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Old 04-17-11, 08:29 PM   #1
rnt654
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Peugeot Quill Seat post

So I recently bought a Peugeot frame for $30 I didn't realized that it didn't have a seat post clamp. I bought it at a bike swap meet and the person I bought it from knew what he had and failed to mention anything. So I feel I got burned but it was my fault buyer beware I guess. If he did mention something I probably wouldn't have bought it. I didn't know they made bike frames without seat post clamps. I didn't know that quill seat post or expanding seat post even existed.

So after talking with a couple of people and looking online I made my own Quill stem seat post. Here is my question. What success has anyone had with their DIY quill seat post or expanding seat post? Did it actually work for you? I haven't had a chance to ride my bike yet with the homemade quill seat post. I'm just hoping someone out there has been successful with their Quill seat post or expanding seat post. Any advice on making a quill seat post. What has worked and what hasn't.

Thanks
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Old 04-18-11, 12:29 AM   #2
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I've never heard of this. Picture of the seat tube by the clamping area? Can't you just buy a standard clamp and put it around the seat tube?
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Old 04-18-11, 01:46 AM   #3
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this is what the frame looks like


Last edited by rnt654; 04-18-11 at 01:53 AM.
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Old 04-18-11, 01:58 AM   #4
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This is what you have to build to get it the seat to work. The one I build looks very homemade. This is one that was for sale for about a couple of hundred dollars.

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Old 04-18-11, 05:37 AM   #5
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I'd be real careful there. Unless the seat tube has some sort of reinforcement where your diy quill will sit, you could easily damage the seat tube.
You might want to consider building a quill seatpost with an slit tube around it to distribute the expansion load from the quill.
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Old 04-18-11, 09:53 AM   #6
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a plain type seat post of appropriate diameter, is a better start,
than a Super Record.

then perhaps you can cut the base of it, to expand, and a long straight bolt,
to pull up, against a flat washer across the 7/8'' part at the top of the post..
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Old 04-18-11, 11:27 AM   #7
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looks like something pretty simple to make with a mill, lathe and set of collets. Sourcing the materials would be biggest barrier to making one. As fietsbob pointed out a seat post in the correct diameter would be a good start. If you are really interested in making a quill or expanding seat post send me a PM and maybe we can work something out.
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Old 04-18-11, 07:30 PM   #8
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I'm interested in making a expanding seat post. what would be better cause I've seen a couple online like this one http://www.flickr.com/photos/kirkohly/5325360365/ It doesn't need to be as fancy it could be a seat post without a build in clamp. If you have some pictures and some directions in would really appreciate it.
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Old 04-18-11, 10:19 PM   #9
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some of those French frames use a novel small diameter . like 23mm
or perhaps somewhat more common 25.0

what machine shop access do you have.. ? have access to an inside micrometer?

Plain posts from QBP http://www.bikeman.com/ST2021.html
I think 25.0 is also made, by Kalloy, though 1" is as small as stocked by this retailer.

the above post is a previous American Classic, discontinued..
there is a continuous ID with a rubber plug at the top but it is not round ,
the wall is thicker fore and aft, to stiffen, so that needs to be re machined as well.

Last edited by fietsbob; 04-19-11 at 10:10 AM.
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Old 04-19-11, 05:53 AM   #10
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I'm interested in making a expanding seat post. what would be better cause I've seen a couple online like this one http://www.flickr.com/photos/kirkohly/5325360365/ It doesn't need to be as fancy it could be a seat post without a build in clamp. If you have some pictures and some directions in would really appreciate it.
my gut instinct is to say the sliding type quill that you linked to in a previous post would be better, but that is an unqualified statement with no evidence to back it up. Of course, the expanding type will be easier to fabricate. I have no pictures as I have never built one. If you have any experience running a metal lathe I can write up a procedure that will make you an expander plug. Then again, if you had access to a lathe this whole thing would be trivial because the part is so simple.

If you have a correctly sized seat post already, and a set of calipers, you can head to a local machine shop and have them make a tapered plug. This may cost much more than you spent on the frame so be warned. I may be headed into the university machine shop in the next few weeks to make some parts for a project at work. If you can get me the inner diameter and outer diameter of a properly sized seat post I will see if I can dig up some scrap stock and make the part when I get there.
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Old 04-20-11, 09:27 PM   #11
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some of those French frames use a novel small diameter . like 23mm
or perhaps somewhat more common 25.0

what machine shop access do you have.. ? have access to an inside micrometer?
Looks like the seat post diameter is 26.4 which seems like a odd size. I've been checking around my town for one but looks I would have to order on online. I don't really have access to a machine shop but I have a friend who can help me make the cut. I just hope it works.
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Old 04-20-11, 09:31 PM   #12
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my gut instinct is to say the sliding type quill that you linked to in a previous post would be better, but that is an unqualified statement with no evidence to back it up. Of course, the expanding type will be easier to fabricate. I have no pictures as I have never built one. If you have any experience running a metal lathe I can write up a procedure that will make you an expander plug. Then again, if you had access to a lathe this whole thing would be trivial because the part is so simple.
I think it would be better too. I've never made anything like this or have had this kind of problem with a bike build. It just seem very rare to have a bike without a seat post clamp built in. As soon as I get all the part and finish the build I'll take a few pictures of it.
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Old 04-21-11, 12:49 AM   #13
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Plain Kalloy will have a 26.4 to work with.
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Old 04-21-11, 01:30 AM   #14
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The idea of an expander holding a seatpost on has been around in BMX/freestyle for a while. The ones I've seen use one bolt to hold the pivotal seat onto the post, which also threads into the expander and pulls it up into the post, which has a pair of slits like a stem. The posts used are typically around an inch long, and seem to be referred to as "nub posts". As such, it's clearly possible for a such a design to work, althoug BMXers don't really sit on their saddles, and the post is too short to exert much leverage, so the fitting doesn't have to resist as much force as it would on a road bike. You'd certainly want a lot more post inside the frame, to start with.
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Old 04-21-11, 06:13 AM   #15
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Originally Posted by rnt654 View Post
this is what the frame looks like

thats actually my bike in the picture and you can see the original thread here cos i had the exact same problem

http://www.bikeforums.net/showthread...n!!?highlight=

i finally made my own but i probably wouldn't recommend it, i was never too happy with it even though it did work persay. it looked brutal and i didn't have much faith in it. i did what fietsbob recommended and bought a couple of 26.4mm seat posts off ebay making sure there was enough room on the top to drill into the middle of it. i cut the stem exactly like the previous one, a picture of which is in the original post and then used a tapered wooden cylinder off a broom handle as the wedge i looked high and low for one of these and emailled companies in france etc but to no avail. obviously a machined wedge made from aluminium would be better than wood but i didn't have any the wedge from the previous seat post didn't fit because the inside diameters were different. if i can find a picture of it i'll post it enjoy!
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Old 04-25-11, 04:34 PM   #16
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thats actually my bike in the picture and you can see the original thread here cos i had the exact same problem

http://www.bikeforums.net/showthread...n!!?highlight=

i finally made my own but i probably wouldn't recommend it, i was never too happy with it even though it did work persay. it looked brutal and i didn't have much faith in it. i did what fietsbob recommended and bought a couple of 26.4mm seat posts off ebay making sure there was enough room on the top to drill into the middle of it. i cut the stem exactly like the previous one, a picture of which is in the original post and then used a tapered wooden cylinder off a broom handle as the wedge i looked high and low for one of these and emailled companies in france etc but to no avail. obviously a machined wedge made from aluminium would be better than wood but i didn't have any the wedge from the previous seat post didn't fit because the inside diameters were different. if i can find a picture of it i'll post it enjoy!
I've tried to build the seat post a couple of different way and I agree it didn't work out so well. Plus I put about a 200 pound on the seat itself so it didn't feel right and I didn't feel comfortable riding long distance. I may have to scrap this build and find another frame to work with. I didn't think it would be worth the effort looking for and building another seat post of this type.
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