A tidier back end

One of the things that bugs me about the Sturmey Archer S-RK3 hub is the size of the drive side guide nut, which, when combined with a non-turn washer and fulcrum lever, ends up sticking out of the side of the bike quite some way. It just all looks a little clunky. So I got thinking.​

Because spare parts availability is so comprehensive and many of the parts from different Sturmey Archer hubs are cross-compatible I thought that I’d see if I could neaten things up a bit. The first thing I did was to switch from using a fulcrum lever as the cable stop to a chainstay fulcrum clip, which quickly helps to neaten up the bike. This is relatively easy as both options come supplied with the hub. However, taking things any further than this requires a bit more experimenting...

I started by swapping the stock guide nut (HMN129) with the short version (HMN420). However, if you just stick this on the end of the standard axle with the normal non-turn washer then the interrupted thread of the nut prevents it from being tightened.

So my next move was to replace the standard 185mm long axle (HSA864) with something a bit shorter.  My first thought was to use the 175mm long axle that is listed as an option for S-RF3 hub on the Sturmey Archer website, but for whatever reason they don’t sell this as an individual item in the UK. So instead I thought I’d see what I could do with a 163mm long axle and gear indicator chain from an S-RF3 hub (HSA440 and HSA315), which, unlike the 175mm axle, are available on their own.

The main challenge with using the 163mm long axle is that it only leaves 12mm of exposed axle on the drive side and 16mm on the non-drive side once the 135mm O.L.D. (Over Locknut Dimension or space between the dropouts) has been accounted for. With dropouts that are approximately 8mm thick this didn’t leave enough room for a non-turn washer and a nut.

To get around this issue I figured that I could free-up some space by placing the non-turn washers (HMW518) on the inside of the dropouts, replacing a couple of the locknuts. As standard the hub comes with three 4.8mm locknuts on the drive side, while the non-drive side has a single 4.8mm locknut along with a 6.4mm one. Given that in some configurations the S-RF3 hub makes do with a single locknut on each end of the axle, removing a 4.8mm locknut from each side seems reasonable without affecting the hubs operation and it just so happens that the standard non-turn washers are almost exactly the same width. This still doesn’t leave a great deal of thread for the axle nuts, but they don’t need to handle a great deal of loading with my horizontal dropouts and so far they seem to be holding up just fine.

If, for whatever reason, you may need to swap a non-turn washer for one of the 6.4mm nuts, then you may find it helpful to use a pair of HMW534 washers instead, as these are almost exactly the same width.

Below are a couple of before and after photos that illustrate the change.