worn seat post

Discuss light weight issues concerning road bikes & parts.
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sungod
Posts: 1415
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

after many removals/refits for travelling in the bike box, my ax daedalus has become a bit slippy at the max clamp bolt torque i am comfortable with using, losing maybe 0.5-1mm each ride

i've always used carbon paste, but with the many insertions i think this has gradually worn off the surface coating - the label is completely worn off now - it also feels a bit easier to fit/remove than it used to be (frame is xcr steel)

two options i am thinking of...

put a strip of kapton tape down one side, it's thin c. 0.05mm, tough, the silicone adhesive is very stable, also should be easy to redo once it gets worn - plus i have an old reel of it!

re-coat the post, but with what? it needs to be something tough enough to withstand repeated insertions, not too thick, not go sticky and jam the post

any opinion or other ideas for long term solution?

by Weenie


sp3000
Posts: 173
Joined: Thu Aug 21, 2014 7:12 am
Location: Sydney

by sp3000

The tape sounds like a fine idea. The ax posts are just hand polished, you could if you liked spray the inserted section with a clear coat to add a bit of thickness that wouldn't cause any gripping issues and might protect it more from future removals/insertions.


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sungod
Posts: 1415
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

tape didn't work, it was being sheared off as the post was inserted

i got some clearcoat u-pol up0804 (amazon in the uk)

masked off the post just above the point where it'd emerge from the seat tube, careful degrease and then dusted on two thin coats, left it to dry for a couple of days

the finish is very smooth

applied some assembly paste, it felt tighter inserting it, there was no sign of the coating being shaved off though i'll only be able to check properly next time i remove it for packing

torqued to the usual level, only had one ride on it but so far no more slipping :)

TheKaiser
Posts: 436
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

sungod wrote:torqued to the usual level, only had one ride on it but so far no more slipping :)


Congratulations on the successful fix, and thanks for the tip. That might come in handy in the future. I was also going to add that carbon assembly paste varies quite a bit in particle size from brand to brand. For instance, the Tacx if have seen was very fine, whereas the Park is quite gritty. Depending on which one you were using, stepping up to a more aggressive one might help too, but obviously your fix is better as with more aggressive paste eventually your post would be worn further.

youngs_modulus
Posts: 507
Joined: Wed Sep 20, 2006 1:03 am
Location: Madison, WI USA

by youngs_modulus

sungod wrote:tape didn't work, it was being sheared off as the post was inserted

i got some clearcoat u-pol up0804 (amazon in the uk)

only had one ride on it but so far no more slipping :)



Solving your own problem? Well done.

Geeky side note: there's a reason why the clearcoat worked and the tape sheared off: the tape was about twice as thick. Your Kapton tape may have been only 50 microns, but the silicone adhesive alone is another 40 microns. Clear coats are about 35-50 microns--much thinner than the tape+adhesive.

sungod
Posts: 1415
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

TheKaiser wrote:
sungod wrote:torqued to the usual level, only had one ride on it but so far no more slipping :)


Congratulations on the successful fix, and thanks for the tip. That might come in handy in the future. I was also going to add that carbon assembly paste varies quite a bit in particle size from brand to brand. For instance, the Tacx if have seen was very fine, whereas the Park is quite gritty. Depending on which one you were using, stepping up to a more aggressive one might help too, but obviously your fix is better as with more aggressive paste eventually your post would be worn further.


for several years i've used a mix of tacx paste and the grittier finish line paste, i'd found this more effective than either on it's own

not tried the park tool one though

fwiw i found the morgan blue paste was worse than useless, it was more like a lubricant

by Weenie


srshaw
Posts: 152
Joined: Sun Apr 05, 2015 6:06 pm

by srshaw

I successfully used some very thin sellotape to 'shim' a seat post. The trick was to have it run vertically with it folded under at the lower end. This way it didn't just get ripped of as I inserted the post.

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