Another 'noise' thread, need help

[Jaymadd]

I have a knocking noise that has developed recently while pedaling seated. It does not happen when I'm out of the saddle. I've narrowed it down to a saddle/seatpost noise but have been unable to eliminate the knock. I removed the saddle and lubricated the bolts and rails to no avail. My bike is carbon and the post is aluminum. I put my old carbon post back on and noticed that the noise was reduced dramatically however would still occur from time to time (not with every pedal stroke like with the aluminum post). Does anyone have any suggestions? I'm thinking that the fit is not as tight with the alloy post which may be causing the knocking noise.

[dalava]

Did you tighten the bolts to the specified torque?

[Jaymadd]

Did you tighten the bolts to the specified torque?

I have a Richey torque key for the seatpost collar. The bolt that holds the saddle is 3mm and I dont have a torque bit to fit that. The manual states 3.5nm which isnt a lot. I just went out for another test ride with my previous post and the noise was absent. My new post is the infamous USE Alien cyclops which may be the cause of my problem.

[dalava]

3.5nm is really not a lot, especially for one bolt. For example, using 3T Dorico with Specialized Toupe/Romin saddle with ti rails, I have to tighten both bolts to at least 5-8nm, if not more, for it not creak.

I think the relative merits, or the lack thereof, of the USE Alien post has been discussed here, ad nauseum.

[Jaymadd]

Can I use anything on the post like carbon paste or grease?

[dalava]

Carbon paste is for interfaces between carbon parts. If your frame is carbon, i would use it on the seatpost. I think the seatpost head is not carbon, so I wouldn't think you would achieve anything by using carbon paste. I would use a bit of grease if both are metal.

[cinemattic]

Can I use anything on the post like carbon paste or grease?

i think you should have done this when it was installed, no? i have the inverse of you (steel frame and carbon seatpost). had the bike shop throw a dallop of carbon paste inside the seat tube, installed it, and i have not had a problem with it for just about a year now.

if there's nothing in there at all, i would def throw some kind of lubricant in there. i bet it's just the excess tweaking around inside the tube

[Jaymadd]

i think you should have done this when it was installed, no? i have the inverse of you (steel frame and carbon seatpost). had the bike shop throw a dallop of carbon paste inside the seat tube, installed it, and i have not had a problem with it for just about a year now.

if there's nothing in there at all, i would def throw some kind of lubricant in there. i bet it's just the excess tweaking around inside the tube

Yeah, it is aluminum post and carbon frame. You may be right that it is the excess tweaking due to lack of lube. The only thing left in there is a slight residue of carbon paste from the previous post install but that was wiped clean when I put the new one on. I want to make sure that I dont use the wrong lube though.

[Chickenstrip]

I had a similar noise on my SuperSix that I thought was a seat post or possibly bottom bracket. It ended up being a loose headset. Carbon carries sound differently than aluminum and it can fool you! My noise happened when the left pedal was at about 3:00 and the right at about 9:00, but I couldn't duplicate it on a trainer. My headset had no decernable play in it so I never checked it. The wrench at my LBS took a ride with me carrying a bunch of tools and after 20 or so miles and numerous adjustments she found it!

Yeah, I gave her a big tip, and she'll definitely be getting a Christmas card this year!

[Jaymadd]

I'm going to try some carbon assembly compound. Reading the Park Tool description it mentions that it is for carbon, aluminum and steel. Will give it a shot. http://www.parktool.com/product/supe...compound-sac-2

[Jaymadd]

After much despair and anguish I believe that I may have discovered and fixed the source of my 'knocking' noise and wanted to share. I have an Airone saddle and noticed after my ride today that I could move it side to side very easily by hand. I then went to google to see if this may be causing the annoying sound as I pedal seated. Found a suggestion to use epoxy in the hole where the rails attach to the saddle and thats what I did. Just took the bike out for a test spin around my block and NO NOISE!! Still need to do a big ride in order to be sure but all signs point to success!