Originally Posted by
Duragrouch
I agree with all. Yeah, just needs (I think) a 33 or 34 chainring to get down to 20 gear inches. But for that, needs a different crank, no bigger than 110 BCD. Discs... I don't know if that SA hub is available for discs(?) But, I've considered if just a front disc would be enough for long descents, if Bromptons use a 100mm OLD front hub (my Dahon is 74mm fork, so would need a 20", 100mm disc fork, I've yet to find one aftermarket to retrofit).
Just, as usual, wishful thinking... 
Originally Posted by
Jipe
This graph is erroneous.
the 4s ans 12s are supposed to have the same 50t chainring and the IGH has a 1:1 ratio on its second/mid gear, meaning that with the same cogs 4s and 12s on second hub gear should have the same gear inches while on the graph, the gear inches of the 4s are longer than the gear inches of the 12s on its second hub gear!
Then you had better call Brompton ASAP, since THEY'RE the ones who created the chart that YOU'RE stating is "ERRONIOUS". Watch the video (apparently you DIDN'T???), give em' a call.
Sturmey-Archer offers disc brake versions (6 bolt) for their standard IGHs, but, and it's a big but, Brompton uses an exclusive-to-them super wide range three-speed hub on their 6-speed models AND this new 12-speed model claims to use yet another different exclusive wide range hub.
So, no disc brakes for you.
I want my 8 speed IGH and disc brakes!!! 
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