Automatic Hubs - 650B or not

Automatix uses centrifugal force to shift it at a particular speed -- and so, the hub doesn't annoyingly shift every time the coaster brake is used.
The speed at which the hub shifts may need adjusting. That is relatively easy to do, though it requires disassembly of the hub.

Haven't Sram stopped all IGH manufacturing? Not sure on the longterm spares availability.

I had one of those, I could get it to change in the first revolution, was more annoying than anything else and bare heavy.

I had a hub working on the same principle on an old Motobecane folding bike from the 70s. Made by Shimano. The centrifugal device was located in a plastic flange on the drive side of the hub, bigger than the hub itself in diameter.
It was a pain, because if you had gained speed and had arrived in high gear, you needed to decelerate significantly to switch back to easy gear, losing your precious momentum when approaching a hill...
Was fun though, somehow, as a curiosity...

I've test ridden the Urban Racer Sacha White was riding when Speedvagen was last in Europe (csb). I found the hub surprisingly good, and the coaster brake was more efficient than the old Czech one I once briefly owned.

I have built my bike with an automatix, it took a lot of love to get it too shift at the perfect rpm. However now that it is dialed, it is incredibly smooth. Setup: 38t(34t if I don't sport for a while) front, 19t back, gear-up at 18kph. The 18kph is perfect for cycling with friends or going up a reasonable grade. I would recommend it if your really interested. However when mine fails, I'm installing a 8speed alfine hub(with the possiblity to upgrade to di2)

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