I would just like to clarify, that is not my method. I was doing a "pic assist" for the op. It was his first thought on the subject and I advised against it.

I figgure if I split the difference between the existing steering tube and the extender with the stem mounting bolts it should be as safe as it will get. Both bolts will have something to clamp to. I figgure a 3mm headset spacer below the stem, then the stem, then put two 3mm and a 10mm headset spacers on top of the stem should leave a 3mm space for the top cap to set the headset tention. My available length of steerer tube is 21mm and the extender is 30mm for a total of 51mm. The total stackup of spacers and stem will be 54mm. So from the dust cap to halfway of the stem will be 20.5mm.

My only concern will be getting the expander tight enough. I think some removable loktite might be a good idea. Might scuff up the conical washer on the bottom end for better grip. Not sure if the conical washer will want to spin. Spec says "All accessories are made of 7075 aluminum alloy, which is lighter and stronger than 6061. 7075 is the lightest and strongest aluminum alloy".

https://www.ebay.com/itm/154650501497 I'd like to use this but I don't have enough steerer tube for both bolts to compress on. What was your steerer tube length and does both boths compress on it or is it just the bottom bolt? With the shape of it maybe the bottom bolt is enough?

Like I said I just use it to ride around a sporting clay course on a flat gravel path. No hills, no jumps, no 18 yead old mountain trail crazy gettin air stuf. I'm 66 years old, thats how I ride lol.

If all else fails I may have to do the okie quill extender thing.

Thanks for the assist and the advice, I appreciated it. :)

I brought my too short fork to a metal fabrication shop that mostly deals in pipe works.

For their minimum shop price of $120 they put an inner sleeve in the steerer and welded a piece of a donor steerer on. It worked well.

I think it added something like 80gm to the fork.

Otherwise, those extensions should work. If you do, use a real bolt, not a Philips head. You’ll want some locktite on the threads. I might even put green locktite on the mating surface. Remember, this thing is basically keeping you alive and will almost be unserviceable once installed.

Hard to tell for sure from the pics BUT would it be at all possible to remove the headset bearings and “shave off” a total of 6mm from the top and/or bottom of the headtube? With a “standard” headtube, it wouldn’t be much of a job but that rectangular frame tube could be an issue.

Can't shorten the frame any. This is not my bike's photos but this is the orig steerer tube and the orig handlebar stem. It almost looks like the orig top bolt would be above the steerer tube. The tube looks a tad longer then mine. I'll have to measure my orig stem to be sure.

https://cimg7.ibsrv.net/gimg/bikefor...0e1b8002bc.jpg

https://cimg9.ibsrv.net/gimg/bikefor...a436cdacda.jpg

I've used quill to threadless stem adapters, but not setup as hidden, on a couple of bikes. The adapter/extender was aluminum, but the wedge and the bolt were steel.

They function the same as an aluminum quill stem but with a upper section that will accept a threadless stem. I can't imagine anyone selling an adapter/extender where all the components were aluminum.

John

I hope the 7075 will make the difference.

7075 is notable for its high strength-to-weight ratio and improved strength over 6061. Because of this, 7075 is largely used in aerospace, marine and transportation industries. Any industry where high strength and light weight properties are critical, this alloy is preferred. High-end bicycle components, molds for the plastics and tool industries, airframes, and even military-grade rifle receivers all heavily utilize 7075.

https://cimg2.ibsrv.net/gimg/bikefor...08d697a510.jpg

What happened to the hidden stem extender in the video?

John

Those pics were screen shots taken from a youtube video on how to install the handlebars on an engwe 750 pro. This is not me in the video lol.
There is a video on the how to install the hidden extender on this page...
Amazon.com : NIUAWASA Bike Hidden Stem Riser Bike Fork Stem Extender Bicycle Handlebar Raiser Adapter Head Up Adapter Aluminium Alloy Suitable for Road Bike MTB BMX Fixie : Sports & Outdoors

I just measured the orig engwe stem, the upper stem bolt center line "is" in line with the top of the steerer tube, just like my drawing at 21mm. The internal part that surounds the steerer tube and you place the top cap on is 24mm tall. So that results in a 3mm extention for head stack tensioning. Go figure lol.

I am at a loss for words.

John

Ok, I think this is gonna be it. Got the extender today and decided I'm gonna cannibalize it.
Thanks for all the advice and comments, I appreciate it :)
https://cimg0.ibsrv.net/gimg/bikefor...5fe0a81d13.jpg

Ok, I'm not liking this design any more. You want a setup that will be strong and rigid. Strength and rigidity are based upon mechanical design and material of construction. This design essentially has what amounts to a spherical bearing (yes, its a cone and cup, but the cone length is very small compared to diameter). This means that the bolt itself is what resists most of of the bending force. The weakness is that the bolt has a significantly smaller diameter than the tube. Furthermore, this is likely a part made in a country with a wide range of quality control and ethical commitment to safe design. If this was 1950s USA and you be certain you were getting a super high quality (e.g. AN) bolt, and you carefully torqued the bolt properly, perhaps you could have some semblance of trust that this setup would not fail catastrophically. As in the bolt not snapping or stretching so much you lose purchase on the steer tube. But bolts come from heavens knows where these days. Some are great. Some have the stiffness of manchego cheese, the ductility of porcelain, and the stiffness of a pool noodle. The point is, it's the bolt's strengh and stiffness that dominates the failure mode. Six vs seven thousand series has pretty much nil effect on the overall joint strength and performance.

My original conception of your design was that your stem was going to go onto the actual steerer, and that the extender would only provide a little bit of length, just enough to provide some bending stiffness while preventing the stem clamp from "closing on air". But you've added a stem extender (AND high rise bars!), which will increase manyfold the bending moment on that poor bolt! The design creates essentiallly a stress riser, and the extender and high bars amplify the forces that riding will apply to that bolt.

The failure modes are not attractive. Snapping of the bolt means that the bars are connected to the bike by brake cables. Another failure mode is that if the bold stretches the joint loosens and the top part has no torsional communication with the bottom. You'd have handlebars, but they wouldn't steer anything!

The video created by the Chinese(?) fella had the best idea. I liked that video. If it were me (engineer who grew up working in a machine shop and then worked on and off for seven years in a bike shop) I'd get a tube extender that has a solid design (no joints) and that has a swaged smaller diameter section that inserts into your steerer tube, like in the video. That smooth transition from smaller to larger diameter is probably better than a machined design with a sharp shoulder. I'd buy a couple different ones and choose the one with minimal clearance/ightest fit. I'd actually use epoxy to glue the extender into the steerer, and would also tighten the wedge that came with the design (with the clever idea of using an oversize nut for the stop - see the video and dry fit before using epoxy). This is a permanent mod. Once set, sand off any glue that is proud of the setup and woiuld install the stem directly on the extension, not on an extension of the extension.

As a further precaution (I'm a big guy) I'd actually add an external brace. They sell tube clamps for automotive roll bars (pic below). There's pretty ugly and I don't see 1-1/8 inch offerings. Then I was looking for a bike specific product of a 1-1/8 inch clamp made of alloy and couldn't find it. So what I would do is buy a cheap stem of promising design off ebay and would saw it and file it to just leave a 1-1/8 clamp of, say 1.5 inches length. I'd clamp that over the joint between your steerer and extender. In fact, I see an advantage of this functionally: You could adjust the reinforcing clamp for preload, tighten the lower clamp, and then your handlebar stem adjustment and centering could be done without worrying about messing up the preload.

But the critical thing is that I would not ride a design that did not have the tube extender inserted into the steerer, with the stem clamped to the extender. The design shown above has a flaw in that it has all bending moment on the bolt. And 7075 won't help that problem.

https://cimg7.ibsrv.net/gimg/bikefor...807451b12d.png

NO! If you are interested in bikes get active in active threads otherwise google is more your speed. Making non-sense posts to get you to ten posts is silly and doesn't move the forum along.

I would not modify that bike and just leave it alone or find a quality bike that fits better. The quality on some of those folding e-mopeds is poor at best and getting hurt is not a fun way to go.

Here's my ebike with the orig bars at 15 inches high. The lowest setting.
https://cimg8.ibsrv.net/gimg/bikefor...a6ff54b8a5.jpg

Here's my ebike now with the bars at 9.5 inches high.
https://cimg3.ibsrv.net/gimg/bikefor...7080fb3cab.jpg



Here's my setup with the final version as shown in the drawing below.
https://cimg9.ibsrv.net/gimg/bikefor...3f0e61bbe0.jpg

I fixed the drawing to show the handle bar clamp horizontal like the real clamp. My bad :50:
https://cimg8.ibsrv.net/gimg/bikefor...c7d9f00ec5.jpg

Now I'm tryin to add some highway pegs. This setup is not too bad but a little flimsy. I have some foldup pegs commin so the coupling nuts for foot pegs are just temporary. I used a couple of din rails but they are a little thin. I'm tryin to find some thicker ones or something like them.
https://cimg9.ibsrv.net/gimg/bikefor...e2067e6ddd.jpg

Final version of the footpegs :)
https://cimg3.ibsrv.net/gimg/bikefor...8c085371d1.jpg

I would think that adding those pegs probably removes this from being a bicycle in most people’s minds, even an e-bike.

John

Heck, if you were going to add pegs, you could have more easily just rotated your non-drive side pedal 180 degrees so that the 2 pedals were at the same position and left your feet on them all the time because it's clear you're not going to be pedaling this. Would have been faster/cheaper/easier/lighter.

Being 66 years old, I wanted footpegs for the convience and comfort when going from station to station on a sporting clay course. I wanted to leave the pedals as orig just incase something fails and I need to pedal it back to the car. As far as what someone thinks whether this is still a bicycle or even an ebike doesn't really matter. I use it for transportation on a 1.2 mile long sporting clay course. A hundred years ago it would have been called a horse :)

As long as you can keep up with everyone else on the Mad Max set ...

Given the somewhat tenuous attachment of the stem to the steerer, I was initially worried about this being ridden more vigorously, so this is reassuring.

Been thinkin bout adding some flames or machine gun turrets or even a side car. Well maybe next week. Speak softly but ride an intimidating ebike I always say.

It's hell gettin old, it ain't for sissies.:50: