12/15T on BWR hub

For discussion of Brompton bicycles.

12/15T on BWR hub

Postby Bee on Mon Sep 18, 2017 1:59 pm

Hello all,
My Brompton hasn't even, quite, made the ordering process yet, but I'm only holding off hoping that the 2018 bikes will offer some new colours... which might prevent me blowing most of my Cyclescheme saving on raw lacquer :oops:
When I do order my new Bee, it'll be an M6 L or R with the -12% gear option. My spreadsheet tells me that the gear distribution with the stock 13/16T is a bit lumpy, and that the lumps could be smoothed away very nicely by swapping the standard 13/16T sprocket set for 12/15T.
So, the question is, is this possible? Using only Brompton parts? Or would I need 3rd party sprockets/spaces etc? If it is possible, I wonder why Brompton haven't adopted the 12/15T as their standard for 6 speed?
What is lost at the hill climbing end could easily be regained by fitting a smaller chainring. Thorn produce 130mm BCD 5-arm 3/32" chainrings with 38,39,40,41,42,43,44,.... teeth, available at SJSC. I assume there would be no problem swapping the stock chainring for one of these?

Looking forward to joining the fold....

Bee -- or rather, soon to Bee.
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Joined: Tue Sep 12, 2017 8:14 pm

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