Sturmey 8 speed on a Brompton?

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Hypothetical consideraton. I have a Sturmey 8 speed hub - the slightly later wide ratio one, with the narrow axle. It’s currently built into a Brompton sized 16” rim and fitted to very early Moulton I rescued from the back of a garden shed many years ago (if you know your Moultons, it’s a pop-riveted frame with the high mount point front rack… makes it about 1962 I think). Could I just pop it into my Brompton (removing all the sundry gear shifting stuff apart from the chain tensioner), and have it working, or are further adjustments necessary to get it going? I know there used to be “8 speed kits” for the Brompton so I wonder if there are any specific issues to attend to.

The hub is a weighty piece of machinery so this would probably go on a different (another! 😆) B. to my beloved S6L.

 

[Gunk]

It is possible but not much of a benefit over the standard Brompton 6 speed.

The Brompton OLN is 115 and the 8 speed hub is 120 so you would have to cold set the rear triangle for it to fit.

 

[wafter]

I keep getting impure thoughts about hubs with more ratios, but tbh I find the standard 6 speed setup spot on; even if the gears are wider-spaced than you'd expect on a standard derailleur setup on a full size bike.

 

[StuAff]

Hypothetical consideraton. I have a Sturmey 8 speed hub - the slightly later wide ratio one, with the narrow axle. It’s currently built into a Brompton sized 16” rim and fitted to very early Moulton I rescued from the back of a garden shed many years ago (if you know your Moultons, it’s a pop-riveted frame with the high mount point front rack… makes it about 1962 I think). Could I just pop it into my Brompton (removing all the sundry gear shifting stuff apart from the chain tensioner), and have it working, or are further adjustments necessary to get it going? I know there used to be “8 speed kits” for the Brompton so I wonder if there are any specific issues to attend to.

The hub is a weighty piece of machinery so this would probably go on a different (another! 😆) B. to my beloved S6L.

Ben Cooper (aka Kinetics) used to do a Sturmey kit conversion, not an option from him now but he still does kits for Alfine, Rohloff, Kindernay... also he'll sell you a new, wider triangle. Sure he'd know what else you'd need, and perhaps have it in stock...
https://www.kinetics-online.co.uk/folding-bikes/brompton/brompton-rear-triangle/

 

[berlinonaut]

Could I just pop it into my Brompton (removing all the sundry gear shifting stuff apart from the chain tensioner), and have it working, or are further adjustments necessary to get it going? I know there used to be “8 speed kits” for the Brompton so I wonder if there are any specific issues to attend to.

You could. There are some mods necessary to the chain tensioner, but these are no big issue.

It is possible but not much of a benefit over the standard Brompton 6 speed.

Depends. You do have way more attractive gear steps with the inner 6 gears and you have one single shifter in opposite to two with the BWR. On the other side 1kg of additional weight and a gearbox that follows the S/A Sprinter in the sense that it is a very sensitive piece of kit in terms of adjustment.

The Brompton OLN is 115 and the 8 speed hub is 120 so you would have to cold set the rear triangle for it to fit.

No need for that. You can easily bring it to 112-114mm OLD.

We had an interesting discussion about this hub on a Brompton recently on the German forum - possibly this might be able to deliver some insights: https://bromptonauten.cc/threads/8-gang-nexus-vs-s-a-xrf-8-w-im-vergleich.723/

 

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Apart from the weight and the slightly sensitive shifting there is a lot to like about the hub: direct drive is bottom gear, gears shift sequentially (not that the Brompton half-step gearing has been a problem for me) and you have a super low bottom and a high top with a cluster of evenly spaced gears in the middle. It can sound like someone starting up a circular saw though.

I had to make the hub narrower anyway, my Moulton has I think 110mm rear spacing and Moulton forks are notoriously fragile so I was very cautious about any significant cold setting. Eventually I switched the original series 1 forks for the much more robust series 2 version.

 

[Fastpedaller]

I can see the possible benefit compared with other options. The 3 speed hub with 4 speed derailleur..... how many different ratios does it give, as some may be close duplicates? I have toyed with the idea of the 'kickshift' 2 speed SA gear, but decided it just provides a huge jump in ratio and no real advantage. It's a conundrum, as adding weight makes it more difficult to carry the folded bike, but of course if it provides the desired gear ratios then the benefits may outweigh (pun intended) the disbenefits.