Wheel info

Discussion in 'Cycling Equipment' started by [email protected], Jan 28, 2009.

  1. Peter@vecchios

    [email protected] New Member

    Joined:
    Dec 30, 2007
    Messages:
    2,111
    Likes Received:
    4
    Tags:


  2. ScienceIsCool

    ScienceIsCool New Member

    Joined:
    Jun 25, 2006
    Messages:
    333
    Likes Received:
    0
    Hmmm. Actually, it would be neat to plot out measured power versus velocity for the ride profiles he's made and curve-fit to find out the different values of drag in his model. You could also come up with a good estimate of measurement error which would tell you a bit about whether any differences in setup would be lost in the noise, so to speak.

    John Swanson
    www.bikephysics.com
     
  3. ibi-m

    ibi-m New Member

    Joined:
    Apr 2, 2008
    Messages:
    18
    Likes Received:
    0
    Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into 60% rider drag, 8% wheel drag, 8% frame drag, 12% rolling resistance .5% wheel inertia forces and 8% bike/rider inertia


    comments on this one? is this accepted by the community?
    thanks

    equation of motion is absolutely correct, but it all depends on what you put in it.. I came across this one long ago, almost forgot about it... it would be great to see the curves for different velocities for comparison.. then again, this is free data, so we can't complain much.
    les roues artisanales has plenty of wheels related info, some killing the myths about total wheel traction resistance...

    http://www.rouesartisanales.com/article-15441821.html
     
  4. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,611
    Likes Received:
    140
  5. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,611
    Likes Received:
    140
     
  6. Phill P

    Phill P New Member

    Joined:
    Jul 9, 2006
    Messages:
    513
    Likes Received:
    0
    I'm surprised that frame aero is equal to wheel aero.
     
  7. parawolf

    parawolf New Member

    Joined:
    Jan 16, 2006
    Messages:
    865
    Likes Received:
    0
    I've heard - no reference available - that lowering your head by 2cm is the same aero gain as a set of fast wheels.

    Don't shoot the messenger on that one... but given that the cyclist drag is so high, it has potential.
     
  8. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,611
    Likes Received:
    140
    I'm not sure about 2cm, but on this German Tour Mag test (which I've posted a zillion times before :p), the rider cut 59w of drag, moving from the hoods to the drops, but only cut 15w going from 32-spoke wheels to 2 tri-spokes




    They first put Uwe Peschel on a 'normal' road bike

    Required output to sustain 45km/h.

    Stevens San Remo bike with hands on hoods: 465 Watts
    Same bike, hands down on the drops: 406 watts
    Same bike, Easton Aeroforce aero bars: 369 Watts
    Same bike Triathlon position (5.5 cm lower bar, saddle forwards): 360 Watts
    Same as above, with 2 carbon Tri-spoke wheels: 345 Watts

    Cervelo Tri bike + Tri spoke wheels: 328w
    Cervelo Tri bike + Tri spoke front + disk rear wheel : 320 w
    Same as above with Giro aero helmet: 317w
    Same as above with speed suit: 307w


    Spekken la Doiych? :)
    http://www.dk-content.de/tour/pdf-archiv/tests/zeitfahren_material_0107.pdf

    Another one:

    http://www.cervelo.com/reviews/aerotest.pdf
     
  9. Phill P

    Phill P New Member

    Joined:
    Jul 9, 2006
    Messages:
    513
    Likes Received:
    0
    What about with a low rider recumbent?
     
  10. ibi-m

    ibi-m New Member

    Joined:
    Apr 2, 2008
    Messages:
    18
    Likes Received:
    0
    Same bike, hands down on the drops: 406 watts
    Same bike, Easton Aeroforce aero bars:
    369 Watts

    very interesting - 10% less only because of different bars? care to elaborate, thanks
     
  11. Bro Deal

    Bro Deal New Member

    Joined:
    Jun 26, 2006
    Messages:
    6,698
    Likes Received:
    2
    The recumbent takes off 98 Watts.

    Unfortunately the required beard adds 105.
     
  12. 531Aussie

    531Aussie Well-Known Member

    Joined:
    Apr 11, 2004
    Messages:
    12,611
    Likes Received:
    140
    that's going from normal bars to aero bars
     
  13. Phill P

    Phill P New Member

    Joined:
    Jul 9, 2006
    Messages:
    513
    Likes Received:
    0
    So hot today the power keeps cutting out at work because too many AC units running across Melbourne. Train lines are buckling due to over expansion and half the trains aren't running.
    3 days in a row of 43degC+, cold change tomorrow....only going to be 35 and 30 over the weekend.
     
  14. Bob Ross

    Bob Ross New Member

    Joined:
    Jun 22, 2006
    Messages:
    363
    Likes Received:
    4
    I've cited it before, but I still get a kick out of that quote from the guy on the MIT cycling team, who, after evaluating wind tunnel data, pointed out that an aero helmet offers vastly improved performance gains over aero wheels: "So you could spend $2000 on wheels, or $200 on a helmet and be faster."
     
  15. parawolf

    parawolf New Member

    Joined:
    Jan 16, 2006
    Messages:
    865
    Likes Received:
    0
    Hence why i've recently bought myself an aero lid... and own aero wheels...

    Aero lids are only allowed on TT's and on the relevant track events so they get extremely limited use in Australia. A set of 404 or 808's (or similar from Edge, HED, etc) would get more race time by a factor of 10:1).
     
  16. dhk2

    dhk2 Active Member

    Joined:
    Aug 8, 2006
    Messages:
    2,214
    Likes Received:
    39
    15W by switching wheels is a substantial savings, but remember that's at 45 kph (28mph). Because aero drag power is a function of the cube of the speed, at a more typical pace, say 20 mph, the savings would only be be 36% of 15W, or ~5.4 watts.

    Same factor applies to aero helmets, aero bars and all the rest. That's the reason this stuff makes sense for a fast TTer, not so much for a group ride at 20 mph or less.
     
Loading...
Loading...