That is a major addition of weight, the main reason that Brompton dont supply them as standard.
The chainring is kind of small ... isn't it?
What is the smallest cog available for the Nexus hub?
Then again, the chainring might be bigger than I first thought.
Why Brompton don't fit Nexus gears has nothig to do with the weight of it compared to a 3 speed..it is because the management of the company have their heads buried in the sand and believe they don't need to develop a good product..into a first class one...
Besides..a Nexus hub has a width of 130mm..the 3 speed hubs are only 110mm...but again..all down to shortsighted management..Once Britain made wonderful motorbikes...exported all over the world...but didn't invest in new product development ..and they had the same type of management as Brompton have..today..blind..!
in my friend's case, if he wants to stick with the original chainring, I think he might put a 16T cog, and probably get a wide range of gears, rather than only 'lows' and not much 'highs'
Adding a Schlumpf Mountain drive crank for Bromptons works well for me,
54 x 15 on an AW3 planetary low is 21,6t equivilent.
range is: 77.1, 57.9, 43.4, 30.8, 23.1, 17.4 ,
range could be higher with the 13 or 14t on the hub.
flicking the trigger shifter is quickly done, to switch both range, heel button,
and gear, at the same time.
Last edited by fietsbob; 11-11-10 at 10:07 PM.
My first bicycle was a three speed Dahon Piccolo and I was able to ride that bike for over 5 thousand miles climbing hills of all sorts! And walking up others!
"When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.
"Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008
I so happen to have a 13T Brompton sprocket which I shaved down to 11/128" and mounted on a Nexus for this very purpose. Alas I decided not to go through with the project (it wasn't for a Brompton).
So I'm looking to sell my custom 13T Nexus sprocket at a discount if anyone's interested (I hate to waste it and those Brompton sprockets aren't the cheapest).