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Virtual Time Trial

  • 22-01-2009 11:41am
    #1
    victorcarrera
    Registered Users, Registered Users 2 Posts: 1,059 ✭✭✭


    Anybody done this? What Km/h improvement to expect by changing from carbon road bike (8 Kilos) to carbon time trial bike with all the go faster bits & aero helmet and skin suit, over flat non technical course.
    I understand there are many variables here but I just want an estimate similar to when I change from 12 Kilo Aluminium road frame to 8 Kilo carbon road frame I get a 3Kph improvement over the same 40Km distance.
    Please indicate whether proven or estimated.


Comments

  • #2
    scottreynolds
    Closed Accounts Posts: 2,001 ✭✭✭scottreynolds


    Pure maths but it makes sense........

    http://www.kreuzotter.de/english/espeed.htm

    The theory is that when riding a tri bike you frontal area (think wall against the wind) is smaller and therefore there's less resistance. There's another post here about tri bars I think (search for that) but essentially it says that the biggest adv to be gained was the adding of tri bars.


  • #3
    blorg
    Registered Users, Registered Users 2 Posts: 15,995 ✭✭✭✭blorg


    There was an interesting article recently in Bike Radar that went into this in some detail.
    They also found that outdoors there was a 60-70 watt saving at 40km/h between the normal road bike setup, which required ~280-290W at this speed, and the full time trial setup (~220W). That worked out at between 22-24% in aerodynamic savings. To put it another way, it was 9 seconds per kilometre, 2'14 per 10 miles (16.1km), 5'33 per 40km, and 24'58 over 180.2km, the distance of the bike leg in an Ironman triathlon. Or another way, if you can ride a road bike at 40km/h and switch to a time trial bike and helmet, you can do over 44km/h.

    To be honest I would be a bit surprised if you are getting +3Kph over a flat course simply by swapping a 12 kilo road bike for a 8 kilo one, I would not have expected such a major difference at all.


  • #4
    victorcarrera
    Registered Users, Registered Users 2 Posts: 1,059 ✭✭✭victorcarrera


    Thanks for really interesting links guys, especially speed and power calculator which seems to concur with blorgs suggestion re bike weight. Im going to play around with this a little more. My own TT results may be inaccurate due to using two different bike computers (didnt think about that until now), and well, flat course irish style. Ive no way of calculating this. Might just try stopwatch in future tests. Thanks for your interest.


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