Who Knows a little about Peugeot PX-10 seat tube construction?
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Who Knows a little about Peugeot PX-10 seat tube construction?
I have to admit it... I never once gave it a thought before, but today I was cleaning a late 60's PX-10 frame and noticed that there was blockage about 8" down the seat tube. I shined a flashlight down the tube and even poked a long rod down there and sure enough it ended.
It's dark down there and there is a slight amount of corrosion, so I can't exactly tell how it is constructed. I am assuming that it is designed to prevent objects or water from getting down there... and not that I have a foreign object stuck in the tube...?
Any one know how the seat tube is designed? Anyone have a diagram? Am I nuts?
Now I am going to have to take all the seat posts off all of my bikes to find out if they are all made this way or if this is unusual. Anyone know so they can save me the trouble???
It's dark down there and there is a slight amount of corrosion, so I can't exactly tell how it is constructed. I am assuming that it is designed to prevent objects or water from getting down there... and not that I have a foreign object stuck in the tube...?
Any one know how the seat tube is designed? Anyone have a diagram? Am I nuts?
Now I am going to have to take all the seat posts off all of my bikes to find out if they are all made this way or if this is unusual. Anyone know so they can save me the trouble???
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Oh, how stupid of me...
Why don't I just check out the OTHER PX-10 I have and see if it has the same stop.
BRB, BF-CV...
Why don't I just check out the OTHER PX-10 I have and see if it has the same stop.
BRB, BF-CV...
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The other bike has the same thing... and I measured this time, 6" down.
So it's not a treasure map or a pounded down seatpost, or even old malted milk balls.
But I still would like to know how it is made...?
So it's not a treasure map or a pounded down seatpost, or even old malted milk balls.
But I still would like to know how it is made...?
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I'm also just making this up, so..... yeah....
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construction and component design.
Chombi
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85(?) Vitus Plus Carbone 7
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That's almost as wierd as the floating wooden plug in my PX10's steer tube. Nobody has ever been able to give me an explanation for that plug that makes sense to me.
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Hey! My PX-10 frame has the seat tube plug as well! Mine is at depth of 6 or 7 inches and you can easily see it with a flashlight. I thunked it gently with a rod, and it thunked back, feeling soft and movable, feeling like cork or balsa wood. I'm guessing it's a block for debris or water, to prevent it flowing down to the BB. Cork makes sense because it could (wine bottle technology, how French!) be shoved down a clean new tube, and would expand when it gets past the butt area. Some softer balsas can have the same characteristic, but it's really not as elastic as cork (my model airplane days many many days ago!).
It would also serve to damp vibrations in the seat tube. This could be part of the perception of a PX-10 frame. Some think such frame tube resonance or ringing is a significant part of percieved ride quality.
It would also serve to damp vibrations in the seat tube. This could be part of the perception of a PX-10 frame. Some think such frame tube resonance or ringing is a significant part of percieved ride quality.
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Remember, butted tubing means it's thicker at the ends and not the middle, so you cannot just drop items down the tube and expect it to stop and jamb against a section in the middle. The thinner wall section at the middle will just let it drop down towards the BB shell or lower butted section, much lower than the few inches down the OP noted on his PX10. My 80's Peugeot PSV does not have this plug in it. I figure that they used to do it back then for some obscure "French" bike building design logic/purpose.........which is not surprising these days when looking back at older French bike frame
construction and component design.
Chombi
84 Peugeot PSV
85(?) Vitus Plus Carbone 7
construction and component design.
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84 Peugeot PSV
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#14
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The plugged steerer tube was to keep the fork from flying off if you cracked the steerer tube. It was more common on Track bikes where stresses are greater, although on mountain decents I would imagine theres a good amount of torque applied to the steerer.
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That's one of the explanations I mentioned that makes no sense. The plug is less than an inch tall and is loose in the tube.
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Thanks for all the conversation. I am surprised that so far no one here has any authoritative information... you guys have such experience.
It's good to know that there are still some mysteries in the world to be solved... however, there are still a couple of Peugeot experts that have yet to find this thread.
I will examine the cork possibility (which I find elegant) later when I can remove the bottom bracket and see if it does the same thing going upwards.
Do you think I should get out my sawzall and open her up for science? I'm sure a cutaway section would put this mystery to bed once and for all!
It's good to know that there are still some mysteries in the world to be solved... however, there are still a couple of Peugeot experts that have yet to find this thread.
I will examine the cork possibility (which I find elegant) later when I can remove the bottom bracket and see if it does the same thing going upwards.
Do you think I should get out my sawzall and open her up for science? I'm sure a cutaway section would put this mystery to bed once and for all!
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I have a India-made Hercules roadster frame who's seat tube was filled at least 4" with gear grease, down by the bottom bracket. Nice debris stopper.
#18
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The last bottom bracket I serviced had seeds, leaves, debris. Lots of it. I tapped on the seat tube for a while and it just kept falling out. Can mice get into a seat tube? The only thing I could think of.
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Seeing that most steer tubes break above the fork crown, the story is pure hoopla, as Dirtdrop says. Someone was having a gag at the expense of Big Chainring, IMO.
-Kurt
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-Kurt
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Wood dowels were often inserted into steer tubes as a safety measure in the event of fork failure. I'm not sure why yours in "floating" but perhaps the wood has dried and shrunk over the years?
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Road Fan,
I think you win the prize. There is indeed a stopper of cork within the seat tube of unknown length. I pulled a shard of loose cork out of my other PX-10 and confirmed this. As well, it is cleaner in that bike and I can clearly see the texture of cork within the tube.
The discussion now becomes: WHY?
Is it merely for protection from debris/moisture getting into the seat tube?
Is there a performance aspect to this?
Does anyone know other manufacturers who used this method?
Quick, everybody check your late 60's era road bikes!!!
I think you win the prize. There is indeed a stopper of cork within the seat tube of unknown length. I pulled a shard of loose cork out of my other PX-10 and confirmed this. As well, it is cleaner in that bike and I can clearly see the texture of cork within the tube.
The discussion now becomes: WHY?
Is it merely for protection from debris/moisture getting into the seat tube?
Is there a performance aspect to this?
Does anyone know other manufacturers who used this method?
Quick, everybody check your late 60's era road bikes!!!
Hey! My PX-10 frame has the seat tube plug as well! Mine is at depth of 6 or 7 inches and you can easily see it with a flashlight. I thunked it gently with a rod, and it thunked back, feeling soft and movable, feeling like cork or balsa wood. I'm guessing it's a block for debris or water, to prevent it flowing down to the BB. Cork makes sense because it could (wine bottle technology, how French!) be shoved down a clean new tube, and would expand when it gets past the butt area. Some softer balsas can have the same characteristic, but it's really not as elastic as cork (my model airplane days many many days ago!).
It would also serve to damp vibrations in the seat tube. This could be part of the perception of a PX-10 frame. Some think such frame tube resonance or ringing is a significant part of percieved ride quality.
It would also serve to damp vibrations in the seat tube. This could be part of the perception of a PX-10 frame. Some think such frame tube resonance or ringing is a significant part of percieved ride quality.
#25
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Road Fan,
I think you win the prize. There is indeed a stopper of cork within the seat tube of unknown length. I pulled a shard of loose cork out of my other PX-10 and confirmed this. As well, it is cleaner in that bike and I can clearly see the texture of cork within the tube.
The discussion now becomes: WHY?
Is it merely for protection from debris/moisture getting into the seat tube?
Is there a performance aspect to this?
Does anyone know other manufacturers who used this method?
Quick, everybody check your late 60's era road bikes!!!
I think you win the prize. There is indeed a stopper of cork within the seat tube of unknown length. I pulled a shard of loose cork out of my other PX-10 and confirmed this. As well, it is cleaner in that bike and I can clearly see the texture of cork within the tube.
The discussion now becomes: WHY?
Is it merely for protection from debris/moisture getting into the seat tube?
Is there a performance aspect to this?
Does anyone know other manufacturers who used this method?
Quick, everybody check your late 60's era road bikes!!!
The main concrete benefit I can think of is to block debris from falling into the greased bearing. I doubt Peugeot used BB sleeves, like Campy and some of the Japanese companies did. The more I think about it the better idea I think it is to seal teh BB bearing area.
If I was their product manager I'd probably have resisted deleting the seat tube cork, even if there was a BB sleeve, if it showed any benefit to ride quality. My frame has some internal rust above teh cork, so it was containing water as well as debris. I really don't get it about the fork tube plug. I wonder if there are corks in the top and down tubes? That would be evidence of a forward-looking product tuning process at Peugeot. It's nearly weightless damping system.
Has anyone here seen the dismantling of a PX-10 frame, or have a mangled one that can be cut up?
Bottom line: No, Ivan, I don't have a really strong theory of why there's cork in there. But if my debris barrier explanation turns out to be true, add a set of wheels to my prize package, ok bud?
BTW, I know my early '70s UO-8 does not have any head or seat tube plugs in it. I just got another similar frame, which has no fork plug, but I haven't taken a good look yet into the seat tube. None of my later (early '80s) Italian frames have this. Same for my '73 Super Course and my 1980 Woodrup. Sorry, no more late '60s stuff in my stable.
Last edited by Road Fan; 12-24-09 at 05:20 PM.