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  1. #1
    Junior Member
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    Brompton 2 to Single Speed Conversion / Gearing

    Hi all,

    I currently have a 2 speed brompton and after having the cable snag a few times causing me to be stuck in the larger cog (which i never use) i decided just to remove the whole derailleur assembly (keeping the tensioner in place) so it permanently sits in the smallest cog which I'm very happy with but would like to make it look a bit more 'factory planned'.

    I've already had the gears off the bike and back on for cleaning but know nothing of bike terms and how to gain measurements, can any one advise what spacer id need to buy in order to remove the larger of the 2 cogs entirely? id also like it to take into account that i didn't want to use (although I'm guessing many will advise against it) the plastic guard that sits nearest the wheel on the freehub.

    lastly is it possible to easily fit an even smaller rear cog still (than the 12) or a larger chain ring (than the 54) without too much fuss and cost?

    thanks

    Dan
    Last edited by danieledwards; 01-11-12 at 02:01 AM.

  2. #2
    Senior Member
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    Too many....................
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    From what I have read the wheels are the same. Here are some choices
    http://www.brilliantbikes.co.uk/48-brompton-chainsets

    http://www.brilliantbikes.co.uk/56-b...ts-and-spacers
    Speed Uno
    Dawes Kingpin 2speed

  3. #3
    Junior Member
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    thanks, i just had a reply back from brompton also confirming that it would be the QRSPRSTACK-BB1 - cheap as it is i didn't really want to buy the sprocket and was hoping to also remove the guard but at least there is a way - thanks!!!

    http://www.brilliantbikes.co.uk/brom...bb1-stack.html

    dan

  4. #4
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    Not sure if you could fit a larger main. As with all mods on a Brompton maintaining the fold is problematic.

    Again not sure if you could run with a smaller rear sprocket, if you could even find one.

    A 54T * 12T single speed gives you a 74" gear which I find about right for Cambridge which is flat and for me spins out at about 23mph.

    Regards

    Jerry

  5. #5
    Junior Member
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    Quote Originally Posted by jerrysimon View Post
    Not sure if you could fit a larger main. As with all mods on a Brompton maintaining the fold is problematic.

    Again not sure if you could run with a smaller rear sprocket, if you could even find one.

    A 54T * 12T single speed gives you a 74" gear which I find about right for Cambridge which is flat and for me spins out at about 23mph.

    Regards

    Jerry
    ah, I can just about get it to spin free on the pedals heading downhill from Picadilly to Marble Arch and then again on the run down to the Royal Mews

    still plenty enough to overtake everyone else on the commute (....aswell as the vehicles )

    dan

  6. #6
    coprolite fietsbob's Avatar
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    Putting the 3 speed chain tensioner on will let you exchange the pulleys
    to some different ones with sealed bearings .. rather than ,
    the unique setup of the 2 speed 2 cog chain tensioner. which is self bushing ,
    and has a skosh more friction.

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