What is the Optimal Team Timetrial Strategy?
If you are riding in a team online or IRL how do you pick a team? How do you decide who rides first? How do you decide how long to pull for? and at what watts?
All these questions can be answered from nothing more than the rider’s FTP. That is because you can build a pretty good mathematical model of team strategy which will actually tell you how fast your current roster is compared with every other possible combination.
Today I will try and describe how this works. And its best to do this by starting at the back. Let’s use an example of 4 riders doing a 2hr team timetrial.
In terms of order I assume we can take for granted that the strongest rider always starts on the front? Why? because once they get tired they are the first to recover in the pack and then the first to re-pull at the front. You want to put most demands on the strongest riders.
Step 1: Watts to Avoid Being Dropped
The first step is to work out how fast the slowest rider can go whilst in the draft. It’s easier to just use “effective watts” rather than time, so we want to know how many effective watts (ie the watts you would need to go that speed if you were on the front) the weakest rider.
This is actually a little tricky, but if you use their predicted power curve (from https://fft.tips/curve) to show that a typical FTP240 rider can sustain about 216w over two hours so the team cannot go at pace that exceeds an average of 216w for any rider 100% sheltering in the pack
Next you need to adjust for the draft effect. You can get this from https://fft.tips/draft or direct from Burt Blocken here:
This is aerodynamic drag not drivetrain or CRR drag so it is not precisely talking about raw watts and its dependent on team size (and wheel distance) but to keep it simple we can say you save roughly 150% raw watts in the pack vs same speed on the front. For our example this means that the team cannot go at pace that exceeds an average of 324w for person #4 even if they don’t pull at front.
Step 2: Initial Pull at the front
The next step is to work out how long each person can pull at 324w on the front? We can find this using trial and error from fft.tips/curve but the time-to-exhaustion calculator will tell use precisely. It is the same as the time you can spend in ERG mode with the turbo-trainer set to 324w.
For rider #1 the answer is 31m
For rider #2 the answer is 20m
For rider #3 the answer is 10m
OK, so now we know that the three stronger riders can pull for 31m+20m+10m before needing to recover in the pack (or maybe give up!). So this team as assembled could almost certainly ride 61m whilst pulling@324w using the front 3 men. But we want a time of 2hrs/120m. So we need to add some team rotation which will help recharge rider’s energy
Step 3: Pull Rotation Schedule
If we keep the same ratio of time at the front to 31:20:10:0 (or 3:2:1:0) then we can work backwards from 120m. We would need 60m from rider 1; 40m from rider 2 and 20m from rider 3. There are various ways to work out number of rotations but remember each rotation is an interval workout, with a near max effort and then a (slight) recovery. In general the more you divide the same amount of work into more intervals then the easier it gets eg
1×60 is harder than
2×30 which is harder than
3×20 which is harder than
But pulls of less than 1–2mins reduce efficiency of the team because it takes a minute of so for the speed to stabilize and each time a rider drops back they are riding solo (alongside the team) and have to catch on the back….which is hazardous! For these reasons, in this case let’s peg the minimum pull at 2mins for rider #3. Therefore (if all riders take same number of turns):
Rider #3 needs to do 10x pulls@ 2mins @324w
Rider #2 needs to do 10x pulls@ 4mins @324w
Rider #1 needs to do 10x pulls@ 6mins @324w
Step 4: Rotation Difficulty vs Recovery
We know rider #3 can ride flat out at threshold for 10m@324w but can they ride twice this 10x2mins@324w? The good thing, is that using this schedule they would get 4m+6m in the pack after each pull, ie 10m “recovery” probably at z3 or “tempo”.
You can calculate the answer using W’ (prime) but I already made a calculator for this called the FFT intervals calculator (https://fft.tips/difficulty) and this handy calc says 321w would be more realistic than 324w. What about the other riders?
Rider #3 can likely do 10x pulls@ 2mins @321w
Rider #2 can likely do 10x pulls@ 4mins @307w
Rider #1 can likely do 10x pulls@ 6mins @309w
So all riders would have to throttle back their pulls accordingly, which is also good for rider #4 who would be a threshold the whole way otherwise! Indeed they reduce to 206w (310/1.5) which they can maintain for 137mins.
Step 5: Average Effective Watts
Now we come to the overall effect. For this we simply have to average the watts of every riders contribution (at the front) in order to find the team’s effective watts……..as follows:
309×6 + 307×4 + 321×2 = 3724/(6+4+2)
Sure, CDA and CRR would normally come in here but we can make average assumptions and that works out at 310w or 41.3kph on a flat course. Notice how as a team, the mean FTP is 270w for 60mins but actually the effective team watts is 310w over 120m! Not bad! This is mainly because the pull at the front is higher for everyone than there watts in the pack.
Step 6: A more rigorous gold standard
I have kept things simple in this example, and my quick manual calculation above gives a ballpark figure but I have coded this more accurately in google sheets using a few more tricks and failsafes. Let’s check this “gold standard” against today’s result……..
I said above 310w and 41.3kph; but the calculator tells me that the true answer is 323w and 42.1kph and that’s because with the watts of the team so close person #4 should not have been been excluded at the start……at least not unless their FTP is below 237w (when they would be a problem). However this shorthand was not far off the right answer!
So now you know:
The optimal TTT strategy depends on riders ability and team composition/roster
Outlliers (fast and slow) cause issues, that must be adjusted for immediately to avoid drops
The front rider should always throttle their speed back for the slowest man in the draft but this is hard to do on the fly
Riders should basically pull until their power drops below the ability of the next man to pull (ie not as long as possible).
As this is a super tricky calculation, our new calculator should give you the optimal strategy in any team event / track pursuit / team timetrial / zwift TTT etc.