Proper TT Pacing on a rolling course

[ghutchinson]

Question to forum:

Assuming you use a powermeter (ie. pt) during a tt. Also, assume you have done a dozen or so 40k tt's, all very close to 275w, average pace, therefore we will say that is your threshold.

During a rolling course TT, what intensity should this person try to hold during the tt, specifically during the up hill and down hill sections, in order to have the fastest time?

One theory is to hammer on the uphills and recover on the downhills. The other theory (mine) is to hold the threshold on the uphills and downhills. Therefore, hold 275w during the uphill and downhill sections and on the flat sections. In reality, it is really hard to keep the watts low up the hills and very hard to keep the watts up during the downhills.

Any input??

 

[velomanct]

for me when i am doing a TT, if i go above my predicted average power of say 275watts, its only going to hurt me. once you go considerably above LT in a long TT, it is going to take twice as much time below LT to return to normal state. here is an example.
im riding at 275w on a flat section, then i hit a hill and ride at 325w for a minute. it is going to take me 2 or 3 minutes at 225w to return to my level of precieved exertion of normal TT pace(275w). so in the end, my average power has dropped even though my average effort felt the same. also, if you ride above LT for a few minutes, it's going to weaken your legs, slowing you down.
so, in conclusion, i feel it is best to keep the watts as close to the predicted average(275 in this example). if you hit a downhill that is more than -3% grade, you can allow your watts to drop to say 250. or even 200 if it is a steep grade. if it is a grade of more than -8%, then you might as well just spin your legs to get rid of the lactic acid. pushing 200 watts on a -8% grade barely increases your speed over 0watts. also, never stand on the pedals and get in an aero tuck where all your weight is on the pedals. if you don't keep your legs moving lactic acid wont be removed as quickly and could make your legs worse, because they are flexed. the best technique on a steep downhill in a TT is to stay seated while spinning your legs without any resistence(as long as you dont have any corners, duh)this is were you can use expotenial wind resistence to your benifit against other riders, or the clock. it will help freshen up your legs, with very little drop in speed. the payoff(fresher legs) will be more valuable than the 2 secs you lost on that minute long downhill. the body likes consistency, that's where it is most efficient.
great time trialers are the riders who are experts at pacing themselves to a T.

 

[J-Law]

Originally posted by velomanct
for me when i am doing a TT, if i go above my predicted average power of say 275watts, its only going to hurt me. once you go considerably above LT in a long TT, it is going to take twice as much time below LT to return to normal state. here is an example.
im riding at 275w on a flat section, then i hit a hill and ride at 325w for a minute. it is going to take me 2 or 3 minutes at 225w to return to my level of precieved exertion of normal TT pace(275w). so in the end, my average power has dropped even though my average effort felt the same. also, if you ride above LT for a few minutes, it's going to weaken your legs, slowing you down.
so, in conclusion, i feel it is best to keep the watts as close to the predicted average(275 in this example). if you hit a downhill that is more than -3% grade, you can allow your watts to drop to say 250. or even 200 if it is a steep grade. if it is a grade of more than -8%, then you might as well just spin your legs to get rid of the lactic acid. pushing 200 watts on a -8% grade barely increases your speed over 0watts. also, never stand on the pedals and get in an aero tuck where all your weight is on the pedals. if you don't keep your legs moving lactic acid wont be removed as quickly and could make your legs worse, because they are flexed. the best technique on a steep downhill in a TT is to stay seated while spinning your legs without any resistence(as long as you dont have any corners, duh)this is were you can use expotenial wind resistence to your benifit against other riders, or the clock. it will help freshen up your legs, with very little drop in speed. the payoff(fresher legs) will be more valuable than the 2 secs you lost on that minute long downhill. the body likes consistency, that's where it is most efficient.


great time trialers are the riders who are experts at pacing themselves to a T.

On a flat TT your example of going above LT and recovering below LT for a more extended period is true and will cost you time. On a hilly course I have seen the calculations that show it is not true. Because of gravity you gain more seconds by going above LT and then spending extra time recovering on the downhill. Obviously there is a point of diminishing returns but I don't know where that is. You wouldn't want to go 600 watts uphill and then take forever to recover on the downhill.

 

[velomanct]

Originally posted by J-Law
On a flat TT your example of going above LT and recovering below LT for a more extended period is true and will cost you time. On a hilly course I have seen the calculations that show it is not true. Because of gravity you gain more seconds by going above LT and then spending extra time recovering on the downhill. Obviously there is a point of diminishing returns but I don't know where that is. You wouldn't want to go 600 watts uphill and then take forever to recover on the downhill.

you're right on.

 

[acoggan]

Originally posted by J-Law
On a flat TT your example of going above LT and recovering below LT for a more extended period is true and will cost you time. On a hilly course I have seen the calculations that show it is not true. Because of gravity you gain more seconds by going above LT and then spending extra time recovering on the downhill. Obviously there is a point of diminishing returns but I don't know where that is.

For me, the point of diminishing returns seems to correspond to a power that would elicit approx. 100% of my VO2max - which is as you might expect based on physiological principles.

 

[ghutchinson]

Thanks for the replies.

Is there some general rules of thumb out there, assuming I don't know my power output at VO2max?

For example, based on your predicted avg. wattage for a 40k TT, if the hill is >1min. than keep your wattage below 120% of your predicted avg. W. If the hill is <1min. than keep your wattage below 140% of your predicted avg. W.

I found velomancts reply discussing downhill grades very useful. I also liked the 2:1 reference on the concept of taking the power output above LT and having to recover for about twice as long as the time spent above LT. all good stuff.