26x2.1 (w/127mm cranks) Vs. 29x2.1 (w/150mm cranks) Ping.Mikefule

Discussion in 'rec.sport.unicycling' started by forget_your_life, Apr 27, 2006.

  1. hey there...

    besides the bigger wheel of the 29er dealing better with road
    Irregularities, what am i looking at performance wise?

    does 127mm cranks on a 26 offer better control than the 150's on the
    29er? or visa-versa? things like that.

    anyone is welcome to reply, i put Mikes name in the title because he is
    the champ of this stuff...


    --
    forget_your_life

    dream one dream many....
    *'R.I.P'
    (http://www.unicyclist.com/forums/member.php?action=getinfo&userid=502)*
    ------------------------------------------------------------------------
    forget_your_life's Profile: http://www.unicyclist.com/profile/4558
    View this thread: http://www.unicyclist.com/thread/48929
     
    Tags:


  2. Mikefule

    Mikefule Guest

    Flattered.:eek:

    Assuming wheel diameters of exactly 26 inches and exactly 29 inches.

    (Real sizes may vary slightly, even for a given tyre section.)

    127mm = 5 inches
    150 mm = just under six inches.

    Very simply, the 26 with 5 inch cranks has a crank:radius percentage of
    *38.5*% (5/13)

    The 29 with 6 inch cranks has a percentage of *41%*

    Or, for the 29er, the wheel is 29/26 = 11% bigger.
    The cranks are 150/127 = 18% bigger.

    So the 26 with short cranks will feel faster, but slightly less
    controllable in terms of mounting, idling and stopping.

    In reality, the difference between 41% and 38.5% is negligible: about
    6% which is less than one cog on a -road -bicycle.

    If I were choosing the two unis, I would swap the cranks. Put the
    longer ones on the smaller wheel for that full-on tractor effect, and
    the shorter ones on the bigger wheel for that barnstorming unstoppable
    rolling death effect.


    --
    Mikefule

    Last night another soldier, last night another child
    No one seems to worry, no one sees his mother cry
    They're just facts and figures on your TV screen
    Another child and another soldier, is peace just a dream?
    ------------------------------------------------------------------------
    Mikefule's Profile: http://www.unicyclist.com/profile/879
    View this thread: http://www.unicyclist.com/thread/48929
     
  3. Mikefule

    Mikefule Guest

  4. Mikefule wrote:
    > barnstorming unstoppable rolling death effect.




    all things being equal again with the tire (say 2.1) which will have
    the better "rolling death effect" a smaller wheeled 26" with 127mm's
    Vs. a large and in charge 29 with 165mm cranks?

    the smaller wheel of the 26" falls into smaller holes (so to speak)
    thus slowing us down but is it still faster than a bigger wheeled 29
    with "tractor" 165's? or does the roll over power of the 29" out due
    the smaller 26 with shorter 127's even though it has longer cranks
    (165mm)


    --
    forget_your_life

    dream one dream many....
    *'R.I.P' (http://tinyurl.com/vr86)*
    ------------------------------------------------------------------------
    forget_your_life's Profile: http://www.unicyclist.com/profile/4558
    View this thread: http://www.unicyclist.com/thread/48929
     
  5. Mikefule

    Mikefule Guest

    Well, I was criticised for posting it at the time, but this might help:

    http://www.unicyclist.com/forums/showthread.php?t=50840

    For riding cross country, with mud, long grass, short hills, gravel and
    general mixed terrain, 125s work well on a 28 with a skinny tyre, so
    should be magic on a 29er.

    Given the choice of wheels and cranks you have specified, I would put
    long cranks on the smaller wheel, and short cranks on the larger. It
    would emphasise the differences, and give each a distinctive role.
    Otherwise, you end up with two broadly similar machines, about a gear
    or so different.

    Most of my riding recently has been on a 28 with 114s. The
    terrain-crossing limits have been met by the tyre from time to time,
    but not by the crank:wheel ratio. (The tyre is a 23mm road tyre pumped
    to 130 psi.)


    --
    Mikefule

    All the world's a stage... and some of us are the horses pulling it, and
    there are far too many passengers.
    ------------------------------------------------------------------------
    Mikefule's Profile: http://www.unicyclist.com/profile/879
    View this thread: http://www.unicyclist.com/thread/48929
     
  6. The crank length : wheelsize ratios determine the "gear" of the
    unicycle, because the resulting number is proportional to the amount of
    "leverage" you have against the road. The higher the crank
    length:wheelsize ratio, the "lower" the gear: it'll be easier to turn
    the wheel but you'll go slower for a given cadence.

    However, it's not the only difference: larger diameter wheels roll
    better over bumps, and also have more stability due in part to their
    larger mass. I'd expect you to go faster on a larger wheel given the
    same theoretical "gear" due to these factors (and because it's
    difficult pedalling fast on tiny cranks in my opinion).

    For a concrete example:
    My friend Alan has a 20" uni with 80mm cranks. I have a 29er with
    127mm cranks, and a 36er with 150mm cranks. The highest theoretical
    "gear" is the 20" uni, but it's also the slowest of the three. The
    29er is substantially (several mph) faster with me riding it, despite
    my being less fit - I'll hit, say, 13-14mph where he tops out around
    10mph. Alan can take my 29er up to 15mph.

    The 36er is faster again, with me topping out at a maximum of 17mph (so
    far), despite the wide hub, and long high Q cranks that I've got
    installed.

    The ability to roll over bumps and be stable at high speeds (and have a
    decent stroke length when pedalling) makes the bigger wheels much
    preferable for any distance. However, they are also a bit more
    unwieldy, harder to turn, harder to thread through busy streets, etc.
    The 20" can easily go down to walking pace and thread through
    pedestrians.

    For cross country offroad the bigger wheels will roll over bumps better
    than an equivalently geared smaller wheel (although it is harder to
    build up the necessary momentum due to their probably being harder to
    freemount offroad). If you wanted to do technical stuff you might find
    you need a smaller wheel.

    I find the 36" easily best for road riding, and for XC offroad I'm
    liking it too. A 29er can make a good muni though - I'm going to put
    150mm cranks on it for the purposes of muni, unless I'm doing really
    rough stuff that should roll over most things.


    --
    mark williamson

    Dave: Just a question. What use is a unicyle with no seat? And no
    pedals!
    Mark: To answer a question with a question: What use is a skateboard?
    Dave: Skateboards have wheels.
    Mark: My wheel has a wheel!
    ------------------------------------------------------------------------
    mark williamson's Profile: http://www.unicyclist.com/profile/11301
    View this thread: http://www.unicyclist.com/thread/48929
     
  7. mornish

    mornish Guest

    you could get those cool kooka cranks that i think pdc is selling. that
    would solve your problems.


    --
    mornish

    ><>UNICYCLING FOR MYSLELF TOO<><


    trials_uni wrote:
    > Where did you hear that Bedford unis are not strong? They are the best
    > thing since sliced bread!!

    ------------------------------------------------------------------------
    mornish's Profile: http://www.unicyclist.com/profile/11658
    View this thread: http://www.unicyclist.com/thread/48929
     
  8. mornish wrote:
    > you could get those cool kooka cranks that i think pdc is selling. that
    > would solve your problems.


    it would'nt solve the wheel size issue, we are taking about roll over
    ability here as well.

    the wholy Kooka's are nice but they are alot of cash for a tapered
    crank and my uni's MUni hard..PDC sould get his machinist to broach the
    tapers to a 36 spline pattern for use on KH hubs like Steve Howard has
    done to a few cranks, then we would be in buisness...( of couse the
    price would be around $300 i bet)


    --
    forget_your_life

    dream one dream many....
    *'R.I.P' (http://tinyurl.com/vr86)*
    ------------------------------------------------------------------------
    forget_your_life's Profile: http://www.unicyclist.com/profile/4558
    View this thread: http://www.unicyclist.com/thread/48929
     
Loading...