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Old 09-29-05, 05:38 AM   #1
FarHorizon
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Single bolt vs double bolt seatposts?

Ere it just my imiganition, or do one-bolt seat posts not "hold" as well as two-bolt ones? On two of my bikes, I've used one-bolt seat posts (one post a Campagnolo brand and the other a Kona brand). After riding for maybe 50 miles or so, the seat tilt seems to have shifted slightly (despite my putting a gorilla move on the post bolt when tightening). Is this common or am I just too fat?

When I use two-bolt seat posts, the seat tilt NEVER shifts, and I can adjust tilt in much finer increments. I understand that the one-bolt models are slightly lighter than the to-bolt models, but this is not a significant issue for me.

I believe my recent run in with seat pain after an hour in the saddle may have been caused by the saddle shifting to a slightly "nose up" position that I hadn't noticed.

In any case, I'm about to switch out both the Campagnolo and Kona one-bolt posts for two-bolt models on my bikes. Hopefully, this will cure my positioning ills.
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Old 09-29-05, 05:42 AM   #2
DanS
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I don't think it's that they don't hold as well, more likely that if the clamp isn't completely in the serations it might move. I prefer the two bolt posts too, for the fine adjustment.
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Old 09-29-05, 11:27 AM   #3
stapfam
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Quote:
Originally Posted by DanS
I don't think it's that they don't hold as well, more likely that if the clamp isn't completely in the serations it might move. I prefer the two bolt posts too, for the fine adjustment.
There are seat posts and there are seat posts. The two bolt adjusting ones will give you finer adjustment, but a good quality single bolt one is just as effective, and do not move.

Over the years I have only had problems with two seat posts. One was the original 2 bolt one supplied on my Kona Explosif 10 years ago, when the nut Stripped. Easily fixed by replacing the nut, but eventually the post had to be replaced as it was a bit on the light side to give many years use. The other was an OM brand on a Marin that just would not hold position from new. A faulty batch from the factory that was replaced under warranty, but as this was exactly the same I bought another manufacturer.

I don't care whether it is 2 bolt or single bolt, providing it works, and I do not spend out a fortune on trick parts either-- Except for the thudbuster, and that is a bit special, both in quality and price. But if you want the best-----$$$$$$$$
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Old 09-29-05, 01:58 PM   #4
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I have had absolutely no trouble with either Easton carbon, DA aluminum, or nitto...all single bolts. I have a nitto double bolt and it is pretty, but works no better than the single bolt nitto. I haven't had any other types, so my experience is limited.
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Old 10-05-05, 10:28 AM   #5
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Speaking of which...on my single bolt Al 27.2mm post on my new Bianchi, one serration difference really changes the attitude of the seat more than I like. I cannot dial in precisely the right seat tilt I prefer. Can someone recommend a good valued Al set-back seat post that one can finely tune the seat tilt?
Thanks,
George
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Old 10-05-05, 12:57 PM   #6
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Hi George!

The last time your question came up in the mechanics' forum (I think) the suggestion was to take a rat-tail file and remove the serrations. After that, you can set anywhere you want.
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Old 10-05-05, 01:18 PM   #7
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Quote:
Originally Posted by biker7
Speaking of which...on my single bolt Al 27.2mm post on my new Bianchi, one serration difference really changes the attitude of the seat more than I like. I cannot dial in precisely the right seat tilt I prefer. Can someone recommend a good valued Al set-back seat post that one can finely tune the seat tilt?
Thanks,
George
try poppin the seat top clamp piece off and reversing. on the serrated ones I have, the serrations are not laid in symetrical, so the angles change depending on which way the top piece faces. You might find a comfortable 'new angle'...
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Old 10-05-05, 01:34 PM   #8
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Quote:
Originally Posted by FarHorizon
Hi George!

The last time your question came up in the mechanics' forum (I think) the suggestion was to take a rat-tail file and remove the serrations. After that, you can set anywhere you want.
Hi FarHorizon,
You know the slippery slope there...remove the serrations and you set yourself up for the angle changing during a long ride...why they are there. Other thing is I run my Brooks back...actually forward on its rails to achieve as much set-back as possible for my long femurs even with stock Bianchi set-back seat post so without serrations there is quite a big moment on the clamping surface...hence reluctant to go there.
My $0.02...may work, just reluctant to try it. Thanks for the advice,
George

Last edited by biker7; 10-05-05 at 01:39 PM.
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Old 10-05-05, 01:38 PM   #9
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Quote:
Originally Posted by cyclezen
try poppin the seat top clamp piece off and reversing. on the serrated ones I have, the serrations are not laid in symetrical, so the angles change depending on which way the top piece faces. You might find a comfortable 'new angle'...
Yup...excellent idea...tried it. Darn thing is symmetric. No joy in reversing it.
We think alike and I tried. May opt for an offset Thompson Elite which has a fine adjustment. The Brooks B.17 I am running on my bike is real sensitive to nose position...or should say more correctly, my bottom is on long rides
George
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