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Seat-post clamp - am I asking for trouble?

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Seat-post clamp - am I asking for trouble?

Old 06-19-12, 07:54 PM
  #1  
Lexi01
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Seat-post clamp - am I asking for trouble?

So I just bought a 3rd bike to be used solely to ride to the train station and leave locked up all day - so I want to make it tamper proof...

The final thing I need to do is swap the seatpost clamp from quick release to allen key...I reckon that'll be less prone to idiots pulling off your seatpost and walking away!

But its a 34mm (not 34.9) and I can't find one anywhere...

So the question is - I've just pulled off the quick release lever and replaced it with an allen key - it seems to be holding...but is it dangerous? Am I asking for trouble?
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Old 06-19-12, 08:36 PM
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I'd say that if it is holding OK you should be alright. What is the worst that can happen if the clamp fails? Your seat will drop down to the top of the seat tube.

Thieves have the same access to hex keys as well as you do. Once you are sure that the clamp is working OK you can increase the security by securing a ball bearing in the hex key drive with melted wax or something similar which can be removed if needed but will slow down a thief. You can do this to other hex bolts as well.

You can never make a bike tamper proof; a determined crook with time will always defeat any measures you can take. All you can do is to make another bike easier to steal parts from than yours.
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Old 06-19-12, 08:40 PM
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Originally Posted by dsbrantjr View Post
I'd say that if it is holding OK you should be alright. What is the worst that can happen if the clamp fails? Your seat will drop down to the top of the seat tube.

Thieves have the same access to hex keys as well as you do. Once you are sure that the clamp is working OK you can increase the security by securing a ball bearing in the hex key drive with melted wax or something similar which can be removed if needed but will slow down a thief. You can do this to other hex bolts as well. All you need to do is to make another bike easier to steal parts from than yours.
Thanks. I guess its not so much thief proof but protecting against the idiots who see a bike and on a whim decide to take a seat home as a laugh. They're less likely to have a set of allen keys on them.

I like idea of the ball bearing though...never heard that before.

I also reckon that the worst that could happen if the post slides down all the way in a hurry is that I'm likely to come off the bike...I'll be in a suit too...so not something i really want to do on my way to work!

Last edited by Lexi01; 06-19-12 at 08:45 PM.
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Old 06-19-12, 11:57 PM
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Originally Posted by Lexi01 View Post
Thanks. I guess its not so much thief proof but protecting against the idiots who see a bike and on a whim decide to take a seat home as a laugh. They're less likely to have a set of allen keys on them.

I like idea of the ball bearing though...never heard that before.

I also reckon that the worst that could happen if the post slides down all the way in a hurry is that I'm likely to come off the bike...I'll be in a suit too...so not something i really want to do on my way to work!
The q/r clamp is just a bolt with a lever on one end instead of a conventional nut or bolt head. Replace it with another type of bolt is all you're doing. I can't imagine any reason it's any more likely to slip "catastrophically" than the Q/R bolt. Sure, seat posts do slip, but I've only seen it happen gradually unless the thing is assembled/tightened in a totally clueless manner, and that doesn't sound like you. Put a piece of tape around the post and you'll notice right away if it starts slipping and you can tighten it.
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Old 06-20-12, 01:36 AM
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Originally Posted by Lexi01 View Post
I've just pulled off the quick release lever and replaced it with an allen key - it seems to be holding...but is it dangerous? Am I asking for trouble?
I'd be pretty surprised if there's a problem.

But if there's any doubt in your mind, you should post a picture.
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Old 06-20-12, 02:11 AM
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Tube OD are Imperial 1,1/8, 1,3/8 1,25.. metric numbers are equivalents..
Measure !
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Old 06-21-12, 01:17 AM
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Originally Posted by fietsbob View Post
Tube OD are Imperial 1,1/8, 1,3/8 1,25.. metric numbers are equivalents..
Measure !
Sorry mate - what's Tube OD?

Every clamp I'm looking at over here in Oz is metric.
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Old 06-21-12, 04:09 AM
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Originally Posted by Lexi01 View Post
Sorry mate - what's Tube OD?

Every clamp I'm looking at over here in Oz is metric.
Outside Diameter, 1 1/8" is 28.6mm, 1 1/4" is 31.8 and 1 3/8" is 34.9mm (approximately).
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Old 06-21-12, 04:18 AM
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Only thing I'd keep in mind, is that hardware store bolts come in different grades. Personally I try to keep at least grade 8 on anything load bearing...
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Old 06-21-12, 05:59 AM
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Originally Posted by xenologer View Post
Only thing I'd keep in mind, is that hardware store bolts come in different grades. Personally I try to keep at least grade 8 on anything load bearing...
There's no real need for a high strength bolt. Seat binders have used 5mm mile steel and even brass bolts successfully for years. In any event the worst consequence of an under spec.d bolt is that it'll break while being tightened, rather than later while in service. Given that commercial hardware plating is usually inadequate for outdoor use, I'd opt for a stainless bolt, rather than a high strength one.
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