Finding "correct" wattage for TT

[giannip]

Hi I have a TT coming up during a 3 day, 4 stage race. It's pretty short, 6.7km (4mls), and I'm trying to pinpoint my wattage so that I don't blow. Depending on the wind, the TT SHOULD take 8-9min. Is it wise to find a samples from races and find peak time from them to get an idea or could I aim for a % of FTP? Finally, I'm planning to start the first 30s or so quite conservatively. Is there a % of the target wattage I should be aiming for, or just go by "feel" I.e hard effort but not flat out, then settle into effort. Thanks for your time.

 

[An old Guy]

I am old and don't race but ...

9 minutes. Being old I need a warm up - walk the 30 yards or so to the start. Start out at 110% of my 10 minute sustainable power output. About 4 minutes in my heart rate should be about 60-70% max. Adjust my power so that I hit my max heart rate 30 seconds before the finish - that should be about my 5 minute sustainable power. (I can go the last 30 seconds without the benefit of my heart pumping enough.)

---

But for you. You should know how much warm up you need. You should know how much work you can do in 8-9 minutes. From that should should be able to develop a plan. If you don't have a chance of placing high in the TT or improving your position in the stage race, you might as well take it easy.

No one here can tell you more about you than you can.


Have a good race.

 

[giannip]

Thanks. I do have an idea of the effort I can put out, just wondering if there are other opinions or something I may have missed. P.s. I don't use HR

 

[daveryanwyoming]

Giannip,
I'd estimate both your time and target power from hard training efforts or previous time trials, not cherry picked from races. Even odds the races were a lot more dynamic and if you were riding tactically or tired from previous efforts, you likely didn't lay down your best possible power for 9 to 10 minutes of riding part way through a mass start race. Even if it was a make or break 9 to 10 minute hill it's unlikely you hit it fresh and left it all on that hill which is what you want to do in your upcoming TT.

Have you ever done 10 minute intervals, what's your best average power for that duration. If you average 40kph for your TT you'll finish in a bit less than 10 minutes once you account for the start and or turnaround if it's an out and back.

You could use Monod predictions driven by best efforts at say 3 to 5 minutes and 20 minutes but an actual best effort for 10 minutes would be better.

Realistically this is a short time trial and even though you definitely don't want to blow up out of the gate you'll want to get into pace pretty quickly compared to say a 20K or 40K TT. If you do regular 20 minute training intervals then I'd start this the same way you've started your best 20 minute efforts but after the first three minutes or so you should just ride on feel and try to leave it all out on the road. The biggest thing power pacing helps you with is those first few minutes when neither your RPE nor your HR have had time to respond to the starting effort and it's easy and common to go way too hard and then limp home. Keep it to your normal 20 minute L4 training pace at the very start and once you've gotten past those opening minutes just ride hard to the finish and dig for all you can at the end.

Once caveat, if you're riding in aero bars but you haven't done any hard training intervals in aero bars then perhaps take another 5% or so off of the starting power as most folks lose a little power in the aero bars until they've trained enough to adapt to that position.

Good luck,
-Dave

 

[swampy1970]

4 miles in about 8 or 9 minutes... Someone is planning or getting 53x12 turning over at a fair rate of knots. I think we should be asking you for advice!

 

[lanierb]

I'm with Dave on this one (as usual). Peak 8m power from a race file isn't likely to be high enough. If there's time, try an 8m all out interval in training between now and the race to get an idea what you can do. Go all out. Then aim to start at that wattage in the race and hopefully you can kill it in the last mile or so and beat that.

 

[giannip]

Thanks so much for the detailed replies.

I was going to use a TT from last year as a benchmark. It was 8.3km, so a little longer & time was 10:54 (317w AP and NP)

I was thinking I'd target 320 as the benchmark to keep at and as you said, maybe start putting on the pressure with a few min to go.

I was going to start of around 290-300, which is what I tend to do in my 15. Typically in my 15min the last 10min are the peak power area e.g. start of around 290 and last 10min are around 310-315.

The wind is usually from the back and slightly from the side but interestingly enough my last 2 15min efforts last week, were within 2w, even though the first was with a strong tailwind (av 100rpm) and thee second into the wind (av 80rpm) so from a cadence point of view I should be ok.

Later in the year I did another 6km TT where I think it hit it too hard (and def didn't warm up properly), as the first 4m were around 345 and then a pretty big slow down

I think aiming for 320 & winding it up might be the way to go..

 

[daveryanwyoming]

Originally Posted by giannip .
I think aiming for 320 & winding it up might be the way to go.....

That sounds wise and is based on your own history for similar durations. Just don't wait till the last few minutes to ramp it up if you feel good. Keep a reasonable lid on it for the first three to four minutes but this is too short a time trial to wait till the end. Prologue's and short TTs are hard in part because you can't really just pace for the long haul and outlast folks you've got to ride them pretty aggressively but hold back just enough that you don't blow till the very end.

Good luck, let us know how it goes,
-Dave

 

[giannip]

yep, I'll be ramping it up gradually from min 3 I think. If I could hold 345 for 4 min, I'm hoping to ramp around 330, or where it starts to hurt, and then give it gas the last 2min or so. Last question Any suggestions re length of warmup etc? Was thinking around 30-40 starting with 15min L2, then doing a few 1min L4 efforts, maybe addng a 5min just under threshold & then winding down 10-15min before start.

 

[daveryanwyoming]

Originally Posted by giannip .
...Any suggestions re length of warmup etc?

Was thinking around 30-40 starting with 15min L2, then doing a few 1min L4 efforts, maybe addng a 5min just under threshold & then winding down 10-15min before start.

That's similar to what I do, I'll start in comfortable L2 and just ramp it up into Tempo as the legs loosen up taking about 10 to 15 minutes to ramp up to high Tempo. Then I'll spin for a few minutes easily and then do five minutes at Threshold, spin another easy five and do two minutes at L5, spin down, get off the trainer, take care of any last minute stuff including a rest room stop and then spin out on the road hovering not to far from the start line until I've got five minutes or so till my start. Don't miss your start and do at least a few minutes of road warmup to warm up both tires before your ride. I find the couple of minutes up in L5 to be really useful as an opener for short time trials and a very good reminder of what VO2 Max efforts feel like to help me avoid the classic mistake of starting in L5 only to blow up and finish slow. Lot's of other approaches work, just remember to warm up well for such a short TT as you'll be going fairly hard right from the start.

-Dave

 

[giannip]

Awesome. Thanks again!

 

[swampy1970]

... waiting for the 3 minute mark is a bit too long - that's almost 1/2 way in a 8 minute TT! In 10 mile TT I'd say somewhere around 30 to 45 seconds to get settled in. It's mainly just about avoiding that massive blast off the startline.

Depending on where the TT is placed in the weekend you might want to do a bit more threshold and above in the warm up. If you've had one or two hard road stages prior to the TT then you may need a longer warm up just to freshen the legs a bit. Throw in some easy spinning at the start of the warm up and in between harder intervals. Although it sounds somewhat counter intuative, I personally would increase the length of the threshold part of the warmup as it always takes my legs, when stuffed, longer to at least feel like they're ready for a big effort.

... and if the TT follows a road stage in the morning, don't forget to have a couple of pre-made bottles of recovery drink stashed in a cooler for immediate guzzling as well as some food. Your TT prep would, in that case, start during the prior road stage.

As lanierb said, it'd be worthwhile going out and seeing what you can do for a 5 to 8 minute effort but with the caveat that during the actual TT you might be able to eek out a bit more power due to motivation or you might be a few watts down if you're stuffed from earlier efforts...

 

[An old Guy]

Originally Posted by giannip .

Thanks. I do have an idea of the effort I can put out, just wondering if there are other opinions or something I may have missed.

P.s. I don't use HR

I think you missed the heart rate monitor.

I think you missed the fact that this is 4 races over 3 days.

I think you missed the importance of using several tools rather than one.

 

[giannip]

Hi old Guy Thanks for your opinion. I haven't used a hr since 2007 & no, I didn't miss it. In the context of this very short TT, how will the HR monitor help me in the first minutes of the effort ??? Looking at the bigger picture, if I'm tired, under the weather etc etc I can not complete my workouts & I FEEL there is something wrong. No, I did NOT miss the fact that it's 4 stages in 3 days. I signed up for the race remember ? I DO use various tools. I.e a power metre & RPE. You might have missed the point that there are different ways to achieve the same result. This is mine.

 

[daveryanwyoming]

Originally Posted by swampy1970 .

... waiting for the 3 minute mark is a bit too long - that's almost 1/2 way in a 8 minute TT! In 10 mile TT I'd say somewhere around 30 to 45 seconds to get settled in. It's mainly just about avoiding that massive blast off the startline....

Gotta disagree with you here Swampy. I've reviewed an awful lot of power files from TTs and the most classic mistake is hitting not just the opening minute but the opening five minutes way too hard and ending up with a low AP and slow speed as a result. In a longer TT I'd pace the first five to six minutes below FTP and then build but in something as short as Giannip is riding he shouldn't wait that long.

Remember he blew up last year holding 345 for the first 4 minutes of a 6km TT. He's planning to roll out at 320 for the opening minutes and build from there. That's already pretty aggressive based on previous results but likely necessary for an event this short. The bottom line is that RPE can't catch up in 30 to 45 seconds and this isn't a kilo where everybody pedals squares around the final turns and hope to hang on to the finish. He'll likely be on course for nearly ten minutes(he'd need to sustain 50+ kph including start and turnaround to finish this in 8 minutes) which is too long to just gut it out on desire after an overly hard start.

-Dave

 

[swampy1970]

You don't see pursuiters waiting for the 3 minute mark... and for most of us 4km is going to be way on the wrong end of 4 minutes or 5 and change which makes it a classic VO2 max interval. 5 minutes... 8, 9 minutes... very similar barrel of fish. With the 8 minute effort you'd get a little longer to aim before you pull the trigger and shoot.

That's why you go out and test, test and test some more. I thought part of the idea of fun "toys" like powermeters is having the ability of knowing what is very likely to work when it comes to racing. 95% of the maybe's, what if's, should I's and I think's should be taken care of way ahead of time leaving the 5% of the rest of your gotchas - like getting into an aero tuck when your back and rump are roadrashed to hell and back or the two days of hotel food suddenly want out when you least expect it or how to time trial when dehydrated and overheated despite drinking more fluid than a fish, a la Lance 2003.

RPE - not valid because it'd all be pegged at 10 (or 20 depending on what scale you're on) when you get to the finish anyway and if prior stages are hard then it could be a RPE of 10 just to get to 300 watts and "feeling" is so overrated In a well paced time trial RPE just means Really Painful Experience for the latter half of the event anyway. There is no scale unless you tack on a Spinal Tapesque "this one goes to 11..."

... of course, we don't know what the course is like. It could be tailwind and downhill or there could be lots of corners and a finish up the something like Muur de Huy in the Fleche or the time trialists nightmare - long straight road, slightly uphill and a bloc headwind.

 

[An old Guy]

Originally Posted by daveryanwyoming .

He's planning to roll out at 320 for the opening minutes and build from there. He'll likely be on course for nearly ten minutes(he'd need to sustain 50+ kph including start and turnaround to finish this in 8 minutes) which is too long to just gut it out on desire after an overly hard start.

I don't know what tools you use, but according to my spread sheet 320w is 31.5mph. When I was young, from time to time I could handle that. Even at the end of a long ride without rest days. If he is being honest about his abilities, he could do it.

But I don't think he is going to do much in the TT. He is asking too many questions. He has too many answers.

I don't like to say this, but most guys claim to ride a couple classes above their skill/power levels.

 

[daveryanwyoming]

Originally Posted by An old Guy . I don't know what tools you use, but according to my spread sheet 320w is 31.5mph. ..

Any tool that predicts speed from power without knowing a thing about the rider's: weight, size, position, equipment or without some way to estimate CdA including wheels, frame and helmet or Crr and without knowing anything about the altitude or air density he's racing is isn't worth using.

But from experience at 70kg and 5'10" on a full TT bike with deep front, disc in rear, aero helmet, skinsuit and booties with a field tested CdA in the vicinity of .235 m^2 and tires with a Crr of .005 on decent asphalt roads 320 watts doesn't get me anywhere near 30 mph without a stout tailwind on flat roads. Add the energy to start and turn around and neither 320 nor 340 is likely to get me through a 6.7km time trial in 8 minutes.

Try calculator over at: http://www.analyticcycling.com/ForcesPower_Page.html

Assuming he's lighter, and more aero than I am at 70 kg(total bike plus rider plus kit) and a CdA of .220 he'd still need 427 watts to hold 31.5 mph at sea level and that doesn't take into account the cost of accelerating at the start or turnaround.

Based on those same assumptions 320 watts yields a steady state speed of 12.7 m/s or 45.7 kph (28.3 mph) very fast for sure but even with those fairly generous assumptions and no time allowed for the start or turn around he's still looking at roughly 9 minutes not 8. Realistically anything sub 10 is probably a really fast ride for someone with that power but not a lot of TT experience and likely not a lot of time spent optimizing his aerodynamics or pacing.

I've known Giannip for several years and take his power numbers at face value. I expect he's seen those numbers more than once, whether he'll see them on race day in the aero bars is always another question but that's why we race instead of just sending power files in to the officials.

-Dave

 

[tonyzackery]

^^Dave Ryan droppin' some knowledge...goes without saying for most around this forum, but those new around here need to recognize...

Anyway, 320w ain't gettin' this unit anywhere near 50kph (31mph). Try about 40k (25mph) for this 6'2" parachute...

 

[swampy1970]

If we keep this thread going for another day or two maybe we could achieve the highest number of assumptions ever in a TT thread. Maybe Giannip is as aero at Dr Coggan, unlikely.... but it's possible, in which case 300 watts would be plenty for 29mph... After all "word" has it that the good Doc produced less than that for that average over 40km. Then again Andy's ride was at a few thousand feet and if that was the case for the OP then his FTP maybe effected (training altitude vs race altitude) I'm still of the belief that Andy has his own personal time machine and discombobulator that confuses timing officials We could throw in another variable - passing traffic. Given we don't know the course we can't rule this one out either. Dave, you had me second guessing my thoughts on "the grace period" to settle into the effort at the start, so I had to check The Book. ~2 minutes for a 10mile TT and almost none for a 4km pursuit seems to be the recommendation. 8,9 or 10 minutes - grey area... I'm still sticking with about a minute. Giannip - what is the course like? Do you know or is that an unknown? ... But maybe we're over thinking this. All we really need to know is when does this TT occur is relation to the other stages and if it's not the first stage then how many watts can you hold with similar effort in your legs when you're on the bike you're riding in the TT - in full aero tuck, in skinsuit and aero lid. That latter item may be an issue if it gets toasty.