Subtle, insidious seatpost slippage on my Clem H driving me crazy

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Alex K

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Sep 9, 2021, 3:40:07 PM9/9/21
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Anybody else have issues with their seat post slipping on their Clem H or any other Rivs?  This is driving me crazy.  I am infatuated with this bike.  Favorite ride of all time.  I have a perfect 30 mile SF-Marin Headlands-SF loop that keeps me sane.    What is driving me insane however is that my seat post slips down about 1-1.5 inches every time I ride this ride, which involves quite a lot of fire trail.  I have cleaned the inside of the seat tube, I have applied friction grease, I changed the seat bolt and greased and regressed it.  I have heard that maybe a Coke can might work as a shim, but I'd rather resolve the issue without hodging and podging.  Any thoughts?  Advice?  Commiseration?  Thanks all.  I've ridden on a Kalloy and a Thomson seat post, and it doesn't matter which seat post I use, there is slippage.  
Alex

Eric Daume

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Sep 9, 2021, 3:59:06 PM9/9/21
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On my Gunnars that all featured slipping seat posts, I eventually used a Coke can shim to fix the issue.

Eric

On Thu, Sep 9, 2021 at 3:40 PM Alex K <ack...@gmail.com> wrote:
Anybody else have issues with their seat post slipping on their Clem H or any other Rivs?  This is driving me crazy.  I am infatuated with this bike.  Favorite ride of all time.  I have a perfect 30 mile SF-Marin Headlands-SF loop that keeps me sane.    What is driving me insane however is that my seat post slips down about 1-1.5 inches every time I ride this ride, which involves quite a lot of fire trail.  I have cleaned the inside of the seat tube, I have applied friction grease, I changed the seat bolt and greased and regressed it.  I have heard that maybe a Coke can might work as a shim, but I'd rather resolve the issue without hodging and podging.  Any thoughts?  Advice?  Commiseration?  Thanks all.  I've ridden on a Kalloy and a Thomson seat post, and it doesn't matter which seat post I use, there is slippage.  
Alex

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David Hallerman

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Sep 9, 2021, 4:26:03 PM9/9/21
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Could try carbon fiber paste instead of grease on seatpost, in seat tube. If you do that, be sure to clean out old grease first.

Another thought, if you have access to a knurling tool; perhaps your shop has one. That would raise a section of post that’s inside the frame.

- Dave

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Collin A

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Sep 9, 2021, 4:37:52 PM9/9/21
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You don't appreciate this 'feature' of the automatic dropper post? ;)

Yup, I had this issue occur on my 2017 Clem H with the 26.8 seatpost.

What worked, was getting the seatpost knurled by Riv (for free, just pay for shipping) OR what was later done was getting the seatpost reamed to 27.0 and using that size seatpost.

Intermediate solutions involved a layer of blue loctite on the upper 1" of seatpost insertion but it wasn't a permanent solution.

Good luck,
Collin in Sacramento

David Person

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Sep 9, 2021, 5:59:58 PM9/9/21
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As David H suggested, carbon fiber paste, or anti seize lube. It's just gritty enough to stop the slippage.

Scott McLain

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Sep 9, 2021, 7:03:01 PM9/9/21
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I like the suggestions above.  It used to be a standard practice with a new frame to take sand paper to the INSIDE of your seat tube to remove any burrs or bits that may have been left in there when they fabricated the frame.  I am sure there are people on this group that would be able to suggest the right grit emory cloth or sandpaper.  I would guess something around 200 grit.  That may provide just enough "bite" to solve your problem without defacing your seatpost.

I have also had a problem with my Albatross bars slipping down over time.  I put blue lock-tight between the bar and the stem clamp and that solved the problem.  I also had a problem with the nose of my seat wanting to creep up.  I also solved that with blue lock-tight and a little sanding on my seat post parts that were slipping.  Not sure the blue lock-tight is the right solution on the seat tube where it is dissimilar metals and it is meant to move up and down.

Scott

Patrick Moore

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Sep 9, 2021, 7:08:13 PM9/9/21
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I've had that problem with several frames, and I have used either blue
Loctite or the fiber gel developed for carbon fiber components, and
both products stopped the slipping, at least with careful tightening
of the sp collars.

On one frame with a seatpost collar instead of integrated sp clamp, I
replaced the first rather delicate clamp with a sturdier one, which
let me clamp the post with a bit more, and it turns out sufficient,
force.

I've also found that some seatposts marked as having the same diameter
are micrometrically smaller than others, enough to cause slipping in
some frames.


On Thu, Sep 9, 2021 at 1:40 PM Alex K <ack...@gmail.com> wrote:
>
> Anybody else have issues with their seat post slipping on their Clem H or any other Rivs? This is driving me crazy. I am infatuated with this bike. Favorite ride of all time. I have a perfect 30 mile SF-Marin Headlands-SF loop that keeps me sane. What is driving me insane however is that my seat post slips down about 1-1.5 inches every time I ride this ride, which involves quite a lot of fire trail. I have cleaned the inside of the seat tube, I have applied friction grease, I changed the seat bolt and greased and regressed it. I have heard that maybe a Coke can might work as a shim, but I'd rather resolve the issue without hodging and podging. Any thoughts? Advice? Commiseration? Thanks all. I've ridden on a Kalloy and a Thomson seat post, and it doesn't matter which seat post I use, there is slippage.
> Alex
>
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Patrick Moore
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Patrick Moore

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Sep 9, 2021, 7:14:00 PM9/9/21
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Re-reading this sentence, I realize that the assertion is incomplete. It may help to add that sometimes a top quality aluminum post of the same nominal diameter, like a Nitto, is just sufficiently wider to solve the problem.

On Thu, Sep 9, 2021 at 5:07 PM Patrick Moore <bert...@gmail.com> wrote:
...

Joe Bernard

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Sep 9, 2021, 11:31:20 PM9/9/21
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I had this problem with several MIT Rivs and the stock post which was solved with Nitto replacements. The problem here is the OP says he used a Thompson, too..I'll be surprised if a Nitto is nominally larger than BOTH of them. 

Joe Bernard

Nick Payne

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Sep 10, 2021, 1:55:21 AM9/10/21
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With the clamp bolt loosened, is the seatpost a good or loose fit in the seat tube? A seatpost should fit in the frame with no perceptible slop before the clamp bolt is tightened. My Appaloosa was nominally supposed to take a 26.8mm seatpost, and a 26.8mm seatpost was supplied with the frame. But the post was, I considered, too loose a fit in the seat tube, so I grabbed a 27.0mm seatpost (a Nitto S65) and did a very small amount of reaming of the seat tube to ensure a perfect fit. It's never slipped in use.

As a much cheaper alternative, you could cut yourself a shim from a coke can - the aluminium in those is usually around 0.1mm thick - and see if that makes a difference. The metal in those cans is thin enough that it can be cut with a good sharp pair of scissors. You might have to hack the initial hole in the side of the can with something else, but once you can get the scissor blade in there, it should manage the rest.

Nick

EricP

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Sep 10, 2021, 6:02:51 AM9/10/21
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Am assuming when you say you replaced the bolt, you also replaced the nut? I have found that nylock seatpost nuts don't allow me to fully torque down on the frame to hold the post.

On my Clem, a Kalloy Uno seatpost, in black, seems to not slip as much. But my issue is excess body weight, not a poor fit between post and frame. In your case, maybe a switch to a 27.0 post would be a better solution.

Good luck.

Eric Platt
St. Paul, MN

Patrick Moore

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Sep 10, 2021, 9:33:42 AM9/10/21
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I’ve found that some brands are slightly (not “nominally;” it’s a tiny but real difference) bigger than others; eg: Am Classic vs Syncro.

Patrick Moore
iPhone

On Sep 10, 2021, at 4:02 AM, EricP <eperic...@gmail.com> wrote:

Am assuming when you say you replaced the bolt, you also replaced the nut? I have found that nylock seatpost nuts don't allow me to fully torque down on the frame to hold the post.
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Garth

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Sep 10, 2021, 10:30:20 AM9/10/21
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If you want max torque to clamp the seatpost use a quick release type binder bolt. The one Riv sells is the Sunlite stainless steel version, 6x55mm, not to be confused with the other Sunlite version which just says steel and comes with steel spacers.

Alex K

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Sep 10, 2021, 11:55:57 AM9/10/21
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So much good info.  Glad I am not alone here.  Gonna reclean the seat tube and apply the Blue Friction Grease again.  Guessing it won't work, so next will be the Coke can method.  Also gonna switch to a Crystal Fellow seat post.....

 Thanks again for all the help.
Alex

Collin A

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Sep 10, 2021, 12:19:15 PM9/10/21
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Another anecdotal point...I tried the S65 in the hopes it would solve the slipping problem but it did not. The knurling on the el-cheapo kalloy that came with the Clem did, however. 

Collin, "It rained" in Sacramento

Andrew Huston

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Sep 10, 2021, 1:06:05 PM9/10/21
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My Clem H had the same issue. I called Riv and Grant told me to crank on the bolt until it doesn’t slip. He said the bolt or nut would break
Before I would damage anything. I cranked and it quit slipping. He also offered the knurling option. 

Alex K

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Sep 10, 2021, 2:24:18 PM9/10/21
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Nice.  I like that advice.  I was scared to tighten too much.  I'm not scared anymore

Ray

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Sep 10, 2021, 6:44:46 PM9/10/21
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Haha I was the one that bought Collin's Clem H from him (and eventually reamed out the seat tube like he mentioned), and before finding that solution I did in fact break the binder bolt off trying to super-tighten it. There was a lot of torque that it still slipped under before I eventually broke it.

-Ray

Craig Montgomery

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Sep 10, 2021, 11:02:36 PM9/10/21
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If you want to shim with class, head over to ACE and get a package of brass shimstock. The package has various thicknesses starting with thinnest to thickest. Start with thinnest :^) The neat thing about it is that you can wrap the post (maybe half way or a bit more), slide it in and clamp it down with excess sticking out. Then it is super easy to trim it with a delicately used Exacto or utility knife. Really a piece of cake once you get the stuff. 

Craig "Original Mickey Mouse Club member" in Tucson

On Thursday, September 9, 2021 at 12:40:07 PM UTC-7 ack...@gmail.com wrote:

Ben Mihovk

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Nov 22, 2021, 9:33:09 AM11/22/21
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I'm having the same issue on two bikes, a 2019 Atlantis with 26.8mm tube and a 2013 Sam with 27.2mm. Kalloy posts on both bikes. I reset my SH last night, marked it with a sharpie, and the sharpie mark was buried in the seat post after a my 3 mile ride. Now...I'm 210 pounds so I get that I'm going to stress that connection more than most folks. But...I unweight the saddle on rough spots and bumps and try to keep a lot of weight on the pedals.With my saddle on the bikes, if I loosen the bolt, the post sinks in. This is getting a little annoying...I popped the head off a bolt on the Sam Saturday and it scared the crap out of me (even though I knew it could happen). 

Is there anyone willing to swear by a particular friction grease to solve this issue? 

Ben, slipping in Omaha. 

Karl Wilcox

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Nov 22, 2021, 10:25:59 AM11/22/21
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I had the same seat post slippage problem with my 2018 Roadini.  I phoned Rivendell, and the chap on the phone was not very helpful.  I tried the carbon paste stuff; worked okay for a bit, but then the problem came back.  In the end, I had Chris Kelly (framebuilder in Nevada City) put the seat post on his lathe and score a pattern into the post surface.  This worked a treat-- with the scored pattern, the post stays put (it's not visible except when the seat post is out of the frame).  He did charge me 25 dollars.  Actually, I recall that Rivendell suggested scoring as a solution, but that was all.  Any one with a metal lathe can easily fix this... but I do wish that Rivendell would address this problem more proactively.
Cheers,
Karl 
Weimar, CA. 

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Ben Mihovk

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Nov 22, 2021, 10:42:33 AM11/22/21
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Thanks, Karl. I'm going to try to shim the Atlantis with a can tonight and see if it holds on my commute tomorrow. If not, I'll find someone locally who can alter the seatposts.

Ben

Patrick Moore

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Nov 22, 2021, 12:46:23 PM11/22/21
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I've had seatposts slip and fixed them in 4 ways:

1. Clamps with integrated bolt: Lots of blue Loctite, tho' I think there may be a (green?) version meant just for this.

Fiber gel meant for CF seatposts also seemed to work, but I didn't rely on that as long as I did the blue Loctite. Blue L did work, but use it liberally.

2. Separate clamps: Buy a stouter one and tighten it harder. This worked with my Chauncey Curtrivroadclone with elegant, delicate, relieved external clamp that would not tighten down hard enough -- in fact I cracked it, then bought a beefy one and that has worked fine.

3. Shim. Beer can (soda cans are not worthy of Rivendells) metal did work, but this is cheesy. 

4. Get a new seatpost (see immediately below). My ultra-expensive and ultra-light and ultra-elegant Syncro ti seatpost kept slipping, about 1/2" per mile, on one of my road bikes, and after playing with shims and Loctite I replaced it with an American Classic in aluminum that fit fine. Both 27.2 mm.

While seatpost and seattube combinations have the infinite variety of personality types and sand grains on the beach, this problem does come up often enough on this list that I'd think Riv would want to add the matter to their FAQ page.

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Ben Mihovk

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Nov 22, 2021, 1:43:06 PM11/22/21
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Thanks for the thoughts, Patrick. After talking with Will today, I'm going the knurled seat post route through Rivendell.

Ben

Patrick Moore

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Nov 22, 2021, 2:19:42 PM11/22/21
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Good luck! I've experienced seatpost slippage enough that I know the discouragement that accompanies it. 

Aside, anecdote, non-essential, FWIW, ignore safely: The last time my post slipped was on the inaugural ride of the Monocog 29er (late Oct 2020, in fact) that I'd traded onlist for an unsellable frameset. I was 3 miles in and things were not going well: the riding position, the tires, the Q, the grossly overwide bar -- all was just wrong, wrong, wrong. Add to that that it was a raw, cold day (late 2020) and the trails were half-frozen ruts mixed with just-thawed mud. And I was out of shape, and it was a grey, raw, humid, cold winter day.

So when about the 3-mile point I realized that I was now 1/2 to 1" lower than before, the sordid unpleasantness of the situation dug itself further into my brain. I stopped and raised the post, rode, slipped, stopped etc again; finally made it back home thinking, "This trade was a huge failure."

I solved the slippage with a beefier clamp, and as you've heard, after much tweaking the Monocog is now a beloved part of my 4 1/2-bike stable, and only needs a new frame and new wheelset to make it perfect. (Rear triangle to accommodate true 76 mm/3" tires with air, and new wheels to accommodate the 3" WTB Rangers without either tubes or the anxieties of "ghetto" tubeless tire installation AND that let the Rangers expand 5-10 mm more to their true potential; the OEM wheels are made of Alex 24 mm outside rims not designed for tubeless tires.)

Joe Grandia

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Nov 22, 2021, 3:09:50 PM11/22/21
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I have been suspecting the tiniest bit of slippage on my Clem H, but I have been playing with position and saddles so it has been hard to tell. I marked the seat post with a sharpie the other day to find out once and for all. I also cranked the bolt down pretty tight, so hopefully that helps. 

I had the level of slippage that you are describing on a Rawland with a Thompson seat post. A well respected bike mechanic told me to regrease the seat post and rub some dirt in it. Lo and behold, it worked! While I am sure some people are whingeing, it seemed so much more ingenious tome me than the coke can method. If there is slippage on my Clem, it will get the dirt!

Good luck,

Joe in SF

David Person

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Nov 22, 2021, 3:14:48 PM11/22/21
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"A well respected bike mechanic told me to regrease the seat post and rub some dirt in it. "

I've found anti-seize or no-seize lubricant (the stuff you are supposed to put on the treads of spark plugs when changing them) to provide the right amount of stiction to keep seat posts from slipping.

Patrick Moore

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Nov 22, 2021, 3:17:04 PM11/22/21
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Now that is indeed brilliant, in the American and also the British meanings!

Ben Mihovk

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Nov 22, 2021, 4:58:38 PM11/22/21
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Hey Joe!
That actually makes a lot of sense! Thanks!

Ben

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