Lightweight hub gear setup- Mtbr.com
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  1. #1
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    Lightweight hub gear setup

    IN the UK Singletrack there is some discussion as to what is the point of the Sturmey-Archer 3 speed hub with a freehub to take a cassette.

    That got me thinking. One of the needs on a fatbike is a very wide gear range because of the difficulty in riding on very soft surfaces. You can use a derailleur, but I would hate to try to take something as delicate as that where I take my bike. Many of us use a hubgear like the Alfine or Rohloff. The big problem with them is their weight being concentrated at the axle.

    Then I looked at the Sturmey-Archer hub S-RK5(N), a 5 speed with a spline fitting for the cog. It weighs 1160gms - considerably lighter than an Alfine or Rohloff, but has a lesser range of 256%



    Now consider this - set it up like a dingle speed. Max rear suggested is 22T and minimum is 12T, so if you had a 22F/22R and a 32F/12R , you would have a range that ran from 18" to 46" and from 48" to 123". That is just an example to show the range that would be available - I can't imagine trying to turn 123" on a fatbike

    The gear change would be the old fashioned loosen the wheel and shift the chain by hand - you would only be doing this at the trailhead after leaving the road and vice versa. Just like we used to do with the old flipflop hubs. 22F/23R and 32F/13R gives 17" to 44" and 44" to 114".

    Thus, wide range, low weight.

    (The cog combinations use the same amount of chain so a chain tensioner should not be necessary)
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  2. #2
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    I originally planned on using one of those with a Schlumpf for my Pugsley build. Unfortunately, they aren't available (in 9-spline version) the US.

    I have the regular 3-spline setup on my brompton and it doesn't seem to be too bad. I don't know how well in would stand up to increased torque.

  3. #3
    A Surly Maverick
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    These hubs are interesting VB

    Have you seen this one :- http://cgi.ebay.co.uk/NEW-Sturmey-Ar...item746af64132

    Internal 3 speed but will take an 8 or 9 speed cassette !
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  4. #4
    How much does it weigh?
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    I met a dude running one of those with triple ring up front.

    Said he was from BC in an area with lots of hills.

  5. #5
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    sounds perfect for a commuter/trail bike too.

  6. #6
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    Quote Originally Posted by Dr Feelygood ! View Post
    These hubs are interesting VB

    Have you seen this one NEW-Sturmey-Archer-CS-RF3-3-speed-Cassette-Hub-8-9-spd
    Internal 3 speed but will take an 8 or 9 speed cassette !
    Yes, I know about that one, but that would involve a derailleur, and I'll never fit one of those kludges to anything but a road bike.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

  7. #7
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    Quote Originally Posted by Velobike View Post
    Yes, I know about that one, but that would involve a derailleur, and I'll never fit one of those kludges to anything but a road bike.
    Yes I must admit I`m missing not having an Alfine on the Fat Klein

    BUT, I`m not defeated yet !

    Just lack of fettling time (and the fact that I`ve only just stopped finding aluminium grindings all over) is delaying things.......

    I do, however have a plan

    I bought a Mukluk rear (qr) adaptor to see if it could be `adapted`.

    Short answer, No it can`t....

    But it does make a good template
    Life IS a Beach and then you Corrode :)

  8. #8
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    Good idea. I still think there is nothing like a Rohloff.

  9. #9
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    hey doc, lateral thinking here. make a mukluk-ish 170->135offset adapter that simply screws itself onto the alfine's axle (acting as the nut).
    then just bolt the stupid adapter to the frame on that side.

    once you'd screwed it down the first time then you wouldn't need to adjust the alfine's cable run etc. and if you paid attention to where you started the threading it may not even be an issue at all.
    If steel is real then aluminium is supercallafragiliniun!

  10. #10
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    Quote Originally Posted by suba View Post
    Good idea. I still think there is nothing like a Rohloff.
    Yes. However I'm on my light fatbike quest, so everything is getting looked at.

    Including whether I need to man up and train hard, then I will weigh less and won't need gears on the fatbike = lighter me, lighter & simpler fatbike .
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

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