Flipped Seatpost as a Tall Stem (R20)
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Flipped Seatpost as a Tall Stem (R20)
I stole this idea from "ridetoglide" on the Raleigh Twenty Forum. You flip a stock seatpost and stick it in the stock steerer, then use the stock stem tightener to cinch it down. It feels pretty damn secure and the extended height is great. You can either use a clamp-on stem for threadless systems or jam a regular threaded stem in the seatpost and tighten it up real good (i just tried that for mock-up and can't recommend it although it might be fine to do). I have no idea how this will hold up long term, but I plan to only use this bike on slow rides down the MUP. I posted pics of two different stems I had laying around.
DISCLAIMER!: I have not ridden the bike with this set up yet. I don't know if it's safe. It is just an idea. Please don't hurt yourself. Stay in school.
DISCLAIMER!: I have not ridden the bike with this set up yet. I don't know if it's safe. It is just an idea. Please don't hurt yourself. Stay in school.
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IMO, not a good idea, as the tapered down part of the seatpost isn't very long. Does it at least go past the threaded portion?
The minimum insertion for quill stems are about 2" and that seatpost doesn't have that.
so basically, while the idea is interesting, it needs a minor tweaking before it's safe.
The minimum insertion for quill stems are about 2" and that seatpost doesn't have that.
so basically, while the idea is interesting, it needs a minor tweaking before it's safe.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
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IMO, not a good idea, as the tapered down part of the seatpost isn't very long. Does it at least go past the threaded portion?
The minimum insertion for quill stems are about 2" and that seatpost doesn't have that.
so basically, while the idea is interesting, it needs a minor tweaking before it's safe.
The minimum insertion for quill stems are about 2" and that seatpost doesn't have that.
so basically, while the idea is interesting, it needs a minor tweaking before it's safe.
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totally off topic, but I would call this the "Giraffe" mod.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
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My R20 uses this method, however, we did weld on an extra length of tubing.... just to be sure.
Many miles later..... no problems at all
Many miles later..... no problems at all
#6
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Yea, adding length to the 7/8'' end of the seatpost seems a very good idea,
to put the safety line well below the upper headset race ,
and the threads cut into the steerer tube..
SOMA has a long Threadless to threaded conversion quill,
but I don't think it's that long..
Welding on a Quill wedge mechanism, as part of your internal extension,
would be needed to hold it inside the fork, would it not? .
Or does that QR lever grip the reduced end ?
to put the safety line well below the upper headset race ,
and the threads cut into the steerer tube..
SOMA has a long Threadless to threaded conversion quill,
but I don't think it's that long..
Welding on a Quill wedge mechanism, as part of your internal extension,
would be needed to hold it inside the fork, would it not? .
Or does that QR lever grip the reduced end ?
Last edited by fietsbob; 12-09-10 at 01:29 PM.
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I may be the culprit... I remember suggesting this as a possible solution to the R20 stem problem some years ago. I actually did it on a folding bike I refurbished, which was sold like that.
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jur, that's a slick little setup. Has the new owner reported any problems? Looking at the pics again, the new stem is an obvious place for water bottle cage placement. I plan on just running a coaster brake rear wheel and keep the front brakeless (I know, the "safety" continues...) to have the stem be "separable" with no cables of any sort on the bike for when I pack it in the car.
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It's been more than a year ago... I did not get a comeback. It was on ebay so I don't know the new owner. I also just deleted all the pics I had of that bike as sold, I just had these ones left over.
I was a little concerned about the short insertion length, but I reasoned that the tightening bolt provided additional security if it wanted to break off - the bolt would remain attached and tightened inside the steerer.
I was a little concerned about the short insertion length, but I reasoned that the tightening bolt provided additional security if it wanted to break off - the bolt would remain attached and tightened inside the steerer.
#12
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I think Fish Man has the right Idea, 4 inches below the shoulder ..
Though, if the wedge were, itself, adding 3 inches, or so, length.
It would add some support down inside the steerer tube.
Though, if the wedge were, itself, adding 3 inches, or so, length.
It would add some support down inside the steerer tube.
Last edited by fietsbob; 12-10-10 at 11:14 AM.
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Insertion depth by itself does not make it stronger. In a steel steerer, if the quill expander is tightened securely the depth is almost irrelevant beyond a few inches. Whether it is inserted 1" or 4" it is experiencing the same leverage at the point where it exits the steerer, and that's where it would break.
#14
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Given: threads cut for the headset are the weak point on a threaded steerer,
spanning that with the stem quill below that, is a safety margin, benefit.
spanning that with the stem quill below that, is a safety margin, benefit.
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