OverviewHere is the 4 prong Sturmey archer wrench to open up a Sturmey Archer 5sp hub. With this wrench, you could open up the hub for service or core replacement.
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It has 4 prongs, unlike the cheap imitations with 2. It is rugged and was used to successfully unthread a core that had been highly torqued, due to thousands of miles under a 750 watt motor.
But separately, Biktrix sells bikes with Sturmey archer hubs, but makes no effort to help us keep them up. Local bike shops will mostly not touch them, and Biktrix apparently has no parts inventory or on line help. They DO have instructions on core replacement, but they don't sell the cores, and you can't find them anywhere else. The bigger issue is that the RX RK5 Sturmey Archer hub is sold for e bike use by Biktrix, but Sturmey Archer has explicitly stated that they should not be used on e bikes. Biktrix did not mention this 4 years ago when I bought my e bike from them.