back to the issue of the wind tunnel, the topic behind what was a promising thread only yesterday...
obviously the wind tunnel has utility, as it's been used successfully in so many ways, especially for car makers and aviation. and i'm not in any way even close to being an authority on this subject. but i think part of the problem is that bikes are much, much more complicated aerodynamically than aluminum tubes with wings, what with exposed edges, and wheels inside of fork blades and hidden (or not) behind seat tubes, and riders oscillating on the saddle and churning legs, cranks and spokes.
my concern stems from applying the test of reasonableness to what i see coming out of both the wind tunnel and when applying math to problems of weight, rolling resistence, and wind drag, basically all the forces that impede one's forward progress.
one popular formula has a pound of weight making so little of a difference that if you were to strap 100 pounds to the bike you'd only go 1:40 slower in a 25-mile time trial. and the people who believe in their math model actually believe this extrapolation to be true.
then there are some of the formulas that have been developed from wind tunnel data, such as the one where you lose 15 seconds when you take a drink from your down tube water bottle. when i take a drink out of my down tube bottle i don't suddenly find i'm 200 yards behind the guy i was riding with.
i believe i've seen pretty robust claims on behalf of the new oval fork. but kraig, didn't you test it and find it to be about the same as the other forks out there, which were all fairly close to each other? (except i don't think you tested cervelo's wolf, did you?). so who are you going to believe?
and finally, there seems to be issues of protocol. i've seen cases where tests performed within the past year or two differ from tests performed 5 or 10 years ago, and the variance is chalked up to a difference in protocol or interpretation. this begs the question, what confidence can we put in today's protocol and interpretation, especially with so few follow-up studies being done by other aerodynamicists?
all this represents a problem, and i find that some of you resort to a "throwing up of your hands" and resting instead on anecdotes. if chris lieto rides a round tubed bike then this is incontrovertable proof that aero tubes are bunk. either that or its proof that chris lieto is an idiot. take your pick. if bjorn andersson can ride a fast bike split off his slow cadence and laid back position, here's proof that such a position and cadence is the best for him and perhaps others.
lance rides a much faster cadence now, during 4 tour wins, than he did in his previous iteration. back then, six of seven years ago, would we have said that 20 extra pounds and a slower cadence were good things, because back then lance was a world champion and a tour stage winner and the extra weight and less cadence obviously therefore worked in his favor?
there are reasonable alternatives to confusion. i rather like the idea of the velodrome. in this case you'd be testing entire systems, and so it would be hard to know for sure why one bike was better than another. but i like to think that if you had a pair of bikes set up more or less the same, and you had a rider alternate 5km on each bike, for 30km in total, using the same wheels throughout, you might find something out.
here's my guess: that you might find a surprise or two, but in general you'd find out that the things that seems reasonable to you now would prove themselves out. i suspect you'd find that aero tubes are faster. but not a lot faster. and that weight does make a difference. as do disc wheels. but not so much that they can't be overcome by the application of a lot of force, which is why strong riders ride well regardless of equipment.
maybe an extra 20 pounds of tire pressure is worth 30sec over 40km, and aero tubes are worth 10sec, and a cut-out is worth 15sec, etc. this is not enough to cause lieto to fall off the back, because he's so strong. are each of these products worth enough in time savings for you to buy them? you decide.
but i seem to remember some of you really obsessing on whether a wetsuit would save you 2 or 3 seconds in transition while getting it off. so, again, i would just think that if you applied the test of reasonableness to the problem many of these questions can be brought down to size.
Dan Empfield
aka Slowman
obviously the wind tunnel has utility, as it's been used successfully in so many ways, especially for car makers and aviation. and i'm not in any way even close to being an authority on this subject. but i think part of the problem is that bikes are much, much more complicated aerodynamically than aluminum tubes with wings, what with exposed edges, and wheels inside of fork blades and hidden (or not) behind seat tubes, and riders oscillating on the saddle and churning legs, cranks and spokes.
my concern stems from applying the test of reasonableness to what i see coming out of both the wind tunnel and when applying math to problems of weight, rolling resistence, and wind drag, basically all the forces that impede one's forward progress.
one popular formula has a pound of weight making so little of a difference that if you were to strap 100 pounds to the bike you'd only go 1:40 slower in a 25-mile time trial. and the people who believe in their math model actually believe this extrapolation to be true.
then there are some of the formulas that have been developed from wind tunnel data, such as the one where you lose 15 seconds when you take a drink from your down tube water bottle. when i take a drink out of my down tube bottle i don't suddenly find i'm 200 yards behind the guy i was riding with.
i believe i've seen pretty robust claims on behalf of the new oval fork. but kraig, didn't you test it and find it to be about the same as the other forks out there, which were all fairly close to each other? (except i don't think you tested cervelo's wolf, did you?). so who are you going to believe?
and finally, there seems to be issues of protocol. i've seen cases where tests performed within the past year or two differ from tests performed 5 or 10 years ago, and the variance is chalked up to a difference in protocol or interpretation. this begs the question, what confidence can we put in today's protocol and interpretation, especially with so few follow-up studies being done by other aerodynamicists?
all this represents a problem, and i find that some of you resort to a "throwing up of your hands" and resting instead on anecdotes. if chris lieto rides a round tubed bike then this is incontrovertable proof that aero tubes are bunk. either that or its proof that chris lieto is an idiot. take your pick. if bjorn andersson can ride a fast bike split off his slow cadence and laid back position, here's proof that such a position and cadence is the best for him and perhaps others.
lance rides a much faster cadence now, during 4 tour wins, than he did in his previous iteration. back then, six of seven years ago, would we have said that 20 extra pounds and a slower cadence were good things, because back then lance was a world champion and a tour stage winner and the extra weight and less cadence obviously therefore worked in his favor?
there are reasonable alternatives to confusion. i rather like the idea of the velodrome. in this case you'd be testing entire systems, and so it would be hard to know for sure why one bike was better than another. but i like to think that if you had a pair of bikes set up more or less the same, and you had a rider alternate 5km on each bike, for 30km in total, using the same wheels throughout, you might find something out.
here's my guess: that you might find a surprise or two, but in general you'd find out that the things that seems reasonable to you now would prove themselves out. i suspect you'd find that aero tubes are faster. but not a lot faster. and that weight does make a difference. as do disc wheels. but not so much that they can't be overcome by the application of a lot of force, which is why strong riders ride well regardless of equipment.
maybe an extra 20 pounds of tire pressure is worth 30sec over 40km, and aero tubes are worth 10sec, and a cut-out is worth 15sec, etc. this is not enough to cause lieto to fall off the back, because he's so strong. are each of these products worth enough in time savings for you to buy them? you decide.
but i seem to remember some of you really obsessing on whether a wetsuit would save you 2 or 3 seconds in transition while getting it off. so, again, i would just think that if you applied the test of reasonableness to the problem many of these questions can be brought down to size.
Dan Empfield
aka Slowman