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Seatpost submarining

Old 05-24-24, 11:17 AM
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Seatpost submarining

I put a quick release seat post binder bolt on my Giant OCR3. The first ride on it, I noticed the post had submarined maybe 1-2 mm into the seat post after a few miles. I am afraid to tighten the quick release nut too much because I don't want to crack the frame. My question is: how much should I tighten it to stop the post sinking?
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Old 05-24-24, 11:23 AM
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Since there's no way to use a torque wrench on a QR seatpost clamp that I'm aware of, I'm curious what kind of answers you expect. ("Tighten until the frame cracks, then back off a quarter turn.")
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Old 05-24-24, 11:42 AM
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Maybe try a quarter of a turn tighter at a time until it stops slipping or the frame cracks!
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Old 05-24-24, 11:45 AM
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You also could try some assemble paste on it - the grit may help it not slip.
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Old 05-24-24, 11:47 AM
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When something like your seat post slips, the typical assessment will be that it's too loose. So you have to tighten something. Whether that's your new quick clamp or your old clamp, that will be your choice. Check your quick release and be sure it actually fits properly all around the tube and isn't too big and clamping on it's own limits.

Is this a carbon frame and seat post? Carbon assembly paste might help if you didn't use any or what was on them has come off.
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Old 05-24-24, 11:50 AM
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I would only use assembly “grit” paste if you are not planning to adjust the seatpost height on the fly. In which case I wouldn’t use a QR.
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Old 05-24-24, 12:16 PM
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I'm assuming that the OCR3 is aluminum?

Here's a way to think about it: With a standard seatpost collar, you would tighten it till the post didn't slip at all, and you wouldn't worry about cracking, because it's designed to work with a seatpost collar that tight. For the QR seatpost collar to hold the seatpost without slipping, it has to be as tight as the regular collar. It's not going to be tighter than the standard collar just because it's a QR - they work on the same principle - squeezing the seat tube top into a small enough diameter that it grips the seatpost tightly.

So, clamp it in place. Make some marks on the post, one right at the collar, then another 1 cm up, maybe another higher still. Ride. Check if the first mark disappeared. If it did, raise the post, tighten the QR 1/4 turn, and ride some more. At some point, you'll have reached the point of no slippage. Make a mental note how hard it is to close the QR, and that should do it.

Question, though - why a QR?
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Old 05-24-24, 03:16 PM
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Aluminum doesn't like to be flexed repeatedly. Don't know how much more use you are hoping to get from the bike but it's something to consider.
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Old 05-24-24, 03:44 PM
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Originally Posted by genejockey
I'm assuming that the OCR3 is aluminum?

Here's a way to think about it: With a standard seatpost collar, you would tighten it till the post didn't slip at all, and you wouldn't worry about cracking, because it's designed to work with a seatpost collar that tight. For the QR seatpost collar to hold the seatpost without slipping, it has to be as tight as the regular collar. It's not going to be tighter than the standard collar just because it's a QR - they work on the same principle - squeezing the seat tube top into a small enough diameter that it grips the seatpost tightly.

So, clamp it in place. Make some marks on the post, one right at the collar, then another 1 cm up, maybe another higher still. Ride. Check if the first mark disappeared. If it did, raise the post, tighten the QR 1/4 turn, and ride some more. At some point, you'll have reached the point of no slippage. Make a mental note how hard it is to close the QR, and that should do it.

Question, though - why a QR?
Thank you for the advice. I will follow it. The reason for the QR is that my girlfriend will probably be riding it from time to time over the summer, and I wanted something that was quick and easy to adjust for height.
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Old 05-24-24, 04:38 PM
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Originally Posted by JochenRindt
Thank you for the advice. I will follow it. The reason for the QR is that my girlfriend will probably be riding it from time to time over the summer, and I wanted something that was quick and easy to adjust for height.
You know, the post will be greasy when you raise it again, right?
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Old 05-24-24, 04:55 PM
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Best not mention that to her....
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Old 05-24-24, 05:14 PM
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I have used Clear Thin packing tape right at the quick release site. After a year or two I then just cut out a strip of aluminum from a beer can and used that.
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Old 05-24-24, 06:11 PM
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Carbon paste has a grit to it, can help with slippage. I have also added a bit of fine kitty litter to regular lube.
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Old 05-24-24, 08:08 PM
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I had a seatpost slipping with a quick release. I kept trying to make it tighter and struggled to get the quick release to close. At some point I lubricated the quick release cam, and that fixed it! No more fighting to get the quick release to close, and the post stayed put.
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Old 05-25-24, 05:22 AM
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Originally Posted by nathand
I had a seatpost slipping with a quick release. I kept trying to make it tighter and struggled to get the quick release to close. At some point I lubricated the quick release cam, and that fixed it! No more fighting to get the quick release to close, and the post stayed put.
What exactly do you mean by the cam in the QR?
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Old 05-25-24, 05:39 AM
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Originally Posted by JochenRindt
What exactly do you mean by the cam in the QR?
Basically anywhere in the circled area that moves. Also, is your QR clamp of good quality (like the pictured model)?

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Old 05-25-24, 05:42 AM
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Originally Posted by JochenRindt
What exactly do you mean by the cam in the QR?
Sy's pic's better description than what I'd posted.

(OP, you any relation to Jochen Rindt, F1 race car driver?)

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Old 05-25-24, 10:37 AM
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I wish I were a relation to the 1970 World Driving Champion. I've always loved Formula One and my dad used to have a Lotus, though.
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Old 05-26-24, 10:12 AM
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Submarining?
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Old 05-26-24, 04:23 PM
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Originally Posted by tomato coupe
Submarining?
Push the button, Max!
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Old 05-29-24, 09:41 AM
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You could also put a worm clamp on the seat post so it can't slip further from a clamp that just isn't getting quite tight enough. Then the seat tube clamp won't have to hold all that well. They make collars for seat posts too that are intended for allowing you to drop the saddle to a preset height for others. And they can keep the post from slipping further too. And they look a little better.

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Old 05-29-24, 11:53 AM
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Originally Posted by Iride01
You could also put a worm clamp on the seat post so it can't slip further from a clamp that just isn't getting quite tight enough. Then the seat tube clamp won't have to hold all that well. They make collars for seat posts too that are intended for allowing you to drop the saddle to a preset height for others. And they can keep the post from slipping further too. And they look a little better.
Kinda defeats the purpose of a QR.
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Old 05-29-24, 12:17 PM
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Originally Posted by Kontact
Kinda defeats the purpose of a QR.
Yeah, but not so much if the majority of time the bike is used is when the saddle is at that lower position. And it'll let you know for sure if the saddle is indeed slipping when at the higher position.

Not a perfect solution. But a kludge that might make a quick fix and be tolerable for a time.
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