HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Articles FAQ Contact About




Post new topic Reply to topic  [ 20 posts ] 
Go to page 1, 2  Next
Author Message
PostPosted: Mon Dec 23, 2013 5:31 am 
Offline

Joined: Sat Sep 03, 2005 12:14 pm
Posts: 94
Location: Residing in Europe
First of all, everything stated here is brand new, no pre-owned condition.

Of late, I have been experiencing slippage during each ride, despite effort to tighten the Mcfk seat-clamp with seatpost before each ride. [I am using torque wrench and are worried if I uses too much strength on the clamp, it will gives way.]
I weighed myself, and only gain few hundred grams. :oops: :oops:

[I don't even need to tighten each time for my other bike, and both bikes are usually in cruising speed.]

Have anyone using Mcfk 3K seatpost with its seat-clamp, and experienced similiar situation? (or not experiencing anything??)
What is your workaround solution? [buying another seatpost seem viable option, I keep them in mind]


Top
 Profile  
 
Posted: Mon Dec 23, 2013 5:31 am 


Top
  
 
PostPosted: Mon Dec 23, 2013 6:21 am 
Offline

Joined: Tue Jan 22, 2013 6:23 am
Posts: 352
I'd measure the seatpost to make sure it is the correct size (not just the correct number stamped on it). I had a 27.2 Easton Seatpost that measured 27.08mm and it kept slipping. I bought a Thomson and it measured in at 27.19mm and worked great. The seatpost needs to be the perfect size because the seatpost clamp needs to apply pressure over a larger area (flat all the way around). If the seatpost is too small or frame is too large the seatpost clamp will try to bend in grab around the top resulting in very little surface area to grab.

Good luck!


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 6:34 am 
Offline

Joined: Sat Sep 03, 2005 12:14 pm
Posts: 94
Location: Residing in Europe
I should have been more forthcoming about this problem, leaving much to speculate.
I have measured the bike frame and confirmed with its manufacturer, it is indeed 27.2mm in diameter.
Also I seek clarification from bikeshop before I placed the $$ to them for seatpost and clamp, so I am safe too.

Do you reckon I would need a shim?
Could it be the clamp was not tighten enough, leaving much room to slip?

This is dampening the christmas spirit.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 6:57 am 
Offline

Joined: Tue Sep 14, 2010 3:28 pm
Posts: 1402
Have you used assembly compound?
Image


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 7:27 am 
Offline

Joined: Tue Jan 22, 2013 6:23 am
Posts: 352
Limbo wrote:
I should have been more forthcoming about this problem, leaving much to speculate.
I have measured the bike frame and confirmed with its manufacturer, it is indeed 27.2mm in diameter.
Also I seek clarification from bikeshop before I placed the $$ to them for seatpost and clamp, so I am safe too.

Do you reckon I would need a shim?
Could it be the clamp was not tighten enough, leaving much room to slip?

This is dampening the christmas spirit.



I would measure both yourself if possible. Just because it says 27.2mm doesn't mean that it is. Manufacturing defects can occur and I'm pretty sure the bike shop didn't measure the post to ensure it's accuracy. They usually just look at what's labeled and ship.

Most clamps are 6-8nm in torque from what I've seen. You bike should have a recommended torque for the seatpost clamp and it should be plenty of force. I don't think tightening it is an issue, it doesn't take a ton of torque to keep the seatpost tight.

I've seen people with the same issue use a soda can to make a shim. It would be a cheap way to try it out. It would be best if you could try another post to ensure it is specific to your new post.


Oh and carbon assembly paste does not prevent things from slipping. It prevents carbon from galvanic corrosion. It may help slow down the slipping but it is not something I would rely on.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 8:19 am 
Offline

Joined: Thu Jan 08, 2004 10:11 pm
Posts: 707
My BMC frame says 5nm and setting it at 5nm with a torque wrench left a serious clamping mark in the BMC seatpost :'( So I only use 4nm now in combination with the Tacx paste. I also wrapped a bit of tape around the post just above the clamp and it doesn't slip at all.

So it really depends on frame.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 8:33 am 
Offline

Joined: Sat Nov 10, 2007 9:51 pm
Posts: 293
bricky21 wrote:
Have you used assembly compound?
Image


+1 I definitely try some carbon assembly paste, it will increase the friction between the seat post and seat tube allowing you to use less force on the clamp.

Tacx Carbon Assembly Compound, FSA Installation Compound and Finish Line Fiber Grip are good products

The FSA comes in small packs, which is probably more than you need for a seatpost/ seat tube and stem/ handle bar interfaces.

http://www.trisports.com/fsa-installati ... paste.html


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 8:40 am 
Offline

Joined: Tue Sep 14, 2010 3:28 pm
Posts: 1402
bombertodd wrote:
Oh and carbon assembly paste does not prevent things from slipping. It prevents carbon from galvanic corrosion. It may help slow down the slipping but it is not something I would rely on.

Image
Thats some deceptive advertising then I guess. Lots of people use some sort of Carbon Assembly Compound to keep there parts from slipping.

Some carbon handlebars even come with it. I just assumed that it was because people were over tightening their bars to keep them from slipping :noidea: I was never aware that anodized stems corroding away from being in contact with clear coated carbon fiber was a real concern.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 8:59 am 
Offline

Joined: Tue Sep 14, 2010 3:28 pm
Posts: 1402
The seat clamp may also be the problem. I've not had good luck with WW carbon fiber seat clamps.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 9:23 am 
Offline

Joined: Tue Jan 22, 2013 6:23 am
Posts: 352
bricky21 wrote:
Thats some deceptive advertising then I guess. Lots of people use some sort of Carbon Assembly Compound to keep there parts from slipping.



I too use carbon assembly paste (actually the same exact stuff in your picture) when the manufacturer calls for it. However I don't think it should be relied upon to hold things together. In my same experience as the OP with one of my bikes I tried all the way up to 12nm of torque and carbon paste out of sheer frustration. It just made the post slide down slower. I don't doubt that the paste will lower torque requirements in a mechanically sound setup, but that is most likely the issue, it's not mechanically sound. Unfortunately parts have tolerances. It is possible that the post is at the smallest end of its tolerance and the frame is the highest end of its tolerance. This leaves a too large of gap between seat post and frame. I don't know what the tolerances of each item are but I suspect that it is the issue, or one of the pieces is too far out (past tolerance) and not caught by quality control. I don't know how tight the seatpost/seat tube tolerances need to be to keep the post up either. But it is a simple system. When two parts seem to be the right sizes it doesn't take a lot of torque to keep the seatpost from slipping.

I still think the best method is measure the seatpost and inside the frame with a pair calipers and see what the difference is. Second I'd see if a friend has another seat post you could try and see if it stays up. If so I'd measure that seatpost to see if it differs from yours. If neither stays up, it could be a frame or seat clamp issue.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 11:46 am 
Offline
Administrator
User avatar

Joined: Sat Jun 19, 2004 11:08 am
Posts: 6778
Location: Urbana, Illinois
When in doubt measure twice. Even if not in doubt measure twice. I have a Mcfk 31.6mm setback post in my Lynskey R320. I did use the Tacx carbon paste but my seat clamp of choice is the New Ultimate torqued to 4.5 nm. It has never slipped.
Image

_________________
-For my next trick I will set myself on fire!
-This board and the world in general would be a much nicer place if everyone could just take themselves a little less seriously.
-Sticky Fingers John Rockefeller
-First one over the cliff wins!


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 1:06 pm 
Offline

Joined: Thu Apr 12, 2012 4:33 am
Posts: 216
I have a mcfk clamp and used it with ax lightness post and it held at 4nm. I'd try putting a cloth tape around the post and then clamping personally. I agree you probably got two ends of the extreme which is creating tightening issues.

I once bought a brand new dogma 2 where the seatpost was too big for the seat tube and the bike shop didn't believe me when I told them it didn't fit until it was returned to them.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 4:51 pm 
Offline

Joined: Sat Apr 22, 2006 12:38 am
Posts: 1716
Location: Dutchess County, NY
I'd still use the carbon paste to see if that solves the problem.

_________________
Speedplay is the devil, Specialized is making their way to taking that title, however.


Top
 Profile  
 
PostPosted: Mon Dec 23, 2013 5:11 pm 
Offline
User avatar

Joined: Wed Jan 19, 2011 11:14 am
Posts: 1199
Sounds like something is not the right size and bombertodd you are kidding right.. It almost certainly does contain grit that does reduce the required torque to clamp items that are actually the right size in the first place... :noidea:


For the record I have own and have installed a number of trouble free mcfk seat posts

_________________
project black


Top
 Profile  
 
Posted: Mon Dec 23, 2013 5:11 pm 


Top
  
 
PostPosted: Mon Dec 23, 2013 7:21 pm 
Offline

Joined: Tue Jan 22, 2013 6:23 am
Posts: 352
sugarkane wrote:
Sounds like something is not the right size and bombertodd you are kidding right.. It almost certainly does contain grit that does reduce the required torque to clamp items that are actually the right size in the first place... :noidea:


I think me words above might be confusing. If the post is slipping I don't believe using carbon paste will magically make it go away. I use carbon paste (Finishline to be exact) and I do believe less torque is required when using it because of the grit. So if the seatpost will stay put with a given amount of torque the carbon paste will allow it to stay put with a little less torque (good for long term use of WW clamps and posts). But what I meant above is that if a post is slipping with max torque (per bike/clamp) adding carbon paste will not fix the slipping issue. There is plenty of torque which leads to a surface area mating issue. Something is not right (frame, clamp, post).

Quote:
For the record I have own and have installed a number of trouble free mcfk seat posts


I'm sure these are good posts but even the best of companies can have manufacturing defects such as being too small of a diameter. Or it could be the frame. It's hard to diagnose over the internet, but a pair of calipers should be able to eliminate some of the variables.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ] 
Go to page 1, 2  Next


Who is online

Users browsing this forum: BdaGhisallo, Bing [Bot], colster, fatchance1973, jb, khopin, micropox and 67 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. Mcfk seatpost - positive experience

in Road

tantra

11

1307

Mon Apr 21, 2014 6:05 pm

coloclimber View the latest post

There are no new unread posts for this topic. Colnago C59 Seat clamp torque

in Road

TimW

2

341

Wed Jan 15, 2014 6:19 pm

carbonLORD View the latest post

There are no new unread posts for this topic. Lightweight seatpost clamp

in Road

vitriol

10

1307

Wed Oct 02, 2013 1:43 pm

Ceebers1 View the latest post

There are no new unread posts for this topic. Bontrager seatpost rotary clamp/ears (+SLR carbon rails)

in Road

sanrensho

4

234

Thu May 29, 2014 8:11 pm

sanrensho View the latest post

There are no new unread posts for this topic. MCFK Stem

[ Go to page: 1, 2 ]

in Road

elfuinha

27

3184

Sat Aug 23, 2014 6:08 am

climber8 View the latest post


It is currently Mon Sep 01, 2014 1:25 pm

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB