Seatpost slipping down no matter what

[PanoIgano]

Hi guys,

Anyone with advice of what to do when a seatpost keeps slipping down?

Is there any thread in the forum on this cause I couldn’t find one.

Tried a few tricks I found online like greasing the bolt of the seat collar and drying the seat tube and seat post of any grease but still no luck.

I have been trying to tighten as much as I can the seatpost clamp but still no luck.

Thanks in advance!
Panos

 

[Fourbikes]

I've had slipping seatposts in the past. I used a torque wrench to tighten the clamp (nut and bolt, not quick release), and if it still slipped, I tightened slightly more the next time. I found it needed around 15nm for it to stay in position on one of my bikes. That was on a steel frame with an alloy seatpost. It does vary from bike to bike. Also depends on your weight I should imagine (I'm relatively light at 75kg). Need to make sure it's the right size as well.

 

[bikeworkshop]

Insert the post 100mm with clamp loose, then see if there's any waggle by moving the top of the post fore/aft. If so, how many mm?

Post a photo of the clamp bolt area.

Constantly slipping post is usually either a poor fit or a stretched collar.

 

[PanoIgano]

I am 67kg so I think my weight is not an issue.

So the frame is steel and the post aluminum and I am using a quick release. That's the clamp the bike came with.

Will upload a picture tonight.

 

[hamster]

I agree with @bikeworkshop - often bikes leave the factory with an ill-fitting post, often even the post dimensions are wrong or sloppily toleranced. The waggle test is a good starting point.

 

[FZRIP]

I’ve used gripper paste with success on one frame. Steel frame alloy post.

 

[madjh]

Put one of this light adapters. You will have light and never ever will slip, even without the lock. They have a rubber and works quite well. Avoid cheap chinese ones. Cat eye etc are the best ones.

 

[PanoIgano]

Insert the post 100mm with clamp loose, then see if there's any waggle by moving the top of the post fore/aft. If so, how many mm?

Post a photo of the clamp bolt area.

Constantly slipping post is usually either a poor fit or a stretched collar.

 

[hamster]

Hmm, external cam QRs really don't allow you to apply that much force. I would try a bolt across that collar first to see - once the waggle test is done.

 

[bikeworkshop]

Collar shape looks ok although the 5mm bolt won't provide much clamping force.
Cam shape affects leverage to tension ratio. Some cams can provide more tension than an Allen head bolt, many do not, especially those crappy ones that sit in a plastic bucket washer.