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Yea or Nay? A Weld-Free Bike Frame with "Mortise & Tenon" Joinery
The City Vanture e-bike is user-assembled
Bike nerds, I need to hear from you: Are the welds on bike frames typically a problem?
An upstart manufacturer called Vanpowers Bike thinks so, and designed the frame of their City Vanture e-bike to be weld-free. "Many one piece frames are heated at high temperatures after welding," the company writes. "The frame tends to deform after being heated, and repeated manual correction and grinding will cause the frame to have a center deviation, resulting in an uneven and fragile frame structure that can be strenuous and unbalanced when riding." I'm not an avid cyclist, and had never heard that this was an issue.
"To resolve the problem," they continue, "City Vanture has an assembled frame with a symmetric deviation <1mm, the world's first electric bicycle to use this frame technology, making the riding smoother and better."
They designed the bike with what they refer to as "mortise & tenon"—and occasionally, "tenon & mortise" joinery, neither of which accurately describe their joint, at least from a woodworking perspective. "To make the frame more sturdy, City Vanture uses a tenon-and-mortise structure to ensure the stability of the electric bicycle. Woodworkers around the world have used tenon-and-mortise structures for thousands of years. They furnish a strong outcome and connect by either [sic] locking into place."
What they've in fact developed is kind of a scarf joint, at least axis-wise, whereby tubes are slid inside a connector at the joints. The connector is then bolted fast:
The bike arrives flatpacked, and the user assembles it. Here's the how-to video:
Enter a caption (optional)
Bike people: Does this type of construction confer any actual advantage you can see, or is it a gimmick? Am sincerely curious.
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Comments
No prescribed torque values? No thank you. Just "kinda'" tightening will not cut it. The tubes should be keyed for orientation & to prevent twist (after you didn't torque it down properly). This is a kit.
Hi Alan! We have detailed how much torque is required for each part of the screw in the manual. The screws at each position have corresponding torque requirements to enhance the stability of the frame. Thanks for your concern.
Hi Alan! We have detailed how much torque is required for each part of the screw in the manual. The screws at each position have corresponding torque requirements to enhance the stability of the frame. Thanks for your concern.
Thanks for your response. I am still wondering how a layperson would torque the fasters correctly. Most people will not have a Torque Wrench at the ready. I have seen Single Use Fastening Tools that the handle will break off after reaching a specified value. I have personal experience of bad wrenching: my own. As a kid, I improperly torqued a bike component. Let's just say, I ran home a truly, bloody mess. I was very lucky.
You could swap the top tube, down tube and seat tubes for carbon for some weight savings. Though its moot with an ebike.
Also you'd need to include a torque wrench so users don't ugga dugga and crush the tubes. Heck they might go overboard even with alu tubes.
Hi Derek!
They invented a heavy lugged frame. I am not impressed.
Hi ba ken! City Vanture is not heavy in an equivalent aluminum frame, weighing only 34 lbs (15.5 kg) and can be lifted easily. The minimal center deviation is comparable to that of a road racing bike, and the riding experience is excellent. You can even let go of your hands off the handlebars. Check this video: https://www.youtube.com/watch?v=jNEAl9pE2JQ
Hi ba ken! City Vanture is not heavy in an equivalent aluminum frame, weighing only 34 lbs (15.5 kg) and can be lifted easily. The minimal center deviation is comparable to that of a road racing bike, and the riding experience is excellent. You can even let go of your hands off the handlebars. Check this video: https://www.youtube.com/watch?v=jNEAl9pE2JQ
This seems like a solution looking for a problem. I can't imagine who their targeted audience might be. It is going to be a tough sell for their marketing department.
Hi William! City Vanture is our first assembled city road bike for commuters, we want to bring a smoother and faster riding experience for city commuters. We will continue to work to build the next best electric bike. Thanks for your concern.
Also, the 1mm divination…..in which axis? That is quite important for them to specify IF this were to be understood as a real problem to solve.
The highHeat post welding process they speak about is mainly used for aluminum frames to normalize the stresses in the heatEffected zone where cracks are most likely to begin. In the last few decades, metallurgists have created amazing AL alloys that can be hardened but, we’re talking
Seems like a big opportunity for creaking and clicking, which I can't stand while riding. The justification for avoiding welding seems pretty thin. I have owned many bikes of many materials, and most show no grinding after welding.
Thirdly, the idea that frames are typically out of alignment is false. Any good bike manufacturer makes frames that are aligned to exacting standards.
You are right, mortise and tenon joints are used in wood working though the idea is similar. A lugged joint would be a more appropriate description. Traditional lugs on bicycle frames have tubes brazed into the lug and the lug itself can be a thing of sculptural beauty.
Have they not also designed the most easily-stolen bicycle of all time?
Hi Eric, each screw has a corresponding required torque value, and the frame with the screws in place is hard to steal. We are currently in the research and development of the motor lock and fingerprint lock, we also sell anti-theft accessories on the website: https://vanpowers.bike/collections/accessories
As others have said this seems dubious. Most frames aren't that far out of whack, weldings not too bad.
The horse says "NAAAAAAY"
Holy cow what a bad idea. There's no way the end user should be assembling their own bike *frame*. Yikes.
Hi Chris! Thanks for your attention! We believe assembling brings fun and a more balanced and safer riding experience. :)
Solving a problem that really isn't a problem.
Hi Anders, people tend to overlook the symmetrical deviation problem of the frame. As a result, the unstable frame affects the riding experience and riding safety. City Vanture's superior riding experience of the assembled frame can be known by riding it. Thanks for your concern :)
Shoot no way to edit I meant: (they couldn't weld or glue aluminum in those days.)
First of all, there have been other bikes that are assembled this way. Even in the late 1800's there were Aluminum bikes made from cast parts that were bolted together in various clever ways. (thnum in those days). Secondly, I'd find this concept more credible if there were clear pictures of the actual bikes--not 3D models or photoshopped images.
Does it come with a quart of LocTite?
Hi Steve! City Vanture frame has special high-strengtj screws and lock nuts. The screws are made of carbon steel with a strength of 12.9 and are 2 mm longer than those on the market. Other parts are made of 8.8 stainless steel bolts. The screws at each position have corresponding torque value requirements to enhance the stability of the frame. City Vanture's manual will specify how much torque is required for each screw.
Got to say, anything that adds extra component weight is a no from me in this industry. I get the concept, and can kind of see the potential, but the reality of this is it will just never keep up with the alternative even in terms of practicality.
Hi Joshua! Thanks for your attention. The assembled frame is the first step in our research on electric bicycles. We will continue to update the technology to create the next best bicycle. Vanpowers Bike is always working hard to develop bikes with excellent riding experience and safety.
The only advantage that I can see is for international touring cyclists. The break down function would make traveling on planes, trains and busses easier.
Hi Jim, thanks for your concern. But we do not recommend frequently disassembling the City Vanture. The assembled frame has minimal symmetry deviation and brings a very balanced and smooth riding experience. You can even let your hands off the handlebars when riding, which greatly improves safety.