Dropper post collar...
 

[Closed] Dropper post collar - double or single bolt?

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Hi,

Trying to make a bit of a gnarification of my hardtail. Got suspension forks kicking around and thought dropper will be good call.

However a bit of a worry is a fact, that my standard seatpost require quite a bit of force on the clamp to prevent it slipping down.

Not too good for droppers I'm afraid.

Will be using friction paste but also seen these funky double bolt clamps: https://www.tredz.co.uk/.XLC-Seat-Clamp-For-DH-Freeride-PC-B04-_126897.htm

Anyone using anything like that? Any good or just waste of time?

Cheers!
I.

 
Posted : 29/09/2020 8:48 am
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It might not be an issue if it's due to your existing post being undersize.

However, it if is a problem, I might be tempted to try something like that.

 
Posted : 29/09/2020 8:59 am
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Post is correct size, only concession I might think about is using 35.0 collar instead of "standard" 34.9. But I do not believe Salsa Flip Lock comes in 34.9 variety...

Cheers!
I.

 
Posted : 29/09/2020 9:04 am
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I was meaning that the post might be on the lower end of the tolerance rather than you were using the wrong size.

Pretty sure 34.9 Vs 35 is a rounding issue rather than an actual spec issue.

1⅜" is 34.925mm. some round up, some round down.

 
Posted : 29/09/2020 9:06 am
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Christ, if one bolt won't stop it slipping, there's something really wrong.

Lightly sand and degrease the post below the point where it inserts into the frame so it's not slippery. Degrease the inside of the seat tube for an inch or so below the seat clamp. Use a normal seat clamp.

 
Posted : 29/09/2020 9:08 am
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The frame's seat tube bore might be a touch oversized, that happens sometimes. If you have the required tool, I'd check that first.

Anyway, if the clamp is really that tight, most dropper posts will tell you that by getting sticky at some point of the travel.
If, when subjected to the needed tight clamp, the dropper cycles more or less normally, I wouldn't bother too much. Specially if the dropper isn't something fancy

 
Posted : 29/09/2020 9:10 am
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I was meaning that the post might be on the lower end of the tolerance

Ahhh... Gotcha...

The frame’s seat tube bore might be a touch oversized

Thanks! Obvious one I need to check.

Dropper definitely won't be fancy, however in the current state of supply anything, even on the budget feels like top shelf commodity xD

Cheers!
I.

 
Posted : 29/09/2020 9:57 am
 5lab
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i've used a double bolt collar on a 27.2 dropper post as the normal collar clamped it too hard - the walls on the lower part of thin dropper posts is really thin and easy to pinch, so spreading the pinch load helped it significantly

for your problem - you're tightening the clamp up a lot, but if the tube is slgihtly oversized not much of that force is being applied to the post (which is why its slipping) - so I think a dropper would be no different. I'd try it with your current clamp, if that doesn't work upgrade to a dual bolt at that point

 
Posted : 29/09/2020 10:36 am
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Thanks!

I'll buy it anyways. Looks like not massive investment, even if it proves to be a bit meh...

Will check all the measurements and if need to be might put beer can shim to make post fit better.

Cheers!
I.

 
Posted : 29/09/2020 11:12 am
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If you go down the coke can shim route and it works give me a shout and I'll send you some stainless steel shim in the same thickness as a coke can.
It'll last a whole lot longer.

 
Posted : 29/09/2020 11:27 am
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I suffer from the same problem, my fix was to measure the max drop I could get away with for a dropper post, and then cut a length of tube that sits on top of the seat post clamp and buts up to the collar of the dropper.
It's a Ti frame so I cut the spacer from stainless steel so it almost matches the frame perfectly, so now it just looks like a slight extension of the seat tube.
150mm dropper and about a 40mm spacer.
No pictures sorry but if you're curious I can tag some on tomorrow.

 
Posted : 29/09/2020 11:36 am
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You could try one of these?
https://www.bike24.com/p2122564.html

 
Posted : 29/09/2020 12:21 pm
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Ermmm... And how do you install that last one?

singlespeedstu might get back to you mate.

monkeyfiend if you can post some pictures will appreciate.

Cheers!
I.

 
Posted : 29/09/2020 3:37 pm
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collar 1
collar 2

 
Posted : 05/10/2020 10:26 am
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Ermmm… And how do you install that last one?

The lip on the bottom of the collar goes under the top lip on your seat clamp so the internal O rings grip your seatpost above the clamp as well as your frame gripping the post below.

 
Posted : 05/10/2020 12:21 pm