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-   -   How do I keep my seatpost from slipping? (http://www.bikeforums.net/track-cycling-velodrome-racing-training-area/940870-how-do-i-keep-my-seatpost-slipping.html)

Zero Talent 03-30-14 06:58 PM

How do I keep my seatpost from slipping?
 
I was doing my first track race of the season, the cool ass mike race at encino velodrome. We were seated by flying 200. Coming out of turn 2 my seatpost slips and the nose points severely downward, i finished in 12.1. Throughout the matches it continues to slip. It is annoying me since it already has red loctite on it. The seatpost is one from the langster pro. How can I keep it from slipping because this can't happen at nationals.

queerpunk 03-30-14 07:04 PM

Why is there loctite on it? Loctite is mainly for threading. Carbon installation paste would be a much better idea. Also, grease the bolts and torque them to spec. Try that and report back.

I have a Langster Pro. No issues with the post - though I'm a featherweight.

JMR 03-30-14 07:05 PM

Quote:

Originally Posted by Zero Talent (Post 16626597)
I was doing my first track race of the season, the cool ass mike race at encino velodrome. We were seated by flying 200. Coming out of turn 2 my seatpost slips and the nose points severely downward, i finished in 12.1. Throughout the matches it continues to slip. It is annoying me since it already has red loctite on it. The seatpost is one from the langster pro. How can I keep it from slipping because this can't happen at nationals.

Carbon assembly paste and a torque wrench.

Park Tool Co. SAC-2 : SuperGrip? Carbon and Alloy Assembly Compound : Cleaning & Lube

JMR

carleton 03-30-14 07:45 PM

What bike and/or seatpost are we talking about?

Zero Talent 03-30-14 08:15 PM

Specialized Langster Pro. Venge seatpost. It's not the seatpost thats slipping downward its the nose of the saddle that is slipping. The problem is the single bolt holding it is not strong enough.

carleton 03-30-14 08:50 PM

Quote:

Originally Posted by Zero Talent (Post 16626835)
Specialized Langster Pro. Venge seatpost. It's not the seatpost thats slipping downward its the nose of the saddle that is slipping. The problem is the single bolt holding it is not strong enough.

http://s7d5.scene7.com/is/image/Specialized/10070

I hate those 1-bolt seatposts. I don't know if there is a good solution, but here's something that's worth a try: It's my understanding that the seatpost is reversible. Maybe put it in the forward position then jam your saddle all the way back in the rails, this will decrease the leverage the saddle has which is making it tilt. Hopefully, you can achieve the same setback.

queerpunk 03-31-14 06:19 AM

Ah.
Well, in which case, I blame the loctite you put on it - it is supposed to add resistance to threads turning, and may make it hard to tighten adequately!
Disassemble the whole thing, and put carbon installation paste around the whole inner cylinder of the saddle clamp assembly.
Remove the loctite from the threads of the bolt. Replace with honest, old-fashioned grease.
Torque to spec.
Live happily ever after.

Brian Ratliff 03-31-14 08:36 AM

Red loctite was a mistake. If you can get the bolt out again, find a new bolt and just use grease. Never use anything other than blue loctite if you ever want the bolt to move again.

Impreza_aL 03-31-14 12:34 PM

hairspray.

Lew. 03-31-14 03:40 PM

You guys do know that the 'saddle holding part'* of the post is alloy, not carbon?
My Langster Pro slipped once, but after that (when I started tightening it properly), it's been fine. I was too gentle with it as I thought it looked a bit brittle.

*If that thing does have a name, I can't think of it. The closest I can think of is 'saddle clamp'.

Zero Talent 03-31-14 05:40 PM

I can still tighten the bolt super tight ie 50nm. I will try the carbon paste and flipping it though. Thanks everyone.

JMR 03-31-14 05:53 PM

Quote:

Originally Posted by Lew. (Post 16629191)
You guys do know that the 'saddle holding part'* of the post is alloy, not carbon?

Yep, most assembly pastes will work on alloy too... the Park stuff I linked above specifies that it is for carbon or alloy.

JMR

carleton 03-31-14 06:01 PM

By the way, this is a known issue with that type of seatpost. I've know the Felt TK1 (older Ritchey) seatposts and the Serenity seatposts to have that problem. I've seen this design tilt under the smallest of riders.

This is why I think Felt went with the 3T seatmast topper.

MarkWW 03-31-14 09:25 PM

Those one piece bolts do require a higher torque than normal (usually 12-16 N*m), but I'm going to venture a guess if it's been torqued up to 50Nm, you'll probably want to replace that bolt. It's also possible that the conical wedge(s) slipping a few times has worn or smoothed down the mating area on the seatpost, which is making problems worse. If your shop is nearby, I would try to get them to warranty the seatpost assembly, and the next go around re-assemble with friction paste on those two surfaces and grease on the bolt threads.

Quinn8it 03-31-14 09:34 PM

Currently every bike I own is built up with a Thomson post- and it's for a very good reason. There is nothing more annoying than seat post/saddle issues, and once you think they are fixed its always in the back of your head that it still is going to happen.. And it probably will.

i wish more companies used standard post on track frames

carleton 03-31-14 10:13 PM

Quote:

Originally Posted by Quinn8it (Post 16630114)
Currently every bike I own is built up with a Thomson post- and it's for a very good reason. There is nothing more annoying than seat post/saddle issues, and once you think they are fixed its always in the back of your head that it still is going to happen.. And it probably will.

i wish more companies used standard post on track frames

You know I agree. The bike that I'm commissioning will also use a standard post (Thompson 30.9).

It pains me to see that Dolan went away from this with the DF4.

Brian Ratliff 03-31-14 10:25 PM

Quote:

Originally Posted by carleton (Post 16630214)
You know I agree. The bike that I'm commissioning will also use a standard post (Thompson 30.9).

It pains me to see that Dolan went away from this with the DF4.

The Dolan seatpost has a clamp based on the Thompson design. It is two bolts in a rocker pattern and doesn't rely on friction in any way. Since I got my Dolan Forza (similar seatpost as the new DF4 and identical clamp), I have been pleasantly surprised at the quality of the seatpost interface and the clamp. It is extremely well thought out. After two track sessions, no signs of slipping at all.

carleton 03-31-14 10:41 PM

Quote:

Originally Posted by Brian Ratliff (Post 16630249)
The Dolan seatpost has a clamp based on the Thompson design. It is two bolts in a rocker pattern and doesn't rely on friction in any way. Since I got my Dolan Forza (similar seatpost as the new DF4 and identical clamp), I have been pleasantly surprised at the quality of the seatpost interface and the clamp. It is extremely well thought out. After two track sessions, no signs of slipping at all.

Sorry. I was referring to using a non-round shaft.

JMR 03-31-14 10:54 PM

I know that they tend to work better, but seeing a beautifully shaped, aerodynamic track frame with a standard round seatpost just breaks my heart.

:)

JMR

Velocirapture 04-01-14 12:17 AM

Quote:

Originally Posted by Zero Talent (Post 16629490)
I can still tighten the bolt super tight ie 50nm. I will try the carbon paste and flipping it though. Thanks everyone.

Are you sure you are actually tightening the bolt to that enormous torque,? Maybe the torque you are applying to the bolt is possibly still not actually moving/ tightening it, due to the red loctite? Your torque wrench will show as much torque as you apply..

queerpunk 04-01-14 08:41 AM

Quote:

Originally Posted by Velocirapture (Post 16630390)
Are you sure you are actually tightening the bolt to that enormous torque,? Maybe the torque you are applying to the bolt is possibly still not actually moving/ tightening it, due to the red loctite? Your torque wrench will show as much torque as you apply..

exactly my thought. instead of actually bringing the pieces together, those 50nm could just be grinding through the loctite.

that's why we use grease on bolts. when there's a greased interface it allows pieces to move against each other, which lets them get tight enough to hold.

Quinn8it 04-01-14 10:13 AM

Pretty sure that's how babies get made also

queerpunk 04-01-14 11:11 AM

Depends on the interface used.

Soil_Sampler 04-01-14 05:31 PM

Specialized post
 
Zero issues with my Specialized seatpost.
Make sure it is assembled correctly.
http://3.bp.blogspot.com/-MYLPxcJ2iq...e+seatpost.JPG


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