More on Chung Testing

It's been impossible to do much testing in the past two months due to weather.  I can't get out there in a skinsuit if the temp is below 55 degrees - it's just too uncomfortable.  And any breeze at all invalidates the data; so that eliminates lots of days.

But yesterday I was able to get another set of data collected on my P2K.  So now I have three data sets with the same setup.  My CdA results from three different days on the same test course are 0.228, 0.230, and 0.235.  Based on n=3, my average CdA is 0.231 and the standard deviation is 0.0036.  These numbers reflect skinsuit, TT helmet, shoe covers, no gloves, Zipp 303 front wheel, and power tap with Kinlin XR-300 (30mm) rear wheel.

My Cervelo P2K frame was slightly damaged in a crash last year, so I'm about to move my P2K components over to a Cervelo P3 frame a teammate recently gave me.  I'll set it up exactly the same as my P2K, except I'll run a Zipp 404 on the front instead of a Zipp 303.  The only difference between the new test setup and race setup will be the absence of my disc wheel during testing.

These aren't my bikes, but depict my old P2K frame and new P3 frame:

I'll be interested to see how much difference the frame change and 303 vs 404 change make to my CdA.

Lyle and I are a Little Different

I've always wobbled in the saddle.  Always.  I've been riding a bike for 25 years and I've always been told that I need to lower my saddle or do this or do that to correct my wobble.

Well I have tried.  Many times.  To no avail.  I studied the issue quite a bit a couple of years ago.  You can read about my ponderings in my 2006 posts: Saddle Height and at Saddle Height/Q-Rings.

A friend graciously reopened that conversation for me the other day.  This time I thought about it some more and decided to check LLD - leg length discrepancy.  I carefully measured my trochanter heights - the height from the floor to the tip of the little bony protrusion on your hip bone.  It's the most lateral protrusion of the greater trochanter in this image:

One trochanter is 35” from the floor. The other is 34.25” from the floor. Hmmmm.  It seems that in LLD speak that's about a mile.

I did some Google work and found lots of people rushing to their doctors and trashing all thier shoes because they had a leg length discrepancy of ¼” or ½”.

I seem to have a ¾” LLD goin’ on.

I’m leaning towards the “If it ain’t broke, don’t fix it approach; but we’ll see.  I'd like to fix the wobble; and I think the LLD is the likely cause.  But I suspect there's a good chance I'd screw something else up if I started adding shims, et cetera.  And all that would be a pain in the arse, even if only figuratively.

And I haven't had any pain or discomfort, just an occasional snickering teammate.  I can live with that.  Lyle and I don't want to be like the rest of you anyway.

Force Reps

Base HR Distribution

My heart rate distribution for the past 28 days:

Power distribution for the same period:

The next few weeks will see an increase in Temop and Threshold percentage.

Force Reps

I was just looking at data from a force reps session (each interval is 18-20 pedal strokes at max pedal force in the 53-12). My wattage is typically a consistent 600 watts for the efforts. But the thing that caught my attention was the torque.

WKO+ tells me that my peak crank torque (actually it's virtual crank torque, which is calculated from PT rear hub wattage and cadence) at the max efforts is about 1160 lb-inches. If you divide that by the length of my cranks, 172.5 mm (6.89 inches), you get 168 pounds (1160 lb-in divided by 6.89 inches).

My max squat is just a little more than that. I don't really know my max squat weight, because I never do (and don't plan to ever do) 1-rep max squats. But based on the rep chart in "The Cyclist's Training Bible" I think it's about 190 lbs, which would be about 1.3 time my body weight, which is fairly typical.

The thing that has me a bit confused is that I'd assume most of the pedal force is coming from the down-stroke. If that's the case, I'd only be able to put out a little more than half of my max squat force when pedaling (if you assume the upstroke has maybe 20% of the max downstroke force, it'd be 70% max squat force, or 0.7 x 190 = 133 lbs right?).

I need to think on this one for a while. Feel free to enlighten me in the comments section if I've missed something or messed up the calculations. Am I putting out more force than I think with my upstroke? Am I putting out more than I think with my downstroke due to momentum and body weight factors?

Decoupling Test

Either Friel's decoupling theory* is bogus, or I'm definately ready for the transition to more intense work.

The results of my 2-hour decoupling test at high L2 today: -2.88% decoupling. Yes, that's a negative sign. I guess maybe I warmed up and became more efficient as the ride went on?

*Friel's decoupling theory: if heartrate to power ratio increases (drifts) more than 5% over a long ride, then you need more aerobic development prior to moving out of the base periods and on to more intense training.

Winter Weights and Cycling

Every year this time (base period/off season for most cyclists in North America), there begins a flurry of on-line discussion and argument about the benefits and risks of strength training for cyclists. It's not hard to find well-known coaches and physiologists to argue either side of the issue. Coggan thinks weights are useless and that the fatigue generated by strength workouts can be harmful to endurance athletes because time is taken away from productive training; Friel has always (at least since the '80s) been a proponent of strength training in the base training periods.


I have a lot of respect for some of the folks on Google Wattage (where many of the heated discussions occur) who dismiss the use of weights and/or strength training because “the research does not show that it helps; therefore it’s a waste of time so it hurts.” Research and real scientific results are crucial to learning how to use your training time most efficiently. It’s perilous to ignore the results of multiple legitimate scientific studies. But I think the anti-weights voices are a little too stubborn in their narrow, but very consistent, response: “the research does not show that weights make you faster.”

Maybe they don’t make you faster. But I can tell you from n=1 that they make you feel faster. That’s worth something. They make you feel more confident. That’s worth something. They might make your bones healthier and more dense. That’s worth something. They make you less prone to injury. That’s worth something. They make you look and feel better. That’s worth something. They make winter training less monotonous. That's worth something. And a whole big bunch of very successful cyclists and coaches have reached the conclusion, for a variety of reasons, that weights are worth the time. That’s worth something.

For me, all those minor ‘somethings’ add up to a lot. So I’m sticking with the weights for a few decades until the researchers get it sorted out.

L2 Rides and November Centuries

This is a good post by Joe Friel explaining some benefits of the long L2 ride. There is no doubt that significant ride time at L3 and L4 are both important for aerobic system development in the winter/base period of the year. But there are things L2 can give you that L3 and L4 don't.

The Aerobic Base Ride

On a related note, I found this statement by Hunter Allen yesterday on Google Wattage; it sums up my thoughts on doing century-length rides in November and December:

"One other point is that longer rides made up of the components above (L1, L2, and L3) can help you make the next quantum leap in FTP. I have seen so many Masters riders that are restricted to 8-12 hours a week and no matter how hard and smart they train, just never are able to get to 'the next level'. Only when they can introduce a 2-3x a month long ride into their training plan that tax both the cardiovascular and muscular endurance components are they able to make the quantum leap. It doesn't mean that every weekend has to be a 100+ mile ride, but 2-3 a month can make a difference even if you never, ever race near that distance or to that level of fatigue."

I understand the 'only train as long as your longest race' philosophy. I just don't agree with it.

Walthall Oil Kits

2010 Walthall Oil Cycling kits. Thanks to a great group of sponsors and to Kristy for help with design.

Quadrant Analysis

Here's a quadrant analysis chart of two very different efforts. The one in green is a force rep workout (20-sec of hard low-cadence interval with spinning in between). The one in purple is the 2008 Elberton Crit. All the points above the red line represent segments of effort above my threshold power.

I'm not sure what to do with the information yet, but it's interesting to look at. The most obvious use would be to compare race efforts to training efforts to see if my training is properly race-specific.

PT Calibration Curve

It's raining, I'm in a rest week, and I needed a break from house chores and work; so instead of a ride today I did a full range of Power Tap static calibration tests, as suggested by Dr. Chung.

I found that my PT is pretty accurate. It appears to read an average of about 2.3% low overall, which is within the advertised range, I think.

The errors are slightly larger than that (up to 4-5%) when I'm in my 25-tooth cog or in my 12-tooth cog (climbing or sprinting, just when I'd like to see big numbers the most!). The errors are slightly lower than that (0-2%) when I'm in my middle cogs (16-19 tooth range). It makes sense that the PT strain gauges might have more trouble measuring torque when it's applied to the very ends of the measuring cylinder (hub body).

Errors that small won't make bit of difference to riders when using their PTs for training. But I can use the information when Chung testing to get more accurate results. I'll just keep the chain on the 17 cog and scale my power numbers back by about 1.5% before doing the calcs.

And I'll run a few tests every 3 months or so to give me confidence that my PM calibration isn't drifting.

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.

Power Tap Static Torque Test

I performed a static torque test on my Power Tap at lunch today.

I took three weights:

1 - a 45 lb olympic plate (which actually weighed in at 45.5 lbs)
2 - two 45 lb olympic plates (90.5 lbs)
3 - my body weight

I ran three tests. The instructions say to use 50-lbs or more, which might explain why the first test at 45.5 lbs was off a little. In the first two tests, I hung the weights from the right pedal when it was parallel with the floor and the rear brake was locked. In the third test, I balanced myself in a door jamb such that all my weight was on the right pedal and the front brake was locked. (hanging 90 lbs from the pedal of your bike is more difficult than you might imagine).

It turns out that my PT is DOBA (dead on balls accurate) at the two higher weights. That makes me feel better about my recent testing. Now I need to do the same thing with my teammate's PT to see if I can eliminate a source of potential error with his results.

My results:

Test 1: expected 69.96 in-lbs, measured 63.0 in-lbs (thought maybe I was in trouble here)
Test 2: expected 138.39 in-lbs, measured 139 in-lbs (DOBA)
Test 3: expected 239.86 in-lbs, measured 240 in-lbs (double-DOBA)

Here are instructions for performing the Power Tap static torque test (I swiped them from a wattage Q&A posted by Dr. Coggan):

Technically, the PowerTap cannot be user-calibrated, but its accuracy can be checked using a simple test that is similar to the SRM
calibration check. First, check that the transmission icon is on, and if not, give the rear wheel a spin. Then, enter the torque
mode by holding the “Select” button down for 2 seconds or longer (the “WATTS” designation will disappear from the top line.) Apply
the rear brake sufficiently to lock up the rear wheel. Now, measure torque as follows: with the cranks exactly horizontal (right
crank at 3 o’clock), hang a known weight of at least 50 lbs from the right crank, or simply stand on it – hence the name ‘stomp test’!
Measured torque = (weight in lbs) × (crank length in mm) × (1 in/25.4 mm) × (cog teeth/chainring teeth).
For a 159 lb rider standing on a 175 mm crank, with the chain on the 39 tooth ring and the 23 tooth cog, 159 lbs × 175 mm ×
1 in/25.4 mm × 23/39 = 646 in-lbs. Compare this to the displayed value by calculating % error as
(measured torque - displayed torque)/measured torque.

So if you find your strain gagues are not calibrated properly, there's nothing you can do but send it to Saris for recalibration, I guess. You can rezero the thing yourself (actually most PTs are set up to re-zero themselves while you are coasting), but you can't modify the strain gauge settings yourself.

Ok, Grasshoppa - time to rush home and hang weights on your cranks to see what's up.

Stumped

My last post presented my nice neat Chung results. Everything turned out exactly as expected once I measured my test hill and input the real numbers.

But now I have a problem. A teammate tested with me on the same hill at the same time. He used a power tap just like me, he weighed in and weighed out after each test segment just like me. The weather conditions were the same. The course was the same.

But when I processed his numbers, the only way I could get the virtual hill to be the right height was to use an unrealistically large Crr, 0.007. That yeilded an unrealistically low CdA for him - 0.190 m^2 (he's 6'3" and about 180 lbs - I don't think he has a CdA under 0.2).

So I looked at all the inputs. Most were identical to my tests as mentioned above. Same spreadsheet, too.

I looked at weight: he tested using two different bikes, so his weight was actually about 2 pounds different between runs, but the two runs still yeilded exactly the same Crr. That tells me the weights were right (and we used the same scale).

What about distance/speed? We both calibrated our Power Taps using a three-revolution weighted rollout, averaging three rollouts, before the test. And I checked the distance measurement of the hill versus both of our data sets and everything matches there. So I don't think the problem is distance/velocity.

That leaves the Power Tap power measurement as the only other source of error I can think of. I thought I had a culprit. To obtain a data set that would give me a Crr for him on my hill near the expected 0.005, I was required to lower all of his power numbers to 95% of their measured values. That got the hill height right, but his CdA would still be around 0.210 on his TT bike and around 0.260 on his road bike. I don't believe his Power Tap is wrong AND he has an unrealistically low CdAs. I'm stumped - but only temporarily - I'll figure it out.

My next steps - let him do runs using my Power Tap and put him on my calibrated Computrainer to see if the Power Taps read the same. Then we'll go from there.

Chung TT Bike Results

This plot shows the results of my recent Chung Method aerodynamics testing with my Cervelo P2K. I wore full aero gear (skinsuit, TT helmet, shoe covers, aero front wheel), but used my standard Powertap wheel on the rear.

Because there is very little air resistance on an 8% climb at 150 watts, I was able to accurately discern my Crr using the climb side of the virtual profile. Then with a little iteration, the descent side of the profile, where CdA greatly overwhelms Crr as a force against the bike at 43 mph, allowed me to determine my CdA. I found it to be very close to the CdA result I got about a year ago when I did extensive coast-down testing on a 1/2-mile 3% descent. I found it to be 0.232 then, and this week's testing shows0.230. That's a pretty good number, but I'm not a big guy (5'9" and 146 lbs) and I ride in a very aggressive position, so it's not completely unexpected.

The first set of runs is with the setup I used for most of this season. For the second set of runs, I moved my aerobars from 4" apart to 3-1/4" apart (moved each of them inward 3/8", or 9.5mm). It was definately enough of a change to feel on the bike. I felt narrower. I didn't expect to see a difference in CdA from the Chung testing, but I did. My next task is to do repeat runs on different days to check precision/repeatability.

I trimmed all my data away except for the climb and the descent for each run, and I reset each run's virtual elevation at the known elevation.

The Chung Method is No Joke

I did TT tests yesterday at my Brookhollow course. When messing with the data last night, I came to the conclusion that my test hill must be four feet higher than the 83.1 vertical feet it was designed and staked out to be. Increasing the vertical drop by 4 feet was the only way I could get everything to work out with reasonable Crr and CdA numbers.

I couldn't stand the suspense, so I took a survey instrument (my trusty Topcon GPT-3000 W, shown at left) out there this morning to check it out. Guess what? The contractor built the road with 3.51' more vertical drop than it was supposed to have according to my design (I guess he wanted to save some cash on fill dirt).

The Chung Method is definitely no joke if you use it right. I don't know what Garmin Slipstream pays for tunnel time, but I think I have a comparable tool now for free.

I moved each of my aerobars inward by 3/8" yesterday, and apparently I was able to discern the difference in CdAs from that tiny change (which, by the way, would mean 11 seconds in a 40k TT). If I can see that type of change, this process is going to be fun (and fruitful).

More details to come.

Chung Spreadsheet - Better Acceleration Calculation

The CdAs I calculated for my road bike seemed a little lower than what I would have expected. After reading 106 miles on my Power Tap odometer yesterday for a Claxton Century course that was advertised as 104 miles, I figured the problem might be my PT odometer. I did a very accurate 3-revolution, weighted calibration of my PT wheel this morning and found the circumference to be dead on 2100 mm. I had had the PT programmed to 2098 mm. That means I'm going 2100/2098=1.00095 times as fast/far as I'd thought. Not only is that probably insignificant, it would LOWER my CdA calculations, not raise them. (A quick check revealed that my fastest CdA - when I was in the drops - was lowered by 0.001 m^2 by accounting for the PT circumference change). So I can scratch that as a significant source of error, although the fact that I picked up any change in CdA at all from a 0.095% change in speed is surprising - this method really does provide incredible data resolution).

Then I read Dr. Chung's comment on my last post: He noticed that I had used a simple approximation of acceleration in my Chung Method spreadsheet. To calculate acceleration, I used: change in velocity from T1 to T2 divided by the time interval a = (t2-t1)/dt.

That seemed correct to me. But he suggested I use a more robust approximation suggested by Adam Haile: a = (t2^2-t1^2)/(2*t2*(t2-t1))

As you can see in the highlighted columns in this screen shot of my spreadsheet, the two methods result in very similar, but differing, values of a.















It turns out those differences are enough to change my CdA calculations significantly. My road bike CdAs for hoods, horns, and drops changed from 0.310, 0.245, and 0.240 to 0.338, 0.258, and 0.255, respectively. Those numbers seem more realistic, although they are still lower than I would have guessed.

My Crr changed from 0.0054 to 0.0055 (a difference that is probably not within the resolution of the method).

I think I have everything ready now to do some baseline TT bike tests. Then I'll begin to tinker with my position and see what happens.

Chung Method Aerodynamic Testing

I've always wanted my own wind tunnel. Now I sort of have one.

A couple of years ago I read Robert Chung's presentation, "Estimating CdA with a Power Meter," on aerodynamic testing using nothing more than a known road profile, internet weather info, a bathroom scale, and a power meter.

I remember finding it interesting at the time; but I didn't follow up because I didn't have a power meter on my TT bike. And I didn't really care what my CdA was on my road bike.

A few weeks ago, I read about Colin Griffiths's recent Chung testing in the UK. I now have a Power Tap wheel that I can easily move to my Cervelo TT bike, so re-enter Chung testing.

Basically, Robert Chung took the equation for all the forces acting on a rider: power, air drag (CdA), rolling resistance (Crr), and gravity:

w = wrr + wPE + wKE + waero
w = Crr m v g + s m v g + a m v + CdA ρ vair 2v / 2

and he solved the equation for slope:

s = w/(m g v) – Crr – a/g – (ρ CdA v2)/(2 m g)

Then he used slope and known horizontal position at each time interval to build a virtual profile (using a spreadsheet). By adjusting values of CdA and Crr until the virtual profile matches the real world profile, you are able to solve for both.

Lucky for me, I'm an engineer and a surveyor (lucky in this example, anyway - most of the time I'd rather be a rocket scientist or the base player for the Stones). And lucky for me, a few years ago I designed and staked out a new subdivision street about a mile from my house, so I know the EXACT profile of the road. And lucky for me, the developer has barely sold a single lot in the subdivision, so there is ZERO traffic. And lucky for me, the profile is a perfect U shape with cul-de-sacs at each end so that I can turn around at both ends without touching the brakes. And lastly, the road is very well protected by tall pines, reducing any minor breezes that might interfere with my results.

So as a test run, today I Chung-tested my Tarmac, and I got perfect results. Here's the procedure:

Get on the web and get the temperature, pressure, and humidity for the test location.

Dress for riding and weigh yourself with your bike, bottles, everything.

Ride a known profile (really all you need to know is the elevations of the high points and low points).

Keep EXACTLY the same position on the bike for the duration of the test.

Do not ever touch the brakes - the formula can't account for deceleration due to braking).

Record several runs over/through the known profile.

Return home and record weight and weather data again and average start/finish numbers.

Set up a spreadsheet to plot a virtual profile of your course using the Chung Method.

Adjust the CdA and Crr until you get a constant amplitude and crest height.

Here's a screen shot of the spreadsheet I created to do all of this. Download it from my eSnips account if you want a copy.

It worked like a charm. I did three runs of the course in each of three different positions: 1 - on the hoods; 2 - on the "horns" (hands wrapped around the tops of my Shimano shifters and elbows sort of low; and 3 - in the drops.

I did a trial-and-error adjustment the CdAs for all three positions to get an almost perfect and consistent profile. What little profile variation I saw was likely due to a very light breeze or hitting a rock in the road. A little tweaking of the Crr (rolling resistance coefficient) got the amplitudes right.

Here's what it looked like when I was done. Remember, this is a VIRTUAL profile. It's not measured elevations, it's calculated elevations assuming all the different forces on the rider. It looks to be so accurate and precise that I could literally use it to perform asbuilt surveys on finished roadways (Causey will find that idea intriguing, I think).

The fact that it worked is cool enough. But now comes the fun part: using the new technique to play around with different positions and equipment on my TT bike.

I also learned something very interesting and useful that I will use while training and racing on the road bike. I've always wondered how much more aerodynamic it was to ride in the drops as compared to on the horns. On the horns is so much more comfortable and seems more powerful, too. I turns out that my CdA on the horns is a LOT lower than on the hoods (somewhat expected), and only very slightly less aero than riding in the drops (I was surprised the difference was so little).

So there will be no more training or riding in the drops for me. The almost immeasurable benefit isn't worth the more aggressive, less comfortable position. I'll just ride on the horns. I guess I'll only use the drops for standing and sprinting.

Trainer vs. Road

Ok - this is a work in progress. I don't have as much data as I'd like to have, but the general trend is clear. The problem with collecting additional data is that my aerobic system is improving, which makes establishing a true best-fit line a little like trying to hit a moving target. But you'll get the gist of it. The magenta line is a best fit for trainer data. The red line is a best fit for road data.


The not-so-surprising result: it's harder to ride the trainer than to ride on the road at the same power (all the power data was collected using my Power Tap). For now I'll target my training zones on the trainer using a target heartrate along with the trainer curve to get a target power range. Later I'll do a CP30 test on the trainer, set up power zones from that and see how they compare to the first method. I find it interesting that the difference in NP vs AHR is lower close to threshold than at lower efforts. I would have expected the opposite effect.


Gotta do something to keep the trainer workouts interesting, right? But I have discovered a new indoor toy for indoor rides: I downloaded the new Computrainer scenery pack. Now I can ride cyclocross trails through downtown Atlanta scenery. That's different.

2010 Annual Training Plan

Here's my plan for 2010. Those of you familiar with various popular training approaches will recognize this training philosophy and structure as Joe Friel's. I used a Friel plan in 2006, but that doesn't really count because I didn't start training for cycling exclusively until April 2006. So this will be my first full year on an Friel-based structure.

The most significant changes from my 2008 and 2009 plans are:

• A greater emphasis on macroperiodization -- base1, base2, et cetera as shown below.


• An increase from 425 training hours per year to 505 training hours per year.


• A greater emphasis on weekly microperiodization (rest weeks following work weeks).


• Re-introduction of strength training. I lifted for 10 weeks in winter 2007/2008.


• Strength maintenance work throughout the season.
  

By May I'll know once and for all if Friel's philosophy works.