I was out on my bike yesterday and got to thinking, what is the best wind direction and speed for a time trial? Supposing it’s an out and back course, or just a course that offers the same amount of into and with the wind, is it better to go into the wind first and then have it at your back for the second half, is it best to have some zigzag back and forth? Is a cross angle wind the best, that meaning your never fully with it, but your never fully against it either? Is there an optimal wind speed, enough to help at times, but not so much it overpowers you when going into it or is perfect calm idea? When it comes to hills, is my assumption that it’s best to be with the wind up the hill and into down correct? If this has been answered on another thread, I’d love the link as I couldn’t find it myself.
You have to know how your CdA varies with yaw angle. If you know that you could answer the question using a tool like BestBikeSplit.com
In 7 years of doing TTs I have never found better conditions than calm winds. Even those magic days where you get the wind changing directions and never hitting you in the face have yet to create PR times for me.
Best for a good time, or best wind to beat your competition because you know how to pace better than they do? OR what to your advantage? IF your shorter/smaller… the least wind possible. If your bigger as much as possible.
For a fast time, the wind that starts behind you and gets stronger, or start ahead of you and gets weaker. OR one that starts behind you and turns while you on course and ends up behind you coming back.
I belive direct head and tail winds give faster times than cross winds. OR at least my average speeds in training indicate that.
If I have a 5% reduction in CdA with a 8mph crosswind at 27mph, will they tell me that I’ll go faster than with no wind?
Supposing it’s an out and back course, or just a course that offers the same amount of into and with the wind, is it better to go into the wind first and then have it at your back for the second half, is it best to have some zigzag back and forth? Is a cross angle wind the best
If it is flat and a steady wind on an open course (ie one side not sheltered better than the other), any head/tail wind component will tend to slow you down. Crosswinds will also slow you down unless your drag reduction with yaw is enough to compensate.
If the course is uphill in one direction you can get a benefit if you have a tailwind on that part and a headwind going down. The magnitude of optimal wind will vary depending on how steep the grade is. It is usually a very small benefit vs a windless day.
For me it would be a wind that starts off as a head wind and then changes to another headwind at the turn around. Since I’m smaller than most I do very well against my competition while riding into the wind.
Straight speed and time I would do the best on an out and back with nearly no wind
Equipment issues aside, my guess (and its just a guess) is that if you are lightweight with smaller frontal area but have good watts to kilo and low Cda, anything that puts your heavier competitors at a disadvantage on hills is going to be plus to you. So headwind in the net uphill direction. Then your good Cda will benefit more than them on a net downhill with a tailwind.
Reverse that for heavier riders. They get a boost up the hills and can use their greater absolute watts into a downhill headwind.
my best "40"k was on a day with a 90deg wind ant 10mph(reported weather station)gusting to 20 when folks in parking lot were saying no new PRs would be set that day. wind was 90 deg on the 4 longer legs of the 2 loop course and head on 2 and tail on 2. (2 loopsx4 legs) probably 2miles on short legs and 4 miles on long legs more or less. have not come within 30 or 40 sec of that time before or since. in windier or calmer conditions
How did everyone else do?
How does your power, air density, temperature, equipment, etc compare?
I’ve always had the best luck with a tailwind the whole way.
IMO the best would be a head wind all the way. I have an excellent fit, aero wheels, and a power meter for optimal pacing; this is an advantage over other athletes with same fitness level. Bring on the wind!
IF your shorter/smaller… the least wind possible. If your bigger as much as possible.
Can you explain why this??
They were pretty much the same pace back per distance as usual. so it looked fast for everyone that day. equipment from year to year is very similar. small changes here and there, but nothing that is aero shattering good/bad. power was not particularly good 316w for 29.3mph(surprisingly very similar numbers to last weekend for 30k, but that meter I have a feeling is “off” and just sent into quarq(power dropped 30w 5.5 mi in and stayed there yet speed did not change) and we had double tailwind section(same course as the 40k, but 1.5 laps) cool day, 68deg, humidity 40% pressure 29.97
IF your shorter/smaller… the least wind possible. If your bigger as much as possible.
Can you explain why this??
Just making a generalization than a smaller rider has a better power to weight ratio while a larger rider has a better power to drag ratio and will be less impacted by the wind. Thats making the assumption that the larger rider has a higher cda. Smaller riders get blown around more too.
Probably a bad generalization. Cda is cda and shape means as much as frontal area.
IF your shorter/smaller… the least wind possible. If your bigger as much as possible.
Can you explain why this??
Just making a generalization than a smaller rider has a better power to weight ratio while a larger rider has a better power to drag ratio and will be less impacted by the wind. Thats making the assumption that the larger rider has a higher cda. Smaller riders get blown around more too.
Probably a bad generalization. Cda is cda and shape means as much as frontal area.
More wind tends to increase the time gaps between faster and slower TT riders.