Bicycles

Assemble-it-yourself ebike forgoes welds for mortise and tenon joints

Assemble-it-yourself ebike forgoes welds for mortise and tenon joints
The City Vanture ebike is presently on Indiegogo
The City Vanture ebike is presently on Indiegogo
View 4 Images
The City Vanture ebike is presently on Indiegogo
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The City Vanture ebike is presently on Indiegogo
The City Vanture is being offered in 11 frame colors
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The City Vanture is being offered in 11 frame colors
A Walk Assistance mode provides a boost as the bike is pushed along
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A Walk Assistance mode provides a boost as the bike is pushed along
City Vanture riders can choose between five levels of motor assistance
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City Vanture riders can choose between five levels of motor assistance
View gallery - 4 images

While aluminum is a very popular choice for bicycle frames, the welds which join the tubes together leave a lot to be desired. Vanpowers Bike's City Vanture ebike takes a different approach, by having the buyer join the tubes via mortise and tenon joints.

First of all, what's wrong with aluminum welds? For one thing, the weld points are usually a weak point in the frame, as they're typically not as strong as the unwelded aluminum alloy to either side. Additionally, many people simply find the big, obvious welds to be visually unappealing.

By contrast, mortise and tenon joints are known for being strong, stable and nice-looking. In a nutshell, they consist of a tenon "tongue" extending from the end of one piece of material, which snugly slides all the way into a mortise hole in the other piece.

In the case of the City Vanture, the frame's 6061 aluminum top tube, down tube, seat tube, seat stays and chain stays all have tenons at either end (basically just smaller-diameter sections of tubing). These slide into round mortises at the frame's junction points, where steel bolts are used to clamp the mortises firmly around the tenons.

The bike is shipped disassembled, with a hex wrench and instructions that guide the buyer as they put the frame together.

City Vanture riders can choose between five levels of motor assistance
City Vanture riders can choose between five levels of motor assistance

Depending on who's looking at the joints, the protruding bolts may or may not be more visually attractive than aluminum welds. Additionally, Vanpowers claims that they're stronger than welds, plus they make for a straighter frame (albeit by fractions of a millimeter) and a smoother ride.

Lego-like frame aside, the City Vanture is much like most other ebikes. It has a 350-watt rear hub motor, which augments the rider's pedalling power up to a top speed of 25 mph (40 km/h) in the US version, or 15 mph (24 km/h) in the UK/EU model. That motor is powered by a 36V/7-Ah lithium-ion battery (located in the down tube), which should be good for a range of approximately 50 miles (80 km) per two-hour charge.

The City Vanture is being offered in 11 frame colors
The City Vanture is being offered in 11 frame colors

Some of the bike's other features (depending on the package) include a stem-integrated LCD display; Magura hydraulic disc brakes; a Gates Carbon belt drive drivetrain; plus DT Swiss rims with 700 x 28c Maxxis tires. The whole thing reportedly tips the scales at 34 lb (15.5 kg). We're still waiting to hear back about gearing.

Should you be interested, the City Vanture is currently the subject of an Indiegogo campaign. Assuming it reaches production, a pledge of US$1,399 will get you one – the planned retail price is $2,399.

It can be seen in action, in the following video.

City Vanture, a Refined Customizable Road E-Bike

Sources: Indiegogo, Vanpowers Bike

View gallery - 4 images
7 comments
7 comments
paul314
If they could use the mortise and tenon sets to allow for frame customization that would be really cool. It also likely saves them a whole bunch on shipping.
windykites
The framework could be glued together instead of bolted. Or have a bayonet type fitting as in light bulbs (BC type)
michael_dowling
Good idea,but you would have to check the tightness of the bolts on a regular basis. My new office chair suggests you snug up it's bolts once a month.
jerryd
I call this sleeving or socket and tube, certainly not M+T.
I do like the castings as enables people to design their own and glued in, very strong and cuts the welding weak points, labor. Since not welded, can be thinner, lighter.
rlseifer
A little Loctite or thread locker should resolve any issues with fasteners coming loose.
IvanWashington
for those of us who live where the pavement is busted up, it needs fatter tires and at least a front suspension/seat post shock absorber.
anthony88
Two hours for coffee?! On another point, do you have to tighten your nuts before getting on this bike?