Folding Bikes - 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.


http://i82.photobucket.com/albums/j242/hawkingnovember/DSCN7806.jpg

http://i82.photobucket.com/albums/j242/hawkingnovember/DSCN7805.jpg

http://i82.photobucket.com/albums/j242/hawkingnovember/DSCN7809.jpg

http://i82.photobucket.com/albums/j242/hawkingnovember/DSCN7810.jpg

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.

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.

I hear what you're saying and you're probably right, however it does reach far enough to be fully clamped by the adjustment lever. Admittedly, I would feel much better if the tapered portion were at least an inch longer.

totally off topic, but I would call this the "Giraffe" mod.

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

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 ?

Or does that QR lever grip the reduced end ?

Yes, it works as you see it. No wedge needed if you retain the stock Raleigh QR lever.

The Soma item is another way to go as well.

Look's scary to me.

I'm not 100% trusting of my stem and that goes 3-4" into the steerer.

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.
http://i160.photobucket.com/albums/t188/juried/misc/IMG_0026.jpg?t=1291928215

http://i160.photobucket.com/albums/t188/juried/misc/IMG_0028.jpg?t=1291928317

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.

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 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.

I think Fish Man has the right Idea, 4 inches below the shoulder ..

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.

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.

Yes, that is a good point. I was thinking purely about the stem weakness.

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

stevegor,

got a close-up pic of the finished weld? I'd be eager to check that out.