so I can tighten the bolt. Then slide the seatpost into the frame and tighten. Correct?

maddog34

that's a good first try... mine is an old school round post.... i just began reviving a cannondale lefty today... CF parts all over it...it has a single layer of electricat tape on the carbon fiber post, not sure if it's a full wrap job... i'll know soon enough... And the bike appears to have many hard miles on it....any bets on if it creaked before the tape went on..? good luck exorcizing your crickets.... i still fight an FSA crankset on my Diamondback rail trail speedster... every five rides or so, apart it comes, fresh grease and fresh torque on the screws... at least the CF seatpost is doing well... hmmm... i wonder if Teflon Tape on the Crank screws might work... hmmmmm.. next time... or maybe i'll finally slap a hollowtech II in... i have one on the shelves, and a fresh BB...

Kai Winters

Inspect the seat post carefully for cracks, etc.
Just had a Venge come in with a complaint of a creaking sound.
We inspected all the usual suspects but nothing...we removed the seatpost to clean/degrease/grease with carbon paste and voila found the problem...a cracked seatpost...cracked from over tightening.
Hope this is not your problem...luckily for him we are still able to get a Venge seat post from Spesh...whew

BikeLite

Tony Marchand on youtube just did a video about this issue.

NoWhammies

Thanks everyone. I am takin the Aerolight in for a bike fit next week and have decided to leave the post as-is until the fit. With my luck I would solve the creaking issue only to have the issue re-emerge after the bike fit.

I will definitely have a look at Tony's video. Thanks.