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Rebuild -Sturmey Archer RSX-RK5 IGH 5-speed

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    Rebuild -Sturmey Archer RSX-RK5 IGH 5-speed

    Who has access to OEM parts & can rebuild a RSX-RK5 IGH (Luna Fat BABE)? Thanks, Rick

    #2
    I have a Bafang G510 1000w Mid Drive, Gates Belt Drive, and a 5 speed Sturmey Archer RSX-RK5 which keep intermittently slipping while I am riding. I have checked all the boxes suggested by Luna cycles (Thanks, for the posting) - my belt is definitely not slipping so therefore it must be the hub.

    A few things I have found out.
    1) Sturmey Archer Sunrace USA said that their internal hubs are not designed to be used on e-bikes. This is what they said. "We do not make a hub I would recommend for use with a high power mid drive motor and I am not aware of one made by our competition either. Even traditional derailleur based drivetrains do not live long on these new powerful e-bikes. The chains and cassettes tend to wear or break much faster than a traditional pedal operated bicycle. " "The hub is not designed to be used in conjunction with mid drive motors. Unfortunately many Chinese e-bike manufacturers just purchase items without asking or testing prior to spec’ing the product. It was designed with the idea of using front or rear hub motors."
    2) You will not find a RSX-RK5 hub in the aftermarket. ( Rather than rebuild I was hoping to purchase a new hub, and swap the gears.)
    3) The gears are compatible with the RX-RK5 and can be purchased from www.sturmey-archerparts.com. Interesting that you can't swap them out but they use the same parts?


    Comment


      #3
      Interesting.

      Guess they don't consider Rohloff or Nuvici/Enovolo competitors? I believe both of them mention E bikes in their catalogs.

      Not making me want to buy anything with one if you can't easily buy a replacement replacement if you wanted one. Or are they saying that the RSX is the OE version of the RX and internals are the same so this would still get you what you are after?

      I have mixed feelings about IGH with mid drives. Mine was just a 3 speed Nexus and I was in the process of replacing it with a cassette anyway due to the limited range not meeting my needs when I was starting to get hints of issues with it. I wasn't slipping but it didn't seem to be shifting when it was supposed to and made some pretty bad sounding noises on my last ride. If I ever consider using it again I will tear in and see what was going on and like you I had the idea to just buy a replacement and transfer the guts assuming its wasn't the actual hub housing that had the damage.

      I will have to look for it again but I recently stumbled on a demo video of an IGH that fit into a cage sort of thing that looked pretty neat. You actually built the cage into the wheel and the IGH part slid in. One of the selling points was if you had multiple wheels you didn't have to buy multiple hubs you could just swap. I think they also mentioned E applications. I think I got distracted by another suggested video so I didn't look to see where they are sold or what they cost but it seemed interesting and they were physically pretty large so seemed like a good chance they were durable. I'm sure too heavy for some hardcore riders but us E people tend to have a lot of other weight issues so maybe a good fit for us.

      Comment


        #4
        Responding to 73eldo.

        I think that the IGH you saw on a video was an SRAM (?), I saw it also. They touted the 'easy repairability of the drive'. They suggested that when it wore out, or broke, you just bought a new one, removed the gears from the new housing and installed them in your old housing. Presto, no lacing in of the housing into the new wheel! I can't find that video now. SRAM seems to have dropped all IGH production but you might find some 'new old stock' on ebay.

        Others in this string:
        I agree that current IGHs are problematic when coupled with big mid-drive motors that directly put stress on the tranny in an 'instantaneous' manner; that little bit of delay in ramping up the torque (from a front hub motor) seems to make a big difference in IGH longevity.

        As an example, I own a FAT ebike with a Shimano NEXUS-8 IGH it has 6200 miles on it after 5 years of use. The chain and front sprocket are very worn out, but I have a nearly perfect, long chain line and the chain does not skip yet. The IGH is the Shimano 'red-band' heavy duty version (now discontinued). My bike is powered by a 350W Bafang front hub motor with 3 electronic levels of assist. I have never heard a peep out of that IGH or the motor. An amp draw test indicated that the motor is more like 500W at top speed, it has never run hot. I ride it on flat suburban streets in Southwest Florida, often at ~25 mph (with lots of pedaling). I rarely need to shift, using mostly 7th and 8th gears, even at start-up. I just push off lightly to give the e-motor & tranny a boost, and reduce wear.

        Given my riding pattern I have thought that I should just install one rear sprocket and dispense with my IGH!!!! If it breaks I will not fix it, just get a free wheel hub.

        Perhaps one gear is a simple option for the posters above? I understand that in very hilly, or intermittently windy areas, that might not be possible to eliminate the gears, but you might be underestimating the torque band of your motor and how little it really needs gearing.

        Comment


          #5
          Shimano also supports the idea of swappable internals, and sells the "guts packs" for most of their IGH hubs. I've got guts packs for my Nexus and Alfine 8-speeds on the shelf, but have not had to use them.

          I suspect the video 73Eldo saw was for the relatively new Kindernay 14-speed hub. Here's the standard wheel cage, followed by a fat version and sprocket extension. The hub is the same for both:

          Click image for larger version  Name:	Kindernay-XIV-MTB-internal-gear-hub_14-speed-thru-axle-mountain-bike-internally-geared-hub_removable-SWAP-shell.jpg Views:	0 Size:	128.8 KB ID:	119448






          Click image for larger version  Name:	1-XIV-Fatbike-complete-hub.jpg Views:	0 Size:	30.9 KB ID:	119449


          The sprocket chain/belt line is not ideal for BBS motor use, and the shifter is hydraulic, blocking the use of a shift detector. The Kindernay's gear ratio range is slightly wider than the Rohloff, and the complete kit cost is I think higher.

          What I'd like to see is a reduced cost, 7-speed version of the Rohloff that retained the current, easy to manage chain/belt line.
          Last edited by ncmired; 12-24-2020, 06:17 PM.

          Comment


          • 73Eldo
            73Eldo commented
            Editing a comment
            That was it. For the same price as rohloff you would have to really want that swap feature.

            Do the Shimano or SA hubs have anything that is likely to get worn or damaged in the shell itself or would being able to replace the guts get you back on the road 9/10 times? I used to rebuild the 3 speeds but it was 30 some years ago last time I had one open. I remember hating the Shimano because they had more small parts that were difficult to hold in place during the assembly process. I remember the SA's being pretty easy to work with. No idea if either of them has changed a lot since then. My guess is the 3 speeds would not have changed a lot but I would think the higher number of gears would be a lot different design.

          • ncmired
            ncmired commented
            Editing a comment
            Hi 73Eldo - you asked, "do the Shimano or SA hubs have anything that is likely to get worn or damaged in the shell itself or would being able to replace the guts get you back on the road 9/10 times" - I think it depends on the hub.

            The 3/5 speed hubs are usually single stage, where the 1:1 speed mechanically locks to tracks or castings in the hub shell. There are probably failure modes on these hubs where the hub shell could get damaged.

            The 1:1 speed on the two-stage (4-speed with a 2-speed high/low) 8-speed Shimano hub does not lock to the shell. While the guts are much more complicated. I've read opinions Shimano tailored the design for the guts swap to make it easier on the dealers (repair and/or relube).

            As I've posted elsewhere, I've had no issues with my 8-speed Nexus/Alfine hubs. Shifting is quick and easy, and I shift under full power, with a shift sensor and the throttle locked: https://electricbike.com/forum/forum...-adjustability

            I've not used or owned any of the current Sun Race -> Sturmey Archer hubs.
            Last edited by ncmired; 12-22-2020, 11:13 AM.
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