Cannondale Synapse Creaking Seatpost

MCoolta · July 2015

Hi all,

I have a Cannondale Synapse Carbon 105, which is less than 6 weeks old. On the 3rd ride, the seat/seatpost started clicking/creaking when you rock back and forward on the saddle, and has been like this ever since.

I have taken it back to my LBS twice, and on the second time they found it was coming from the internal wedge seatclamp. They put some carbon grip on the seat post and clamp, which seemed to solve the problem. However, the creaking came back 20 minutes into the next ride. I repeated the process myself, putting additional carbon grip on seat and seatpost, only for creaking to come back again ~20 minutes into the next ride.

Anyone have any experience with this, specifically with a Cannondale Synapse? I've done a search and people have mentioned it could be a defective seatpost or frame? Just thought I'd ask before returning to my LBS for the third time.

Thanks

trailflow · July 2015

It could be the saddle rails where they are connected to the saddle base. Silicone lubricant spray is excellent for this and worth a try.

rawjunk · June 2016

I have this same problem and it's driving me insane. Here is a video about the noise: https://youtu.be/tT5CDVHJ5OM

I'm pretty sure it's coming from the seatpost wedge. It makes a creaking noise when you start to tighten it. I put grease between the wedge and the frame, then applied carbon assembly paste on the seattube and the seatpost but the noise comes back in 20 minutes or so. I haven't yet tighten it past 6nm, but I might need to try that.

Any ideas how to make it stop?

ayjaycee · June 2016

I had the same problem (sort of) with my 2016 Synapse Ultegra - in my case, it actually sounded like a loud cracking noise and was worrying to say the least. Like MCoolta, I tried carbon paste but, in the end, sorted it by tightening to 6NM (according to my Park Tools torque wrench which I think is accurate!) and then giving it another half turn or so - it's now been five months without any noise at all. NOTE: I will not be held responsible for the consequences of any overtightening but I personally, would give it a go were I in your position. Of course, you might also have the option of sending it back to Cannondale if the supplier couldn't sort it out for you!!!

Let us know how you get on.

rawjunk · June 2016

Thanks for the quick reply. Unfortunately my Cannondale dealer is few hundred kilometres away. I got a new carbon paste from Mucoff, so maybe I try that with going slightly past 6nm. I have a cheap torque wrench which feels very flimsy so I don't know how accurate it even is. It's also pretty annoying that Cannondale put that bolt so near the seatpost that you can't even use torque wrench without extender

ayjaycee · June 2016

Rawjunk wrote:

It's also pretty annoying that Cannondale put that bolt so near the seatpost that you can't even use torque wrench without extender

which, in the real world, is not really a problem.

rawjunk · June 2016

Did a test drive today, maybe it didn't click as often but it's still annoying me. I guess I'll ask Cannondale for advice.

I wonder could longer seatpost help, maybe take some pressure off the wedge. I'm running 350mm post now, which is about 1-2cm away from the minimum insertion mark.

Drax32 · July 2016

I had the same problem with my 2015 Synapse carbon 105 last year. My local bike shop had a look at it but didn't fix the problem.
The only way I got rid of the creak was to remove locking mechanism in the frame and grease the whole bolt and plastic locking parts with Tacx Carbon Assembly Compound ( be careful not to get it on your frame ) and tighten up to 5NM with a LifeLine Essential Torque Wrench. (Don't be tempted to over-tighten)
Every now and again I spray the top of the 4mm hex key bolt with a small amount of wd40 , no more creaks or slippage .

Hope this helps.

http://www.wiggle.co.uk/lifeline-essent ... rench-set/

http://www.chainreactioncycles.com/tacx ... lsrc=aw.ds

rawjunk · July 2016

I tried that, didn't help. I lowered my seat by 2cm and the clicks pretty much stopped. I'm gonna try 400mm seatpost next week and if that doesn't help, I'll send it to my dealer to take a look at it.

Here is how it sounds on a bad road:

https://youtu.be/UE2Mv0QzmUs
https://youtu.be/i63emHu51es

willmo · October 2017

So I finally purchased my dreambike, a new 2017 Synapse Carbon 105. On the first ride I was stopping every 2 or 3 miles to readjust the seatpost as it kept sinking. Following advise from the dealer I refreshed the carbon assembly paste on the post and lo and behold the sinking is fixed but I now have the most irritating creaking coming from the seatpost clamp. Both Cannondale and the dealer assure me that the post torque can be taken up to 9Nm even though the tech bulletin above shows 5-6Nm.

Rather oddly my bike was supplied with a 300mm post and according to the specs a 54cm frame should have a 350mm post - will this make any difference and do I go for 9Nm anyway? Recommendations from folk on the forums is that the torque can actually be reduced when the assembly paste is used. Any further thoughts on what appears to be an ongoing problem? I don't fancy torqueing the bolt up to 9, cracking the frame and then having to jump through hoops to get a new bike out of Cannondale.

ayjaycee · October 2017

As I said above, I tightened mine to the recommended torque and then added a bit more with my fingers crossed. I do get a noise every now and then but it's so infrequent that I'm not bothered about it. I'm due to give the bike a good going over prior to retiring it for the winter and I'll be taking the seat post out to clean and re-carbon paste as part of that job and will tighten using the same method, again with fingers crossed! If you are not comfortable tightening it past whatever Cannondale recommend, I suggest the only solution is to let the shop do it - that way at least they will be liable.

Out of interest, did Cannondale tell you that 9nm would be OK directly or via the dealer and did you get it in writing? If so, could you share the text of the email (or whatever) please.

ayjaycee · October 2017

PS. Sorry but I don't know whether the extra 50mm of seat post would make any difference. When I get around to taking mine out (the bike is a 56), I'll check what length it is and post again.

willmo · October 2017

My email enquiry to Cannondale in the States was referred back to Cycling Sports Group, the UK Warranty Dept for Cannondale. I have an email from them stating that "the bolt can be torqued up to 9Nm if required". I only have a torque wrench for 5 and 6Nm so it's the 6 I'll try next - 9Nm will be a last resort.
Your post should definitely be the 350mm, fitted to 54-61 sizes.
As regards letting the dealer do the post up I'm afraid that wouldn't help me as I'm still in the process of finding the correct saddle height. Perhaps when I've found the ideal height and it's still creaking I'll take the bike back.
I hadn't envisaged all this trouble from a top quality bike retailing at £1600.

rawjunk · May 2018

willmo wrote:

My email enquiry to Cannondale in the States was referred back to Cycling Sports Group, the UK Warranty Dept for Cannondale. I have an email from them stating that "the bolt can be torqued up to 9Nm if required". I only have a torque wrench for 5 and 6Nm so it's the 6 I'll try next - 9Nm will be a last resort.
Your post should definitely be the 350mm, fitted to 54-61 sizes.
As regards letting the dealer do the post up I'm afraid that wouldn't help me as I'm still in the process of finding the correct saddle height. Perhaps when I've found the ideal height and it's still creaking I'll take the bike back.
I hadn't envisaged all this trouble from a top quality bike retailing at £1600.

Did you try tightening it to 9nm? Did it help?

jgsi · May 2018

and to add insult to injury, it is a stupid proprietary seat post size.

Vino'sGhost · May 2018

JGSI wrote:

and to add insult to injury, it is a stupid proprietary seat post size.

no its not. Loads of manufacturers make a 25.4mm seat post. From the ridiculously priced enve offerings through FSA and then loads of small brands.

mrobbie · April 2019

I have this on my 2017 Synapse also... have had the seat off completely after my last few rides. Went past a bike store mid-ride today as had enough. They did the same as me - stripped, lubed, carbon grip and torqued up. Creak sorted. 10 mins later... creak back.

ayjaycee · April 2019

If it's a size 56cm, I’ll give you £100 for it.

mrobbie · April 2019

Rawjunk wrote:

I have this same problem and it's driving me insane. Here is a video about the noise: https://youtu.be/tT5CDVHJ5OM

I'm pretty sure it's coming from the seatpost wedge. It makes a creaking noise when you start to tighten it. I put grease between the wedge and the frame, then applied carbon assembly paste on the seattube and the seatpost but the noise comes back in 20 minutes or so. I haven't yet tighten it past 6nm, but I might need to try that.

Any ideas how to make it stop?

I don’t have part #1 on mine... just see the bolt head

I’ve just removed the seat post and what looks like parts #3 and #5 (the 2 metal wedge parts). Sprayed them all over with Muc Off MO94 spray, cleaned threads, wiped down, sprayed the bolt, cleaned out threads, wiped that down. Put it all back together and torqued up... NOISE GONE! (Well, for now anyway).

Will give it a coat with Muc Off Carbon Gripper tomorrow but this seems to be the cause, rather than the seat post/saddle.

...Off to remove the carbon seat post and Fizik seat from my Sigma basket

ayjaycee · April 2019

Part No.1 is a little black rubber cover that's easily lost if it's not pushed in fully. It's called a KP301 and you can buy spares for about about £6 delivered IIRC. It's a lot for what it is but I think the P&P costs more than the part itself!

Cannondale Synapse Creaking Seatpost

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