No announcement yet.

Rebuild -Sturmey Archer RSX-RK5 IGH 5-speed

  • Filter
  • Time
  • Show
Clear All
new posts

    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

    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 Interesting that you can't swap them out but they use the same parts?



      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.


        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.


          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.


          • 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:

            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.

          It's no wonder Sturmey Archer doesn't recommend any of their hubs for Power Assist but it is understandable. When running with modest power some Internal Geared Hubs are dead reliable but as soon as you start putting 1000 watts through any of them the wear & tear & subsequent warranty claims go up. Even Rohloff goes as far as not covering their hubs if you run out of the recommended chainring /sprocket ratio. Shimano 8 speed Nexus hubs have been running with moderate Power Assists from manufacturers for donkeys years but typically 500 watts or less. My own Alfine 11 has seen 6 years of trouble free use with a 500 watt Mid Drive but I am careful to maintain it regularly & shift gears with care. Another consideration is whether you are feeding a lot of power through your hub with a cadence or torque sensor. The cadence sensors can tend to keep adding power while at the same time you are shifting gears & that can lead to some nasty gear crunches. The Torque Sensor Mid Drives tend to stop as soon as you stop pedaling making your shifts much less nerve wracking. Shimano now has a hub specified for Power Assists called the SG-C7000-5D for use with their STEPS Mid Drive & Kindernay also has their 7 speed model for roughly $1000.


            Welcome back Daytriker.

            I saw that 7-speed Kindernay recently (always looking for/at alternatives), but winced at the price. Although, for many of the new, thru-axle-only framesets, it (and the 14-speed) would be the only IGH possibility. IMHO, the Rohloff thru-axle spacer mess is a kludge at best.

            ... Still hate the Kindernay shifter design.
            Last edited by ncmired; 01-01-2022, 03:23 PM.


              Is this hub actually in production at sturmey archer? Or sunrace? I can’t find it anywhere. RSX-RK5?


              • ncmired
                ncmired commented
                Editing a comment
                AFAIK, it had a very limited production run and never made it into the Sturmey Archer / Sunrace catalog. To cost effectively replace a broken one, maybe the 170mm wide SX-RK3 3-speed cruiser hub:
                Last edited by ncmired; 03-14-2023, 02:50 AM.

              Ecocycles has NOS Nuvinci 171B CVT hubs. Rated 130Nm torque. With recommended 2:1 cogs that's 260Nm at the motor. 190 ft#. Cheap too.

              I hope you don't have to carry your bike up the stairs. It's very heavy. 8 steel golf balls drive this thing.


                i am new to internally geared hubs but am seriously considering putting one on a Surly Ogre frame. 145 knot boost spacing. and i think this stated it only has 135 axel. does something like this carry any validity. middle gear straight thru with -33 pct down and +33 pct up.
                Click image for larger version

Name:	Screenshot_20230728-161124.png
Views:	513
Size:	268.8 KB
ID:	163586
                think there would be alot of overlap and lower third maybe useless unless it could help pull a straighter chainline in lower gears.
                any thoughts? thanks


                  doing more research it appears that most IGHs that I am seeing are designed around 135mm rear spacing and there are issues with slop in the spacers when used on a 142/148 gnot boost spacing. would this be a correct assumption? Some seem to be okay with it.


                  • Mike_V
                    Mike_V commented
                    Editing a comment
                    From my experience, keep researching Rodney because: { It's inexpensive } &
                    The (3) vintage ~1960s Sachs IGHs that I collected require very specific bicycle frame features and dimensions that, I surmise, were specified by a European bicycle manufacturer. At that point I stopped my plan to build IGH eBikes because frame building is not for me and I will eventually sell my collection of IGHs. FWIW Good Luck Mike

                  • Mike_V
                    Mike_V commented
                    Editing a comment
                    Horizontal dropouts maybe required for example, with the requisite and robust chain adjustment mechanisms

                  Originally posted by Rodney Bush View Post
                  doing more research it appears that most IGHs that I am seeing are designed around 135mm rear spacing and there are issues with slop in the spacers when used on a 142/148 gnot boost spacing. would this be a correct assumption? Some seem to be okay with it.
                  Slop wouldn't surprise me, along with the nuts loosening up and everything else, as the axle rotates because of the planetary hub torque twist. You may want to look over what acidx came up with, here.
                  Last edited by ncmired; 07-29-2023, 11:01 AM.


                    Try Loose Screws bicycle parts.

                    The have a bunch of axle stuff. Maybe you just need a couple extra jam nuts or some serrated washers to get you going.
                    Maybe McMaster Carr has some spacers to put behind the jam nuts.
                    McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.