Flow Lab’s Sunny: NJS Heritage Meets 650b Adventure
A few weeks ago, I introduced you to Kaito, frame builder at Stratos. If you read until the end, you might recall me mentioning his side project; Flow Lab.
Together with Taiga and Oya, they have been shaping their vision for something new that I absolutely wanted to share on here. And now, with the official launch fast approaching, it was finally time to shine a light on this hidden gem from the Far East.
As a reminder, both Taiga and Kaito have been welding for Cherubim and Stratos, two renowned frame builders that need no introduction. They have the skills, but more importantly, they see the bigger picture to apply those skills in a way that could appeal to a wider audience.
In this article, I’ll talk about the first two generations of prototypes for the debut of the Flow Lab frame. This will be a quite simple overview of the concept before I get to review one in more details.
So! A red, a blue, what’s the difference? The red one comes from the very first batch of two, which have been ridden non-stop for over a year and a half. And the blue one is the latest prototype, which began its journey in the summer of 2024.
The concept here is simple, yet makes so much sense: Imagine a frame made from NJS tubing, crafted by builders trained in the finest lug-welding techniques.
Now, picture that frame with NJS-inspired geometry, 120mm track ends, but fitted with wide 650b tires and cantilever brakes.
That’s it! You’ve got Flow Lab’s first frame: the “Sunny.” An NJS-like track bike, still with a one-inch steerer, Kasei tubing, lugs used on NJS frames, and more, but built for big tires and wild rides!
With the second prototype of the Sunny, the Flow Lab team made some tweaks to the seat and head tube angles, and reinforced the seat-stays to better handle the forces from the cantilever brakes. If you want to get even more technical, the frame is a blend of Kasei 019 and 022, with custom seat stay caps, also introduced in this second prototype.
Personally, I’ve always loved the way NJS bikes handle. And it’s no surprise since many of them are built by literal framebuilding legendary grandpas who were geniuses at their craft.
And for my personal take, I think this thing rides amazingly well. Even with meaty tires, it’s a frame that stays well balance and dynamic. The geometry has truly been designed for big 650b tires, with a maximum clearance of 42mm. Of course, you could swap in 700c wheels, but that would limit you to 23mm tires. Clearly less fun…
With semi-slicks, this bike felt like riding on a little cloud, super comfy and perfectly suited for a single-speed setup. You could definitely use it as a Tracklocross bike, and both prototypes have been ridden like that from time to time. But to me, it really shined as a chill commuter bike for sunny days.
On top of that, it’s a fairly easy bike to build, with a standard 27.2mm seatpost, 1” quill stem, and a basic 68mm bottom bracket shell, pretty much everything you should already have at home.
Unfortunately, I’m not yet able to share the prices, but when I discussed with the three founders I thought it was surprisingly affordable for a Japanese hand made frame, build with a quite limited production capacity. Be assured that I’ll get my hands on one of these for a more in depth review as soon as I can. In the meantime, you can follow their progress on Instagram to get some updates: @flowlab_log
Good people only make good bikes
🔗 : Flow Lab
🎞: kodak Color Plus 200
📷: Leica M6
📍: Yamanashi
