Cervelo: P3 vs P2K

I moved all my components over from the P2K frame to the P3 frame and did another round of Chung testing.  I'm not surprised at the results - the frames are identical except for the seat tube and seat stay shapes.

My average of three Chung test days on the P2K was CdA=0.231.  My CdA on the P3 was measured today at 0.232 in perfect, calm conditions - very clean data.  At least I'm finding the method consistent; and apparently I did a good job of getting my setup the same on the P3 as on the P2K (most drag is the result of body position).

Any changes from here on out will be with body position.

Chasing Neo

I did an FTP test today on the Cervelo - first of the season - and it hurt. I have a very aggressive position (CdA 0.217). My FTP on the TT bike was 96% of what I recently tested on my Tarmac, but my pacing was terrible (the first 5 minutes was 108% of road bike FTP - my PT head unit was in my back pocket and I couldn't see it). My threshold heartrate - last 20 min ave - was exactly the same as on my Tarmac, 162 bpm, so I know I was going just as hard (it hit 168 during my too-fast first 5 min, though).

But that was 'bout what I expected. Good pacing today might have yielded 98% of road bike FTP. I want 99% road bike FTP and CdA=0.210 by February. A new tri-spoke or deep rim front wheel with 20mm tubular running at 160 psi will probably lower my Crr to maybe 0.0045 also.

I'm going to keep my head unit out of sight so I can learn proper pacing based on perceived exertion. I won't have the PT to help me pace when I mount my Zipp disc aero daddy for the Tundra in Feb. But I think I will mount a Polar CS200 on the stem so I can use HR to prevent overcooking the start.

You'd better add an extra interval tomorrow Neo; I'm coming after you.

TTT Pacing

Below are some interesting charts related to TTT pacing. Two very similar teams (only one rider different on a 4-man squad) did the same course (at least up till mile 17.5) under very similar conditions about two months apart - both in competition. The first time we went out much too hard and had trouble at the end. The second time we might have gone out too easy - it's hard to say for sure. On the second attempt (August), we were lagging behind the first attempt (June) pace until very late in the race, when we easily caught and 'passed' ourselves.

The course was more difficult in the second half, which makes the interpretation a little more complicated.



More consistent speed in August:




Making up major time toward the end (10-20 seconds per mile):


Course was tougher in 2nd half, but not too much speed was lost in August:

Alex

If TT stuff interests you, then you'll probably enjoy this blog post by Alex Simmons. It describes his coaching of Jayson Austin, a masters athlete, for the Australian 1-hour record. Bradley McGee holds the Australian record, but Jayson established the 2nd best distance with 10% less power than our man Chad Davies can hold for an hour. Chad, maybe there is a record attempt in your future if you can turn your self into a human bullet and afford a front Zipp disc?

http://alex-cycle.blogspot.com/2009/05/another-hour-of-power.html

Alex was a strong time trialist when he hit a newly installed and unmarked bar-gate on his regular training route a couple of years ago. He lost his leg due to the crash but has battled back to ride again.

Too Aero - No Powero

I think I've overshot my optimization point. I've continued to lower the bars on my Cervelo over the past two years to get more aero. It's a process that takes time because your body has to adapt to the new position every time you change it.

I know the last change improved aerodynamics, because I proved that in coast-down testing last month. But my TT results have been sub-par lately. My road power has not suffered -- if anything, it's higher than a year ago. I suspect my TT problems are due to a loss of power related to my more aggressive position and more acute hip angle. I have the tools to test on the computrainer in various TT positions to check the theory, but it's tedious, painful, and 'trainer season' is over for me. So I think I'll start by flipping my 10-degree Thomson stem to the 'up' position to raise my bars a couple of centimeters and see what happens.

I've been playing around with this stuff for a couple of years using trial and error and my 'poor man's wind tunnel.' I have definitely made progress, but I think it's time to visit the low-speed wind tunnel with Nathan O'Neill in North Carolina this winter to take my positioning to the next level.

Ouch.

Since 2000/2001 my winter training plan has included at least one day per week on the TT bike. This winter is no different. In November and December I've done one SST workout per week on the Cervelo.

Winter is also the time to do position tweaks. A few days ago I added a new Thomson stem to my P2K. It is the same length as my old stem, but has a 10-degree downward angle (the old one had a zero angle). That lowered the front end 16 millimeters [90cm x sin(10 deg) = 16mm]. I also moved the tri-bar extensions forward about 15 mm. To maintain a similar reach, I shifted my saddle forward about 1.5 cm forward. Shifting the saddle forward meant that I had to raise it a little to keep the same height from the BB. I had to add new shifter cables and cable housing due to the extended new position. To polish it all off, I sawed 2.5 cm off the top of my fork, steerer tube, whatever you call that thing, and took off several spacers.

As I mentioned, up 'till now I've only done SST workouts - 85% to 90% of FTP.

After I made the adjustments, I did a 45 minute workout including 4 threshold power intervals - 100% of FTP - each 7 minutes long. Not what I would call a difficult workout.

For two days after the workout I have been extremely sore. Legs, back, shoulders - it's been hard to sleep, even. I don't know if it was the slightly different position, the slightly higher intensity, the fact that it's my first winter over 40, or maybe all three. But it hurts like hell.

The experience has changed the way I'll approach my TT training for the rest of the winter. After a few more workouts to hopefully 'stop the hurt,' I'll start doing shorter, harder intervals on the TT bike. If many of my TT efforts this year will be prologues or very short TTs in the Georgia Cup series, I'd better get used to VO2max level efforts on the Cervelo. So from here out, it's weekly 355s on the TT bike: 3x5min@L5 (L5 is 110% FTP power).

If I find that there is as much difference between the 355s and the FTP efforts on the Cervelo as I found between SST and FTP, then there's probably more soreness in my future.

Five Pain Portraits

I've recently administered FTP tests for a few other riders - 45 minutes - as hard as you can go and still finish the test. All of them were strong and experienced racers. But as you can see from the charts below, none of them had the same approach to the test. It was fun, and sometimes very painful, to watch.

This guy started too easy and probably had too much left at the end:

This guy started too hard and struggled at the finish:

This guy's approach took him to all sorts of highs and lows. A premature finishing push and subsequent burnout probably cost him a few watts:

This guy had good, if slightly undulating, pacing and turned himself inside out, in and out of the saddle, to maintain his number in the closing minutes:

This guy's metronomic output was juuuuusst right (guess who's the experiened time trial specialist of the group?). Amazing consistency and near-perfect pacing.

I expect higher numbers from the first three riders if they choose to test again later in the season - from better pacing strategy if not also from improved fitness. If the last two want higher numbers, they'd better just "Ride Lots."

FTP Paradigm Shift

Three weeks ago I had a very poor time trial result in Ringgold. I felt mentally with it and well-motivated during the race, but in reflection I realized that I never exhibited the 'symptoms' that I normally do in an all-out TT effort. In a good TT, a couple of strange things normally happen to me:


1-At least once or twice during the effort, I convince myself that I've ramped up the power too hard, totally screwed up my pacing, and honestly question if I'll be able to finish the course. I can remember sorting through false excuses in my mind to explain to my teammates why I didn't show up at the finish line ("I got tired" doesn't sound too hot). It's never happened, and I know it sounds ridiculous, but it's absolutely true. Your mind can play tricks on you in a hard TT.


2 - At least a couple of times during the effort, I involuntarily cuss, shout, talk, or whatever. It's like I've contracted Tourettes Syndrome and have no control of my speech. It's really very strange. I've startled a few volunteers by doing it.


Neither of those things happened in Ringgold. I think that means I didn't leave it all out there. I'm not sure why that happened - end of a long, hard season, I guess. Come to think of it, neither of those things has happened in my TTTs, either. I wonder if that's because I'm not giving it everything or because I have rest intervals?


The day after the Ringgold TT, I did a FTP test on the Computrainer. Near the beginning of the test, my computer monitor went out. It got so fuzzy that I couldn't read the wattage on the screen. I continued working hard and completed the test. I was expecting a good result, but when I downloaded the data I found that my FTP was only 264 watts. I had expected it to be around 280, at least. I was disappointed in the result, but in a way I was relieved. I figured it had been a long year and it was normal for me not to be able to maintain my FTP from January to October, and that's why I performed poorly in Ringgold. It all seemed to fit, and it gave me an easy out. I looked forward to starting a new FTP ramp in November.


But yesterday, November 3rd, I performed another FTP test. This time I had a new monitor and could use the average wattage number as a carrott during the test. Guess what? My FTP is 286 watts!


All of this shifts my training paradigm and convinces me of three things. First, the Ringgold thing was a failure of my mind, not my legs. Second, I have to get an Ergomo BB for my TT bike before February to give me a carrott and maximize my power output. And third, I'm starting my FTP ramp for 2009 about 2 watts higher than the end of my 2008 FTP ramp.


Can I gain 20 watts in 14 weeks this winter like I did last winter? I have no idea. Either I'll have lots of work with no improvement this winter, or I'll move to a 300-watt FTP, 4.6 watts/kg. Most likely it'll be something in between.

Perry-Roubaix TT Analysis

The last post covered the bad and the ugly from Perry, so now I'll allow a little space for the good. I had a good TT in Perry and took 2nd. I've been working hard on my position on the bike, I upgraded some equipment, and I've made it a point to do at least one hard ride per week on the TT bike. It's paid off. I'm faster now in TTs than I was last year. This weekend my average speed was 25.9 mph for about 10 miles.

In July 2007, my coast-down testing showed me having a CdA = 0.265 with an assumed 0.005 Crr (rolling resistance coefficient). Last week, after lots of tinkering with my position, adding a rear disc wheel, and installing Veloflex Record tubular tires, I reduced my assumed Crr to 0.045, which - if all else was equal - should have resulted in a higher CdA measurement. But I found that my CdA had dropped consierably to CdA=0.233.

To put that in perspective, a drop in CdA from 0.265 to 0.233 would result in a savings of 56 seconds on a pan-flat 10-mile TT course holding a constant 300 watts.

Using a very rough approximation of the segment lengths and slopes encountered in Perry this weekend, I modeled my ride with known CdA, distance, and time to calculate wattage. I normally put out more wattage while climbing, so that was considered for each segment. The model shows that my average power was about 299 watts. If I'm putting out about the same wattage now on my TT bike as on my road bike, and if my 60-min power is about 95% of my 20-min power, then that relates to a FTP of 299 x 0.95 = 284 watts, which is exactly what I recently tested it to be.

Here's a snapshot of the model. You can find the spreadsheet at Badger 3 if you'd like to use it.

TT Trunk Angle

Copied from http://biketechreview.com/performance/pareto.htm:

"Getting the trunk angle lower can have a significant impact on aerodynamics and performance as summarized in the “rule of thumb” table below (values generated using a mathematical model which uses an average power constraint to determine the optimal pacing strategy for a given TT course):

Table 1. Cherry Creek TT performance and how it is affected by trunk

This is how trunk angle is defined.


It looks like I'll need some new bars (and maybe some yoga lessons) to get to 8 percent trunk angle or better:

I know it doesn't look like it in the photo, but this position actually feels very agressive on the bike. It feels like I'm way out over the front wheel. The ninja-dude's position must feel like he's sitting on the front wheel.

The time listed with each angle is the time saved on a 40K TT IF POWER IS CONSTANT. That's a big IF with extremely aero positions.

Winter L4 work on TT bike - yes or no?

I'm of the opinion that alternating from road bike to TT bike for my weekly 45-min power test is a good way to improve my power on the TT bike for spring. And even if my power is slightly lower in TT position, I think I still get great benefit from a physiological perspective.

A few contributors to Google Wattage and a friend of mine have very different opinions. They say that I'm wasting my time by riding the TT bike in December when I should be using every valuable minute of L4 winter training to increase road bike FTP. They say I should be on my road bike for every L4 workout until February.

I think I'm going to be stubborn and continue to do every other week in TT position because I think the benefits outweigh the costs. If you have an opinion, enter it into the poll on the upper right corner of the blog.

Time Trial Pacing

I've always read how important it is to pace properly in TTs. My last two FTP tests on the Cervelo are hard evidence of that fact.

Two weeks ago, I started out too hard. My first 5 minutes I averaged almost 300 watts. I ended up averaging 251 watts over 45 minutes and was completely exhausted at the end - I didn't even have a good finishing kick.

Last night I started out correctly. My first 5 minutes I averaged 263 watts. I ended up averaging 265 watts over 45 minutes. I felt better throughout the test and had a very strong finishing 5 minute push.

My motivation was pretty low last night, so I attribute the entire wattage increase to proper pacing.

Orbea FTP Test

Last Tuesday was a 45-min FTP test on the Cervelo in TT position on the computrainer -- average 251 watts.

This Tuesday was a 45-min FTP test on the Orbea in road position on the computrainer -- average 274 watts.

That's a 9% difference and realistically probably 10% becasue I was fresher for the TT ride. That's about the difference that I expected between the two bikes/positions. The Orbea ride was also paced much better and I felt much more powerful throughout the test. It wouldn't surprise me if my TT ride wattage next Tuesday is higher due to better pacing alone.

The unexpected part of the whole deal was finding out that my computrainer wattage is 10% higher than the wattage measured by my Ergomo (mounted on my Orbea). I'm confident that my Ergomo is accurate, and this confirms a 10% difference between the two that I found last week when testing a teammate. I thought maybe his left leg was weaker due to a prior injury (which would result in an Ergomo/CT discrepancy), but I guess not. You'd expect the computrainer number to be a little less than the Ergomo number (maybe 2-4%) because of drivetrain losses between the crank and the road, but not 10% different.

All of my Tuesday night FTP tests will be on the computrainer but not always with the Ergomo, so I'll use CT numbers in my winter-training tracking charts. Measuring change is the important part, not measuring accurate wattage. Plus using the CT numbers will make me look stronger than I actually am, which is always a bonus!

Bottom line: My road FTP is about 265 now. Hopefully when I test in early January it will be at least 280.

Breaking the Hour Barrier with Geometry

When I modified my TT bike setup a couple of months ago, I pushed the saddle back and lowered the bars a little. It was more aero, but it bothered my back and I didn't feel any more powerful (I thought I would with the saddle further back.)

Here's my July position with angles depicted:


Notice the 87-degree hip angle. That's too acute according to TT position experts - and I could tell that it was too acute becasue my back hurt after a hard 90-minute effort and I didn't feel powerful.

My latest position feels super. I'm as powerful as on my road bike and I'm lower and more aero than I was in the previous setup. Even though I lowered my bars about 4 cm to achieve the second setup, moving the saddle forward about 6cm actually opened up my hip angle and allowed me to breathe better. The 90-degree hip angle and the closer-to-90 shoulder angle also both feel more powerful.



I won't mess with my position much more, because this one works. This summer's position changes have lowered my 40K TT time from 1:04:30 to about 59 minutes, even though my road bike Functional Threshold Power has barely changed. That kind of improvement is worth the effort.

TT improvement

My experiment with a new TT position has to be considered a success. I feel just as powerful as before and I'm much more aero. I will do a final tweak this week by lowering my bars another cm and bringing my seat about 1-2 cm further forward, then I think I'll leave it alone. It's difficult to see my improvements without a power meter on the Cervelo, but I know they are there based on my recent rides.

Three times in the past 5 weeks I've done the Thursday Worlds course in Macon with the group ride:


Chasing or being chased helps tremendously with the motivation factor, which is critical for an hour and a half TT ride at full power. The first two times I averaged 21.9 and 22.1 mph. I skipped a week and last night averaged 23.2 mph. That's a huge improvement. Some of it is due to a shortened course the third time that did not include Moran Road, which has a long false flat. But I know it was not all due to the course change, because I was averaging about a mile per hour faster at the Montpellier Rd turn this week compared to the other two weeks.

Also very importantly, my back was not sore this time. The rearward saddle and low bars position I tried before put too much strain on it. The new position is much more comfortable. I could have ridden for another hour at the same pace, I think, if I'd had food. Long TT skills don't really help me in Cat4, though, because our TTs are usually only 10 to 25 miles long.

I've ordered a replacement for my slow Tufos (Vittoria Chrono EVO CS tubulars - hopefully with at Crr 0.0004), but they won't arrive in time to be mounted and dry properly for the State TT in Rome in about 10 days, so Tufos and a Crr of about 0.006 it is. I didn't need that 30 seconds anyway.

TT Position - Phase II

Aero is important for going faster - that's obvious. But cycling past age 40 would be nice, too, and I'm 39. My new aero position is undoubtedly more aero than my old position, and therefore it's faster; but it puts more strain on my lower back than my old TT position did (and much more than my road position does) because my legs-torso angle is more acute. The last thing in the world I need is a bad back - that'll shut you down fast and for a long time. So I'm going to change again to save my back.

The reason my torso angle is so acute is that I lowered the bars and slid my saddle back at the same time when I developed my new position. I lowered the bars to flatten my back and drop my frontal area - that's standard. But I figured my power output would be higher if I slid my saddle back to something similar to my road position. I think it works - my power seems good. And moving the saddle back gave me an important unexpected benefit: it increased my reach so that my upper arms are at about a 45 degree angle with vertical. That lowers my shoulders and upper body more.

So I need to increase my legs-torso angle without going back to the higher shoulders-torso position. The first obvious thing to try is to slide the saddle back forward - maybe not as far as it used to be, but several inches, at least. That'll raise my shoulders because my upper arm angle will get back close to vertical. To lower my shoulders back down, I guess I'll take spacers out and lower the bars again.

One thing that I have learned in messing with this stuff is how cool Levi and Floyd's positions are on their TT bikes. I mentioned that I changed my upper arm angle away from vertical and lowered my shoulders by stretching out more. They have taken the exact opposite approach and changed their upper arm angles by bringing their bars in closer to the saddle, giving them the 'mantis' look. I'd love to try that, but I'd need a smaller TT bike frame - probably not going to happen. Before I move my position again, I'll photograph it and compare it to my old one so I can see how the angles are changing.

New TT position

I have worked very hard over the last 5 weeks to improve my time trial position to lower my CdA (drag coefficient x frontal area). On July 4th I performed aero testing showing my CdA to be 0.297 with my skinsuit, TT helmet, shoe covers, and the body position that I've been using for the last 6 years. That body position was set in a bike fit when I purchased the bike at All3Sports about 6 years ago.

I have made three significant changes gradually over the past 5 weeks, one at a time between rides. The first was a lowering of my bars by moving spacers from beneath the stem to above the stem. I've only lowered the bars about 2 cm so far and could probably go at least one more cm over the next month or so, but I only drop 1/2 cm at a time for acclimation purposes.

The second change has been a narrowing of my elbows by bringing the elbow pads on my bars closer together by about 2 cm.

The third change (the one that's made the most difference) has been seat position. I knew that my triathlon seat position was set a lot more forward than my road bike position. Triathletes need to save their hamstrings for the run, and the forward position also opens the waist angle to allow better breathing. I found that my road bike saddle was about 12 cm further back from the bottom bracket than my tri bike. That's a lot more than I expected. I flipped the seat mount around backwards on my Cervelo and also pushed the saddle back on the rails to move my saddle back about 8-10 cm from it's original position.

The original reason I did that was to get a similar saddle-to-pedal relationship to my road bike so that I'd use those muscles similarly and not have to train additional muscles for the TT bike. That's still a good reason, but I've discovered an even bigger benefit: by shifting my hips back 8-10cm, the angle of my upper arms relative to horizontal has moved from about 90 degrees (which maximizes my shoulder height above the bars) to an angle that might be about 65 or 70 degrees to the horizontal. That has had the effect of lowering my shoulders even further relative to my hips.

It does reduce the angle of my torso to my legs, but so far it seems manageable - I'll know more after riding that way for a while and doing some power testing on the computrainer.

The end result is a reduction of my CdA from 0.297 on July 4 to 0.270 on August 13th). At first those are just numbers on the page, but when I calculated the effect of that improvement on TT times for various distances, I was quite surprised.

IF I can hold a similar power in the new TT position as I held in the old one (a big if), I can expect to save about 45 seconds on a 10-mile TT like Perry-Roubaix (and most GA Cup races) and I can expect to save over 12 minutes on the Rock-n-Rollman half-iron 56-mile course. It seems almost ridiculous, but that's what the math shows. No wonder Levi gets himself into that crazy position for TTs - there are huge benefits to being so aero.

In the best-case scenario, I can get the aero improvement and generate more power due to the more road-bike similar position. I'm going to stop moving my position now and work for a few months on getting powerful and comfortable with the new setup.

My next task is to address rolling resistance. Based on published data, I can save chunks of time by ditching the tubular Tufos on aero wheels I'm now using (maybe Crr=.006) and replacing them with good aero clincher tires (maybe Zipp 404s) using latex tubes (maybe Crr = .0045). So next I'm onto the flat road coast-down tests for Crr calculation.

TT Frontal Area

In my methodical attempt to improve my time trialing, I plan to do coast-down aero testing to try changes in body position, etc. But before I start doing coast-downs over and over I need to nail down as many known variables as possible to make sure I'm not wasting my time and getting junk numbers (although the testing is a great way to get in good hill repeat sessions).

One of the variables is frontal area. Most folks just combine frontal area (A) with drag coefficient (Cd), call it CdA and are done with it. But if I have a good measurement of A, then I can isolate Cd pretty accurately. Then when I make positional changes on the bike, I can get a preliminary idea of how much it will help just by measureing A again.

To measure A, I took a digital photograph, imported it into AutoCAD, properly scaled it using the tape measure in the picture, traced my frontal area, and measured it directly. I found it to be 4.185 square feet, or 0.3888 square meters. I was pleased to know it was fairly close to the 0.35 square meter estimate I had been using. Based on the limited coast-down testing I did the other day, I think my current CdA is about 0.297. That's good news, becasue that's not a great number. For my size, I should realistically be able to lower it to something between 0.230 and 0.265 depending on whose research you read. Conservatively, that would be at least 89% of my current drag.

Power required to overcome drag is directly related to CdA, so a 89% improvement in CdA would mean I could go the same speed at 89% of the power output it used to take. That type of improvement would be well worth the effort. It might not show benefits at first, though, because a more aggressive position might limit my power output to 89% of my old position until I can train enough in a new position to get the power back up. Six months of once a week time trial training should do the trick, I hope.

Here's the photo with my frontal area hatched in AutoCAD:










Andrew Coggan believes the optimal position on a TT bike for aerodynamics and power output is having your shoulder 5cm above your hip. I don't know if I measured properly, but as you can see in this photo, my shoulder is at least 18cm above my hip in my current position:

Poor man's wind tunnel

I wanted to know what effect my TT bike, Aero helmet, and skinsuit had on my drag coefficients and TT finish times, but didn't want to pay $2500 for a couple of hours in a wind tunnel. So I found the longest fairly low-traffic hill near my house, a 0.6-mile climb with a 3.5% average grade. Starting at a constant 20mph at the top to eliminate momentum factors, I coasted down the hill lots of times with different aero setups to determine my drag coefficients. I know that my power was 0 watts, so I was able to eliminate power measurement from the list of uncertainties. My typical average speed was in the 23mph range, so I know my numbers will be valid for my average TT speeds.

The only factor pushing me down the hill was gravity, so weight was important. I carefully weighed myself in my kit/shoes/helmet and the bikes prior to testing.

I ran at least 3 'no-car' runs for each setup and averaged them. (I found that each car that passed me during the tests cut about 1 second from my finish time, so I threw out all the runs where cars passed me during the test). There was little or no breeze, it was 88 degrees, and I alternated test runs with various equipment in case the environmental conditions changed during the testing.

The spreadsheet I used required entry of a drag coefficient and/or a bike and rider frontal area and factored those with an air density number to get an 'A2' factor that it used in the calculation. I got everything to work well in the spreadsheet, but I still don't know exactly what my frontal area and drag coefficient are, but I'll work on that later. I used a rolling resistance of 0.004 (which I realize now might be too low for my tubular tires - it's probably nearer .0055).

Here are my averaged results for each setup:
Orbea Orca with standard team kit and helmet, riding in drops - 1:34.5
Cervelo P2K with standard team kit and standard helmet, in aerobars - 1:30.0
Cervelo P2K with standard team kit and TT helmet, in aerobars - 1:29.3
Cervelo P2K with skinsuit and TT helmet, in aerobars - 1:25.8

I was pleased to find that even my low-tech testing was able to accurately measure the effect of even changing helmets on a minute and a half section. The repeatability of the runs was very good, usually within 1 second.

The biggest surprise was the skinsuit. Changing from the team kit to the skinsuit has as much effect at going from the road bike to the tri bike! And the numbers are huge. For a 40K TT, the skinsuit would save 1 minute, 46 seconds. That's a lot of time. Based on my time in the recent half iron man, I saved 4 minutes and 18 seconds purely by wearing the skinsuit and TT helmet. For the short 10-12 mile TTs usually included in the Georgia Cup races, I'll save almost a minute by wearing the skinsuit -- that's amazing to me.

And these numbers are not wild guesses, they are real world measurements that can be easily and accurately extrapolated to racing.

Don't stop training hard -- the bike won't power itself. But for God's sake, buy a skin suit if you're going to ride TTs.

Next I plan to play around with my bar height, bar angle, etc. to see if I can get any measurable effect. And rolling resistance is also on the list of things to investigate.

Since originally posting this earlier in the year, I've fine tuned my analysis spreadsheet. You can view or download it at Badger 3 if you are interested.

Faster TT - Attack Hills or Kill Descents?

In discussing time trial strategies with other riders, I've found that everyone seems to have a different approach to dosing their power over a rolling TT course. There's the 'don't start too hard' rule, which I think is very valid -- I make that mistake often. Then there's the question of when to stand out of the bars, etc.

But the question that I was most uncertain about was whether to put more effort into climbing or descending (assuming that your average wattage for the entire ride is constant). A very good time trialist I know says he powers the descents and that gives him an advantage. I've always heard that I should put out more effort on the climbs and recover on the descents. One coach told me to stand on the last 25% of each roller to maintain momentum. So I've done the math.

I modeled the situation using a spreadsheet allowing input of temperature, elevation, power, frontal area, friction coefficient, rolling resistance, and weight for various course sections. I constructed a 1-mile TT course with a 1/2-mile, 6% climb followed by a 1/2-mile 6% descent. I used aero coefficients that represented climbing on the hoods and descending in the drops. The average power over the course is 250 watts for all three situations.

Constant effort:
If I generate a constant 250 watts over the course, I get the following times: climb (2:58)+ descent (0:45)=total (3:43).

Harder climbing:
If I generate 270w for the climb and 178w for the descent, I get: climb (2:48)+ descent (0:46)= total (3:34). That's 9 seconds faster than the constant power ride.

Harder descending:
If I generate 240w for the climb and 290w for the descent, I get: climb (3:05)+ descent (0:44)= total (3:48). That's 5 seconds slower than the constant power ride.

I tried the same thing for a 3% climb and got similar results. The end result is this: If you are going to ride with a non-constant power output, it's better to hit the hills hard and take it easier on the descents. Extra power output doesn't do you as much good when you are at higher speeds because it gets eaten up by wind friction at a 3rd power rate.

Why does my friend the good time trialist think it helps to kill the descents? Probably because he kills the descents but continues to kill the climbs too! So he ends up with a greater average power for the ride. The moral of the story is "If you have to recover somewhere on the ride, do it on the descents, not the climbs."