The wedge style clamp is how people usually make these integrated clamps:
I have seen a few examples used in framebuilding. I will try to find some.
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In this video at around the 15-minute mark (Quill Stems! // Paul Brodie's Shop - YouTube) Paul Brodie talks about the need to ovalize the extension tube where it meets the quill to allow for enough filler metal to prevent cracking (aka his ā1/8-inch rule of thumbā. I havenāt heard this mentioned anywhere else. Aside from stems, I can think of several frames Iāve seen where the HT and DT were of similar diameter, violating this rule of thumb. Wondering what you experienced folks have seen/feel about this?
Thanks!
-Jim G
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Janosch, this type can work. Hereās one I made in '85. Threadless steerers hadnāt been invented yet, so this one clamps to a 7/8" tube thatās silvered into the top of a threaded steerer.
Iām a big guy and I raced it for a few years in Norba, briefly a pro (kind of a joke back then) but anyway I think itās strong enough.
This was a long, high-rise stem to use road drop bars for MTB racing. Stems on Norba bikes in the '80s were looong. Lotta leverage on that joint.
I think the key is the binder needs to be strongly attached to the clamp tube. Your idea of attaching it to the extension tube is where you went wrong. Also I donāt see how you can silver braze and then brass braze after, doesnāt that melt out the silver? Maybe I didnāt understand what you meant. Mine is all brass brazed. (Yes I know some people call it bronze, donāt bother educating me, I am stuck in my ways!)
Mark B
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Since today itās working very well. The flex is okay i think you will have the same on an Tune stem ore something
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Love it!
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Thatās awesome. Iāve been considering making something similar. What are the specs of the vertical extension tube?
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Itās 1 1/4 4130chromoly. I used some random heavy wall tubing that was laying in the scrap pile and bored the I.D. out on the manual lathe here at the shop. But if you were to get .065" wall tubing you would only need to skim out ~.006" from the I.D. with a lathe or reamer to slip fit over 1 1/8 steerer. Mine is about 5 1/4" long. I could have easily gone shorter by a couple inches, but I wanted it to cover more of my steerer and leave only one spacer at the bottom to make it look cleaner.
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Thanks Dave! I was considering 1 1/4 x .065, but would feel better with something a little thicker. Mine will be tall like yours too. Might ask someone with a lathe to help me out.
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Right on! If it makes you feel better, Iām 245lbs and have this on a rigid mountain bike turned commuter. Iāve ridden this stem over a month now, and a few of those rides were extremely jarring, bumpy gravel fire road/cow trail rides. At this point Iām extremely confident in this wall thickness.
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Has anyone here ever modified an existing stem? I am in the process of doing a bit of a revamp of a '95 Kona, and I love the original Kona Velocity stem; but it is so long (125mm) and finding a zero rise 80-90mm stem with a more modern 31.8 clamp is providing to be challenging (Nitto has some but they are out of stock everywhere). I was considering to find someone who could TIG a PMW stem plate on for a 31.8 clamp, and then I would repaint it to match the original project 2 fork. I figure a removable faceplate will expand the selection of bars I can run.
I donāt trust my brazing skills for a stem just yet.
Also I donāt know if this is a small project anyone would take on here?
Absolutely love the look of steel stems. Very much would rock one on my FS bike IF it turns out rideable 
. I Think 99% of the modern stems look hideous.
How did you paint it? Just clear coat with some added tint?
Iāve done that quite often, I save steel quill stem just for that. I havenāt did that with the PMW faceplate but that should look good.
Iād love to help but Iām in France, someone located closer might a be a cheaper option 
And if you have a brazing setup, Iād Say do some practice joint and go for it, half the job is already done
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Thanks! I am thinking of it. Will require a bit more practice before I would attempt this. Good to know that folks have thine this before! I contemplated trying to match the original clamp style with the pinch bolts (it looks so nice) but I think the PMW will be way more practical if I wanted to run something with a sharp bend or double decker riser bar. And a lot of the lighter alloy bars seem to be 31.8 with a lot of the 25.4 ones being steel.
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Any framebuilder or fabricator who TIGs should be able to shorten that. Itās not a difficult job.
I think the PMW has a 1-1/4" recess on the back plate that fits the extension tube so check that before you order. For fillet brazed, it would be easy to fill that in if the extension tube is too small but for TIG, I donāt know.
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I just thought TIG because it would be faster and the other parts of the stem are TIG. I was actually going to ask about that diameter of that indentation. Diameter if the tube on the stem is 1.125 so maybe fillet braze is the way to go.
Is that pocket that fits the tube machined flat so that you donāt need to miter the end of the tube? Hard to tell from the photo as I havenāt seen them IRL.
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The circular recess on the paragon stem plate fits a 1.125 tube. What size tube does the stem you want to modify have?
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