Z Frame Fixie Concept by JeongcheYoon Drive Side

Designers and  have released some fancy bicycle concepts lately, like the flying bike, the Porsche 911 bike and BMW folding bike.

Just released by Jeongche Yoon is a fresh fixie concept with Z-shaped frame. The downtube transitions into a seatstay instead of ending at the traditional weld to the bottom bracket. To allow for this, Yoon hollowed the seat tube for the downtube to pass through. A bolt connects the seat tube and downtube for frame stability. On top of the interesting frame design, Z-Fixie rocks an integral tail light, bullhorns, and, for that uber hipster look, non-machined Aerospokes.

Shown above schemed chrome and black, Yoon tossed some red and white into alternate designs after the break…

Z Frame Fixie Concept by Jeonche Yoon Freewheel

Yoon describes the bike:

Z-FIXIE is a fixed-gear bicycle concept with polished Z-shaped frame.

The top tube, the seat tube, the bottom bracket and the chain stays are connected onto the Z-shaped frame. The down tube and the seat stays straightly cross through the seat tube. The frame is designed for a simple and urban look meanwhile keeping high stability from traditional bike structure.

It is completely compatible with current components in the market, and is perfectly harmonized with the integrated rear lamp as well as aero spoke wheels.

Z Frame Fixie Concept By Jeongche Yoon Upper Drive

Z Frame Fixie Concept by Jeongche Yoon Rear Bulls Z Frame Fixie Concept by Jeongche Yoon Chrome

Z Frame Fixie Concept by Jeongche Yoon Gradient Red Black

Z Frame Fixie Concept by Jeongche Yoon Red Black



  1. A guy I worked with built a Ti MTB with this configuration. We called it the bowtie bike – it was really cush to ride – until it snapped at ‘the knot’.

  2. Alex, you might be referring to the Ibis Bow-Ti. It was a pivot-less take on the URT designs which were in vogue at the time.

  3. This is what happens when you have an industrial designer make things without an engineer who’s willing to say “no” backing him up.

  4. “Nothing new under the sun…”

    Looking at the mad fixie, the frame is 2 triangles (assuming the head-tube is a single point) joined at a coincident point. Which from an engineering point of view is absolutely, totally, 100% stupid. The 2 trianlges are fee to pivot around that joint, and if they don’t its because its massivly over-engineered.

    The ibis may also be 2 triangles, but is arranged very differently, pivoting due to the flexibilty of the ti tubing, not due a shoddy design.

    “This is what happens when you have an industrial designer make things without an engineer ” +1

  5. totally…. “If a design is a rendering without a working prototype, it usually can and should be ignored.” +1

    If you want to really have a good time making comments on concept bikes, check out the International Bicycle Design Competition, run from Korea or Taiwan. There are so many bad concepts out there that you could spend all day writing sarcastic comments about them and never catch up!

    an industrial designer

  6. As an industrial designer with a healthy appreciation for physics, this makes me sad. Given that the downtube is almost purely in tension and the seatstays are purely in compression, combining them into one (pin-jointed!) element is not a great idea. Looks neat, but you could have the same visual impact with a much more neatly sorted structure…

  7. Oh, for the record – I’ve had very good experiences with some very talented ID guys. Some of them regularly kicked out designs that needed little to no engineering after the fact (besides some minor tweaking, DFM, and materials input, the normal stuff). I’ve also worked with guys that aren’t just Form over function, but Form only… they kick out designs that look like the above.

What do you think?