Carbon Seat Post Slipping

[cool_hand]

Titanium Road Bike - 27.2mm seatpost.
Using an OEM carbon post that came off an older bike.
I've mounted a rear reflector onto the post which I'm using as a mark for adjusting the seat higher.
Finish Line Fibre Grip + 7 nm however post is gradually slipping down to the reflector band each time I test ride the bike to check the new saddle height.
I guess one option would be to move the reflector band down to stop the post slipping but would prefer a working solution without using the band.
Is the seat clamp the issue, how high can I torque a carbon post? What am I doing wrong?

 

[vickster]

Try a new seatpost clamp. When I got my Sabbath, the Ti post was slipping. A new clamp (and unscathed replacement post) solved the issue. I’m not convinced that carbon posts are a good thing in any frame material myself!

 

[cool_hand]

I still have the original alloy post (and saddle) that came with the bike and the difference in weight without removing the saddles is 125 grams. The alloy post is about 11cm longer which probably accounts for the weight. I thought carbon offers some compliance but if it slips it's useless. I guess I could just revert to using the reflector clamp to secure it. I guess the clamps are pretty much all the same?

 

[vickster]

I still have the original alloy post (and saddle) that came with the bike and the difference in weight without removing the saddles is 125 grams. The alloy post is about 11cm longer which probably accounts for the weight. I thought carbon offers some compliance but if it slips it's useless. I guess I could just revert to using the reflector clamp to secure it. I guess the clamps are pretty much all the same?

125g is nothing In the general scheme of bike plus adult rider unless you're a pro looking for marginal gains, and if you were you wouldn’t have a Ti bike in the first place. Not sure how a carbon seat post is more compliant, isn't it a stiffer material? Ti is nice and springy though and comes as seat posts (see avatar <<)

 

[Red17]

You could try some carbon assembly paste. I used some to stop an alloy post slipping in a carbon frame and it solved the issue
.

 

[figbat]

The alloy post is about 11cm longer which probably accounts for the weight...

...and probably contributes to the slipping tendency. A longer insertion length will offer more friction and less slip ().

 

[cool_hand]

125g is nothing In the general scheme of bike plus adult rider unless you're a pro looking for marginal gains, and if you were you wouldn’t have a Ti bike in the first place. Not sure how a carbon seat post is more compliant, isn't it a stiffer material? Ti is nice and springy though and comes as seat posts (see avatar <<)

Sorry, I wasn't trying to suggest I was after marginal gains - I think the issue could be down to the length of the carbon post, it's only 20 cm. A Ti seatpost sounds like a good suggestion. Had a look at your Avatar - what brand of seat-bag do you use?

You could try some carbon assembly paste. I used some to stop an alloy post slipping in a carbon frame and it solved the issue
.

Isn't that what I've already been using (Finish Line Fibre Grip) - or is assembly paste different to fibre grip?

...and probably contributes to the slipping tendency. A longer insertion length will offer more friction and less slip ().

I just swapped the posts over - put the longer alloy post in and it doesn't slip.

 

[Cycleops]

...and probably contributes to the slipping tendency. A longer insertion length will offer more friction and less slip ().

As the actress said to the Archbishop.

 

[bobzmyunkle]

I had the same problem. Carbon paste seemed to work for a while and then seemed to dry out and the slipping started again.
I added one of these https://www.bikeparts.co.uk/products/m-part-elite-seatpost-memory-lock-ring-31-6-mm-1# works perfectly

 

[cool_hand]

I had the same problem. Carbon paste seemed to work for a while and then seemed to dry out and the slipping started again.
I added one of these https://www.bikeparts.co.uk/products/m-part-elite-seatpost-memory-lock-ring-31-6-mm-1# works perfectly

What is the Memory Lock Ring made out of?
This looks like it will function the same as using the rear reflector as an anchor.

 

[Big John]

I had an alloy seatpost in a steel frame that slipped like buggery. There was no seat clamp, just a bolted 'slot'.....I'm sure you know what I mean. I tightened it until it was impossible to tighten it any more and still it slipped down over time. In the end I used an ordinary jubilee clip (this was my 'pub' bike so I wasn't overly worried about how it looked) and it worked a treat. Now I'm not suggesting you use a jubilee clip.....just saying 😄. It's still on my bike after about ten years.

 

[bobzmyunkle]

This looks like it will function the same as using the rear reflector as an anchor.

That would probably work the same. The lock rings just a lot tidier in my opinion,

 

[boydj]

Try something like this https://www.tredz.co.uk/.Fenwicks-Professional-Carbon-Assembly-Paste_101992.htm

 

[Kingfisher101]

Moving the reflector band down wont stop the seat post slipping, it will just get pushed upwards.
I had this and used carbon paste and aligned the clamp with the cut-out on the seat tube and all is now well. It drove me mad.

 

[vickster]

Sorry, I wasn't trying to suggest I was after marginal gains - I think the issue could be down to the length of the carbon post, it's only 20 cm. A Ti seatpost sounds like a good suggestion. Had a look at your Avatar - what brand of seat-bag do you use?

None any more, that photo was pre rack and pack. Can’t get a d-lock in a seatpost bag, useless!
However, I think that’s a large Specialized one, a Wedgie had for years, no longer made
https://www.sigmasports.com/item/Specialized/Wedgie-Saddle-Bag/2W69