Comparing my two bikes

Discussion in 'Road Cycling' started by quilkin, May 29, 2013.

  1. quilkin

    quilkin New Member

    Joined:
    May 29, 2013
    Messages:
    3
    Likes Received:
    0
    I have a Ti Litespeed road frame which is about 9 years old now, and also an Al Specialized Transition TT setup, about 5 years old. Both are well-maintained. Recently I started using Strava for comparing rides and this has shown some something odd; the Specialized seems faster even when climbing and when not using the aero bar position.
    To test this, I have over the last week or so done four test rides, two on each of 2 different days. Each ride is 10 miles and involves 190m of climbing. For the first day's testing, I rode the Specialized first, waited 5-10 minutes then did the same ride with the Litespeed. For the second set of tests I did the same but in the other order, to try to eliminate differences due to tiredness and/or not being 'warmed up' enough.
    The bikes are set up the same; I have measured all the standard distances (saddle / crank, saddle to bars, height of bars, etc) and they are all identical to within 1 cm. The two machines weight the same to within 200g.
    On all tests, the Specialized is on average 4% faster than the Litespeed. Up the main hill (a climb of nearly 100m) it is about 10% faster!
    Remember for these tests I'm not using the aero bars at all. I would certainly expect the Specialized to be faster on a flat TT course and using the aero bars, but what could cause this difference I am seeing on a hilly course with identical riding positions? Could the Litespeed frame be faulty in some way? I've done probably 20k miles on it. That extra 4% could be all I need to stay keeping up with others on my club rides, which I am finding more difficult these days.... Thanks for any suggestions!
     
    Tags:


  2. alienator

    alienator Well-Known Member

    Joined:
    Jun 10, 2004
    Messages:
    12,596
    Likes Received:
    160
    It's difficult to say anything about your results because such tests are rife with "noise", in the case "noise" being the influence of unconstrained variables, things like wind, varying power output, and etc. Did you use a power meter? Using a power meter is about the only way to insure that your output is the same and that you aren't unknowingly putting out more power on one bike than the other. Did you use the same model and size of tires inflated to the same pressure? When you say the fit between the two is basically the same, what do you mean? To be the same the fit should be measured from a standard that doesn't change with geometry, one like the bottom bracket. All else being equal, it would be expected that the transition, a more aero bike, would be a faster bike at a given power output. How much faster is the question.
     
  3. quilkin

    quilkin New Member

    Joined:
    May 29, 2013
    Messages:
    3
    Likes Received:
    0
    Thanks for your thoughts. I agree a power meter would be a more scientific way of comparison, but they're pricey! I 've tried to reduce the effect of wind by doing comparisons within 40 minutes of each other on each set of tests, and anyway the difference is more marked on climbs where wind has less effect. The Transition frame is marginally more aero, yes, but again this would affect the faster/downhill sections of the ride more, but this is not what I am seeing.
    I have re-measured all distances from the bottom bracket and they are pretty much identical. The wheels and tyres are different, but very similar designs and weight and at the same pressure; I have tried swapping these on earlier tests but that seemed to make no difference (if anything, the wheels on the Litespeed should be faster because they cost more!).
     
  4. alienator

    alienator Well-Known Member

    Joined:
    Jun 10, 2004
    Messages:
    12,596
    Likes Received:
    160
    Aero concerns are still the dominating factor on climbs, at least up until the climbs start to get steep. I wouldn't expect the Transition to do as well on downhills, at least if the downhills involve turns since Tri bikes aren't known for their great handling. It's difficult to say with any certainty why you are seeing the results you are seeing. It could be the result of the Transition being a little bit stiffer, but that's difficult to prove as there's been no study correlating bike stiffness with performance. Assuming the difference in weight is in the Transition's favor, that will provide a small benefit, emphasis on the small, as in a few hundredths of a mile an hour. When it comes down to it, whatever the reasons, ride what feels best to you for a given ride.
     
  5. alfeng

    alfeng Well-Known Member

    Joined:
    Jul 23, 2005
    Messages:
    6,723
    Likes Received:
    126
    FWIW. Almost the same isn't the same ...

    Consequently, I think that you definitely need to redo the test AFTER swapping the wheels ...

    • the hubs, or their adjustment, can definitely make a difference ...

    FYI. At one point, I made a concerted effort to ensure that my "test" bike had THE SAME level of components as my supposedly better bikes so that the results of trying anything new would be discernible ... subjective, to be sure, but a knowable-and-known "baseline" ...

    • different shifters could have an impact on your results if you are shifting more with one bike than with another, BTW.

    In other words, if you really want to compare frames, then probably need to move ALL the components over from one frame to the other ...

    And then, you will know if the presumably more flexible Titanium frame is an energy vampire or if other factors are the reason for the difference in your observed times.
     
Loading...
Loading...