About the Sturmey-Archer RX-RK5 IGH


This infographic compares the gear ratio of the Rohloff 14 Speedhub to that of the Sturmey-Archer RX-RK5. Both are IGH hubs with disc brake flanges. The heavy-duty SA hub is also available with a 90mm drum brake (RXL-RD5).

Given that the rear tire, chainring, and cog are all the same size:
While the gear range of the Speedhub is far higher at 5.26:1 – compared to 2.43:1 for the RX-RK5 – that extended range is all in the lower gears.

The RX-RK5 has a higher top gear at 1.56:1 and it’s lowest gear at 0.64:1 compares to the Rohloff’s 7-8th speed. If one rides an eBike on the street the heavy duty RX-RK5 should work well for a fraction of the cost.

One can change the gearing, the chainring and or the cog, to make it more offroad or hill climb friendly.
For sure the 14 speed Rohloff is the cat’s meow. But to get a tough 5-speed IGH for about $125 – that is pretty attractive to me.

The 5-speed range of the Sturmey-Archer IGH series is indicated as “Designed for heavy duty use” and weighs 2000g according to the Sturmey-Archer website. Sturmey-Archer also offers an 8-speed IGH, that weighs in the “1860g-1880g” range. My thought is that the 5-speed SA hubs are a bit heavier and thus the moniker of “Designed for heavy duty use” is true.

One still has to understand that these hubs were not originally designed for electric power and being careful to use a shift sensor or to pause the power while shifting is essential to the health and long life of the IGH.

I will post more here in the future as I explore how the hub holds up over time.
October 20, 2017

Because the cruiser bike frame I am using does not have disc brake mounts, my first use of the 5-speed Sturmey-Archer hub is the 90mm drum brake version, the RXL-RD5. So far bedding in the shoes with the drum has not been as easy as I would have hoped. But I have not fully given it a chance to bed in. All the hardware is included in the box with the hub, including the shifting assembly and cable, and the cable and all the hardware for the drum brake – but not a brake lever. I only wish the black anodized version was available here in the US.