How to prevent Saddle slip. Need some advice here

[Bateleur1]

What brand bike is it?

 

Will you be able to sit on the top tube if the saddle is out of position during a ride?

 

 

 

It is the one brand where you should not be doing it 

[Mongoose!]

 

It is the one brand where you should not be doing it

[Mongoose!]

double post

[Mongoose!]

hahaha.

[RobertWhitehead]

O wait, I forgot to mention what I discovered, this may resolve the issue you have as well: 

 

I had a carbon 29er which had an alu seat post (or whatever the material it is - it wasn't carbon like the frame  ) So I applied carbon paste to said seat post and had no issue whilst in use. I then stripped the bike and sold the frame but long story short, I used the same seat post on an older bike whilst building a dual sus. This bike was a normal, run of the mill alu frame with said alu seat post. 

 

Initially I left the carbon paste on the seat post (don't really know why, maybe for extra lubrication - don't know). The result was that my saddle kept dropping no matter how tight I made the clamp, so I removed the paste and it kept on dropping for a few rides until the paste was off the post completely.

 

I'm not saying that this will resolve your issue but just a side note: carbon paste makes alu on alu slip 

[Bateleur1]

O wait, I forgot to mention what I discovered, this may resolve the issue you have as well: 

 

I had a carbon 29er which had an alu seat post (or whatever the material it is - it wasn't carbon like the frame  ) So I applied carbon paste to said seat post and had no issue whilst in use. I then stripped the bike and sold the frame but long story short, I used the same seat post on an older bike whilst building a dual sus. This bike was a normal, run of the mill alu frame with said alu seat post. 

 

Initially I left the carbon paste on the seat post (don't really know why, maybe for extra lubrication - don't know). The result was that my saddle kept dropping no matter how tight I made the clamp, so I removed the paste and it kept on dropping for a few rides until the paste was off the post completely.

 

I'm not saying that this will resolve your issue but just a side note: carbon paste makes alu on alu slip 

 

What you describing is a seatpost slipping down.  Seatpost is fine with me.  It is the saddle slipping backwards.

[RobertWhitehead]

Correct yes, but you mentioned that you applied carbon paste to the rails  . 

 

What you describing is a seatpost slipping down.  Seatpost is fine with me.  It is the saddle slipping backwards.

[dasilvarsa]

If the paint has come off on the seat post or saddle rails.

Repaint the affected surfaces.

[jdwet1980]

Tighten bolts a bit more. Roughen rail contact points with emery paper.

Go ride....

[Bateleur1]

It finally seems I might have found the cause on the problem.  It looks like one of the two bolts might actually be comming slightly loose.  Had the problem on the weekend again and I know for sure both bolts were tightened pretty well just before the ride.  So will start with Loctite on the bolts first.  Will report back later in the week.  There will be no riding in the next day or two for sure.

[DJR]

It finally seems I might have found the cause on the problem.  It looks like one of the two bolts might actually be comming slightly loose.  Had the problem on the weekend again and I know for sure both bolts were tightened pretty well just before the ride.  So will start with Loctite on the bolts first.  Will report back later in the week.  There will be no riding in the next day or two for sure.

I think you have found it: If something starts out tight and then, after some vibration and cyclic forces (you riding) moves, it is quite possible that a bolt moved. A drop of Locktite blue on the thread (and perhaps a tad more torque) should solve the problem if we are right.