RubenVogels

Hello mechanics! I have a 2020 carbon Giant Revolt Advanced 2, with the infamous D-fuse system. The bike rides fantastically provided the seat post doesn't drop down.... Which unfortunately does happen every time lately. I have not yet contacted Giant and first wanted to see if I could learn some trics via this forum to solve the problem. I have tried all the known greases but still have a sinking seatpost.

I look forward to your response and hope there is a definitive solution!

pinsonp2 

Have you tried something like Finish Line Fiber Grip Paste?

RubenVogels

Yes right I have indeed tried three different variants including this one. But it keeps coming back.

J.Higgins 

Ruben, have you tried cleaning the seatpost very well, perhaps using some mineral spirits? Twist up a metal coat hanger to resemble a giant needle's-eye, and insert a piece of cloth and use that contraption to swab it all out nice and clean, and start fresh. This technique has worked for me quite a lot, and has become my standard operating procedure for any carbon bike that comes into my inventory. Maybe this will work for you.

RubenVogels

I did clean it with a cloth but nothing like you describe. Going to try it tomorrow right away. Thanks!

However, because the seatpost has sunk down so many times, I can also imagine that the scratches this has caused on the seatpost do not contribute to the grip on the clamp or the frame....

veloz

Fibergrip paste & torque wrench. Visit your dealer if still an issue. They’ll likely be happy to take care of it.

RubenVogels

Fibergrip paste and torque wrench are already applied but did not help..

TiHabanero

If the seat collar is a two bolt, I pity you. Clean out seat tube and seat post, grip paste and then tighten. Have patience and be persistent. We had one where we had to over size the holes in the seat collar and put a bolt/nut arrangement in to provide enough clamping force to hold the post correctly.
Keep in mind the collar is the clamp and the slit in the seat tube allows the collar to pinch the frame and bind on the post.. Below the collar there is no clamping being done, however adding paste below the collar may assist in preventing seat post movement. Also be careful with over torque on the bolts as the carbon can crack. We ended torque at 8nm to get the thing to hold. It is rated at 6nm on the collar.

My apologies for this post as it has nothing to do with the wedge binder used on your frame!

Crankycrank

I can't remember where I heard this from but one person with the same problem mentioned that his DF clamp had a 3 piece wedge system and he just used some light grease on the wedge clamp surfaces where they contacted each other allowing them to move freely and put a little stronger and even pressure between them.

Eric1970

I had to file down my seat clamp as it wasn’t closing enough to keep it tight

easyupbug 

Been there, had valve grinding compound in the shop and it worked great but is too inexpensive for cycling.

FlubbyHanger

Did you find a solution to the slipping seat post?
I've been going crazy because of this problem. Even after the mechanic coated every possible surface with grip-sand (to the point it's almost impossible to manually insert the seat); still.. still it sinks. I notice the primary reason it sinks seems related to how the metal plate in back interacts with the post whenever there is flexing. It's like the metal plate creates a slip-zone and with every tiny bounce of the seat it works it's way down. I'm super frustrated by this; is there any hope??

icemilkcoffee 

My standard answer for all slipping seatpost threads: rack mount clamp

They even make one for the D-fuse seatpost.

_ForceD_

I’m not familiar with the seat post system in the OP. But if the binder has more than one bolt…I think you have to make sure they are both torqued sufficiently AND EVENLY. My CF Specialized Venge has an aero seat post with two binder bolts. Although the bolts were torqued to spec, I was having the same slippage issues that even the grip paste wouldn’t solve. Finally…although both bolts were torqued to specs…they weren’t even. The space on one side of the clamp was wider than the other one. Once I loosened, re-clamped them with even spacing, and torqued to spec the problem went away.

Dan

MudPie

This is generally great advice on any multi-fastener system: chainrings, disc rotors, handlebar faceplate, automobile wheel lug nuts... This helps ensure the fasteners are equally loaded and minimizes warping of the components. And if the fasteners are in a pattern, I'll progress in a star-type patterns, where opposite fasteners are tightened in sequence.

I may to thru three or four iterations of increasing tightness until I reach final torque. For example, I'll do "finger tight", then "tool tight using fingers" then "tool tight using palm" then final "torque wrench tight"