• Posts
  • RSS
  • ◂◂RSS
  • Contact

  • Planetary gearing taken to excess

    August 21st, 2009
    bikes, transport  [html]
    The schlumph mountain drive bottom bracket with planetary gears looks pretty cool. It is foot actuated and allows a reduction of 2.5. I was curious what sort of gears it would give my bike so I calculated:
    front gear rear gear gear inches
    1 1 18.6
    1 2 25.5
    1 3 34.6
    2 1 44.6
    2 2 61.1
    2 3 83.1
    No wasted gears, a nice shifting pattern with only one double shift, as low a gear as I could want for a really steep hill or a really heavy trailer. A total range of 501%, which is almost as good as a rolholff's 526%. The schlumpf is rated for use with coaster brakes, and my SRAM T3 is tough enough for the schlumpf. But how to justify $.5K for a new bottom bracket?

    For reference, my current gearing is based on approximately 28 inch wheels (622mm rims, largeish tires), a 48 tooth front cog, a 22 tooth rear cog, and a SRAM T3 hub that offers 1st, 2nd, and 3rd at 73%, 100%, and 176%.

    Comment via: facebook

    Recent posts on blogs I like:

    The Gift of It's Your Problem Now

    Recently a security hole in a certain open source Java library resulted in a worldwide emergency kerfuffle as, say, 40% of the possibly hundreds of millions of worldwide deployments of this library needed to be updated in a hurry. (The other 60% also …

    via apenwarr January 1, 2022

    The container throttling problem

    This is an excerpt from an internal document David Mackey and I co-authored in April 2019. The document is excerpted since much of the original doc was about comparing possible approaches to increasing efficency at Twitter, which is mostly information tha…

    via Posts on December 18, 2021

    Experiences in raising children in shared housing

    Sometimes I see posts about people’s hope to raise children in a group housing situation, and it often seems overly optimistic to me. In particular they seem to expect that there will be more shared childcare than I think should be expected. Today I talke…

    via The whole sky October 18, 2021

    more     (via openring)


  • Posts
  • RSS
  • ◂◂RSS
  • Contact