Saddle slide back

[Maherees]

Hello,
During a ride my saddle will slide back, no matter how much I tighten it. I do not want to change seatpost as it's a nice carbon thing.
Thanks.

 

[bikingdad90]

What torque do you have the bolt set to? It should be torqued to about 8/9nm’s which is tighter than stem bolts.

Is there any grease on the rails which could be causing it to slide?

Have you got the correct clamp type, there are clamps for square, clamps for oval and clamps for oversize rails?

 

[Cycleops]

You could try some carbon paste but why not get some fine wet&dry sand paper, glue two small pieces back to back and wrap the rails?

 

[Maherees]

Thanks for the ideas, i suppose i was hoping that might be some sort of bold type clamps that could be added to stop the movement but i'll try the tape first.

 

[silva]

From what I can see on the pic (not sure), the clamp looks like having a bolt on just one side, that's a weak design due to wrong side of leverage - the bolts force should be leveraged to the clamping surface, not vice versa. Also, with just on one side, you get a friction concentration - wear, near the bolt head at an edge, that gets worser.
A clamp with a bolt on each side doesn't suffer this.

,

 

[Ajax Bay]

the clamp looks like having a bolt on just one side

Each of the two elements of that clamp has a bolt (front one hidden in the image, head recessed in post). It's a Deda Superleggero carbon 25mm setback post.
Deda describe the clamp as a single bolt but really it's two: one at the front to set the saddle angle and one at the back to tighten everything up. Once you have your saddle angle set, you can remove the saddle using just the one bolt, although it's actually easier if you undo both (but you then have to reset the seat angle when refitting).

 

[silva]

Each of the two elements of that clamp has a bolt (front one hidden in the image, head recessed in post). It's a Deda Superleggero carbon 25mm setback post.
Deda describe the clamp as a single bolt but really it's two: one at the front to set the saddle angle and one at the back to tighten everything up. Once you have your saddle angle set, you can remove the saddle using just the one bolt, although it's actually easier if you undo both (but you then have to reset the seat angle when refitting).

I was talking about the front clamp/side alone, in the given picture. The single rail (there is a second one at the back).
On that single rail, below, there is a bolt head visible, bolt going to a black (metal) part.
Above it, faced away, a red (plastic?) pad, with some pin going through the black metal part.
This way, the clamp on that single rail, exercises a leveraged force on the bolt head, or in other words, the bolt needs to be tensioned more to result in a same clamping force.
With two bolts, on this single rail clamp side, it would clamp stronger and thus slip harder / stay more in place.
Alternative, a hole drilled through the center of what is clamped on, but this is no option here, due to the small section of the rail.

 

[Jenkins]

I don't know if it's the shadows, but the part of the rear clamp (the one with the bolt showing) that sits above the saddle rails appears to be sitting higher and possibly therefore grippping less than the front clamp. If you look closely the front one, the top looks to slightly cover the top of the number 6 and the division marker before the number 7, while the rear one seems to be sitting above the number 2 and clearing the division marker.

Is it all seated(!) and tightened correctly - as above with the clamp and seat rails being metal, you should be at about 8n/ms

 

[Chislenko]

Have you considered cycling with a kettle strapped to your head. The action of keeping the kettle upright will stop you pushing back in the seat this stopping the seat from sliding back.

Alternatively take two pieces of black (or white) pudding and wrap them around the seat rails, with a circular motion, the white fatty bits contained within the black (or white) pudding contain a substance scientifically proven to stop cycle saddle rail slippage.

If neither of the above works go to B&Q and spend a day looking at people looking at DIY items whilst berating their other half for their apparent lack of knowledge.

If none of the above solve the issue buy a hyena.

 

[Maherees]

Well I tried most of the recommendations except the kettle one, and still it slipped back. I think the actual clamp is just weak as the recessed front screw constantly loosens. In light of that I was wondering if you can just buy a clamp. If not I'll have to get another carbon post.

 

[Ajax Bay]

Well I tried most of the recommendations except the kettle one, and still it slipped back. I think the actual clamp is just weak as the recessed front screw constantly loosens. In light of that I was wondering if you can just buy a clamp. If not I'll have to get another carbon post.

Now that you've zeroed in on the cause, might be worth considering a serrated washer: something like this:
https://www.tcfixings.co.uk/product/m6-a4-internal-serrated-shakeproof-washer-din-6798-j/9926?
I don't know the bolt size but this is for a 6mm screw. Obviously its outside diameter would need to be small enough to fit into the seatpost 'slot' and not risk damaging the carbon.
Why would you "have to get another carbon post"? Is this a weight weenie issue?
The Al post Deda make costs <£40 as opposed to £200 for the carbon one in image ^^ It weighs 333g v 175g (350mm length).
A friend's carbon seatpost (I have one too, fitted to my Brooks to save combined weight ) sheared off at Thirsk, 1000km into and on D4 of his LEL: ruined his day/ride/year. He has wiped the incident from his memory, however his friends keep a Remembrall handy for pub use (see also disc brake pads, gouged chainstay, RD, crashes).

 

[ebikeerwidnes]

Would it be possible to trim off a bit of old inner tube and wrap it around
the bar then tighten the bolts onto it?

 

[Cycleops]

@Maherees says it's the retaining bolt that is constantly loosening so what about using some thread look?

 

[Maherees]

Now that you've zeroed in on the cause, might be worth considering a serrated washer: something like this:
https://www.tcfixings.co.uk/product/m6-a4-internal-serrated-shakeproof-washer-din-6798-j/9926?
I don't know the bolt size but this is for a 6mm screw. Obviously its outside diameter would need to be small enough to fit into the seatpost 'slot' and not risk damaging the carbon.
Why would you "have to get another carbon post"? Is this a weight weenie issue?
The Al post Deda make costs <£40 as opposed to £200 for the carbon one in image ^^ It weighs 333g v 175g (350mm length).
A friend's carbon seatpost (I have one too, fitted to my Brooks to save combined weight ) sheared off at Thirsk, 1000km into and on D4 of his LEL: ruined his day/ride/year. He has wiped the incident from his memory, however his friends keep a Remembrall handy for pub use (see also disc brake pads, gouged chainstay, RD, crashes).

I have noticed quite a difference on low level road 'rumble' vibration - of course this might be my imagination. Not a weight weensy not when your nearly 16 stone! Ideally as the bike is titanium id get the same material but they're are hideously expensive.