The simplest way to describe a Möbius strip is a surface with only one side and only one boundary. You can create one by taking a strip of paper, giving it a half-twist and taping the ends together.
Möbius is also the name of a frame design that Mathew Amonson of Brooklyn’s Airtight Cycles has been developing. Like the geometric mathematics of August Ferdinand Möbius, who discovered the formula in 1858, the asymmetric seat stays of Mathew’s frames are a small triumph over physics.
Mathew studied frame building under Koichi Yamaguchi, whose own bikes are well known for their free-thinking designs. Yamaguchi experimented extensively with asymmetric time trial frames and his influence has obviously rubbed off on Mathew.
This version is called the Möbius 650c Kyudo, or the way of the bow — the modern Japanese martial art of archery. It’s an apt title for a bike built for a Japanese customer, whose height determined the geometry and also the choice of 650c wheels.
The seat tube was trimmed at 46cm, but using 650c wheels helped Mathew maintain a high performance geometry. The head tube angle is kept at usable 74°, and since it will be ridden on the street, it’s nimble, yet stable.
Mathew built the wheels himself, using Dura-Ace track hubs and Velocity A23 Rims. A Nitto stem leads out the cockpit, mounted with Paul E-Levers that haul up two TRP time trial brake calipers — the rear is hidden behind the bottom bracket shell.
The frame is made from Columbus tubing, with Llewellyn fork dropouts and chopped Columbus track ends. Eyes are immediately drawn to the completely custom seat tube cluster, which looks like it would’ve tried the patience of even the most experienced frame builder.
So what’s with the asymmetric seat stays? Mathew tells us: “The reasoning behind the offset ‘Möbius’ stays is that it makes the drive side stiffer when pedalling. By nature 99% of bikes are slightly out of balance because the drive is on one side and frames are not built to account for it.”
“A couple of high-end manufacturers account for it,” Mathew continues, “by increasing the diameter or thickness of the drive side seat stay. I do it by offsetting them. When you account for the drive side imbalance, you lose less of your energy to frame flexing.”
It sounds good in theory, but it also looks amazing, which accounts for a lot. Check out Mathew’s other Möbius frames on the Airtight Cycles website.
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