La Vuelta: Final TT

Don't know if anyone has been following the Vuelta this year, but I have. I thought those consecutive mountaintop finish stages were top notch. Great drama, and interesting to see how the big doodz approached those final climbs.

Anyway, the final TT was pretty exciting! Great fun to see the final results of the penultimate stage of the vuelta and the limited "still" photos on the interwebs.

I was stoked to see Samuel Sanchez (who has tested at the wind tunnel here in san diego with me during the winter for the past couple of years) get a great result in the final TT, and a super finish on the final GC (y'know - I think Samuel is the one person I've spent the most time in the tunnel with over the years - Orbea/Euskaltel invest pretty well in their GC riders when it comes to TT performance):



Also, from my perspective, it is really interesting to see how final TT stage winner David Millar (with whom I've tested with here in san diego) has evolved things over the years. It's wild to see how he has been influenced by various folks over the past three years - in the end, though, he proves that "faster is faster" - glad to see him finally win a stage in a grand tour.

Here's a pic of David and I when he tested with Saunier Duval a few years back:

Label the Intensity Metric Plot

I was pointed to a version of this graphic over on a thai forum:



I couldn't figure out the source of the info for the graphic since it wasn't cited, but it was an interesting plot for me to consider and think about in the context of this forum discussion:

http://biketechreview.com/forum/viewtopic.php?f=1&t=2608

so, are you up for the challenge?

Let's hear what you think are the intensity metric labels for the different squiggly lines in the image above!

If you had to do it again, what would you do differently?

The title of this blog entry is probably my second favorite question I like to ask folks who have recently completed a goal event/project...y'know, it's a good question for us curious folks to pose to people who have spent some time and energy striving to achieve a goal that really means something to them. It's an opportunity for us all to learn, so to speak.

Though, really, it's not a very good question to ask someone who, on a whim, decides to give something a go at the last minute. These style of folks probably didn't give what they did (their "execution"), or how they approached the goal (their "process") much thought - so, the answer that these folks might give doesn't really mean much, I reckon...

but...the folks who put some effort into the deal...well, I reckon I'd be a bit curious about what I could learn from them and their experience. So, yeah, I think the title of this blog is a good question for these folks.

Case in point: Jordan Rapp - recently crowned 2009 IM Canada champ. I haven't asked him this question after his IMC effort. Nor do I expect that I'll get the chance to. Who knows, though, about that...I mean, I did get a response from him after this blog entry:

http://www.biketechreview.com/kdublog/2008/11/ironman.html

so, maybe he just might indulge me! lol! :-)

But really, I reckon the more interesting time to have asked "the question" to Rapp might have been after his second attempt at IMAZ last fall. Here's how I would have expected him to answer "the question" after IMAZ 2008: -> "focus more on the run".

If, indeed that would have been how he answered that question last November (2008), his result today in Penticton (August 2009) wouldn't be that surprising.

FWIW, I'm not too surprised.

Though, I am curios to see what he might be able to do in the future if he ever explored the "faster is faster" process, rather than the "optometrist" process (which Mr. Rapp is obliged currently to promote) as it relates to how one ought to sit on a bike.

The topic of how to sit on a bike has evolved over a hundred+ years, and the modern day tools - such as a power meter and a wind tunnel - have suggested that history has gotten things pretty much "right".

Well, that's what the demand side data from n=100+ athletes in the wind tunnel (and n=1000+ runs) has suggested to me anyway. Granted, this is only the demand side of things, but once one considers how much "supply" is necessary/targetted for an IM effort, well, that sort of thing becomes secondary, I reckon.

Though, really, in the grand scheme of things, I'm open to all sorts of ways to play around with how one might try and sit on a bike...and, believe me, in individual cases, I've seen things that buck the trends. Which is why I sort of chuckle to myself when I hear the "certainty" and "precision" of some folks out there on the interwebs when it comes to how one "ought to sit on a bike"...

Hence, "faster is faster" is the process I prefer to promote.

All of this, as it pertains to Rapp, is pure speculation on my part, of course, but hey - dood just won IMC, so congrats to him on a fine performance.

To personalize this a bit on my end...if I were to have asked myself "the question" (and believe me, I've already done this a number of times! :-) ) after my IMAZ performance last fall, I reckon I'd have said: "focus more on the run".

so, yeah...What's my "caveman" summary about the whole Ironman deal?




More often than not, on the day of the event, long course triathlon isn't really about the bike.




Next week, I think I'll jot down some of the specifics of what I did for IMAZ 2008 and what I'd have done differently knowing what I know from experiencing the whole deal.

elites might find these thoughts irrelevant...but then again, non-elites might also find them irrelevant! :-D

Regardless - the IM deal last summer/fall was "my" n=1 experience...and I guess my big hope would be that someone reading can learn, or better yet/more importantly - think about their approach a bit more deeply.

That'd be pretty cool, huh!? Thinking more deeply about process stuff, and whatnot?!

Field Testing: on-road rolling resistance

I just got back from a little vacation - it's always nice to catch up with family you haven't seen in a real long time...and that whole vacation thing can sometimes be a bit re-energizing too!

Here's a pretty neat shot I managed to snap of a small cabin in the woods that we were helping to stock up in Northeastern Oregon last week:



Hey, now that I'm all re-energized and whatnot, I decided to take another look (kind of in aggregate) at the data I gathered in this BTR Forum thread:

http://biketechreview.com/forum/viewtopic.php?f=1&t=2552

All in all, thus far, I have managed to do 6 runs at 140 psi and 4 runs at 120 psi on a road that I would characterize as pretty rough. There's a picture of the road surface in the thread linked above, so you can make up your own mind, though.

As it turns out, the 140 psi runs on the road had an average Crr that was ~10% lower than the 120 psi runs.

Interestingly, I also tested the same tires on my smooth aluminum rollers in the garage just after these on-road field tests...and not too surprisingly, the 140 psi run was around 8-10% lower in it's Crr than the 120 psi run.

One might also expect that the on-road Crr values would be higher than the smooth aluminum roller case...and, indeed the on-road values were in the 35% higher ballpark. So, that'd mean that if one was using the Crr values here to estimate things/tradeoffs:

http://www.biketechreview.com/tires/AFM_tire_crr.htm

you might only have to multiply the crr of the tires by 15% or so...more work to be done on this topic, though, eh?

These preliminary results are encouraging to me, in that things seem to be consistent (trend-wise). It's good to pursue multiple, independent, lines of inquiry when exploring a topic, eh? But dang, this field testing stuff is pretty tedious and just about as much fun as watching grass grow! :-)

In Summary:

-140 psi was a wee bit faster on average than 120 psi in this comparison
-rough roads seem to have a higher Crr than smooth rollers
-field testing in order to determine Crr is difficult and boring business

Old Chain vs New Chain

This deal is nothing new, really...

Probably 5 years ago or so, a guy sent me a bunch of data that used an external dynamometer and a bunch of different SRM's and PT's that suggested, statisticaly, that a new chain would save a handful of watts compared to an old, worn-out chain. My memory seems to be fading these days, so don't quote that "handful" of watts or anything, OK? ;-)

Well, I don't ride much these days, and so, I reckon that means I don't go through a bunch of equipment like I did back in the day. So, I've got that going for me! A month ago or so, I busted out my chain length checker and found that the chain was in desperate need of replacement.

I'm pretty sure this is the first time I've needed to swap out the chain on this bike - which I built up in Q2 of 2008 or so? But, I've always wanted to independently check the data that the guy previously mentioned had shared many moons ago. The exercise just never was convenient, as I don't really like to ride around using both the PT/SRM, since the PT I have is 9 spd and all and I'm riding 10spd stuff these days. That kloodged together setup still works, though, suprisingly.

I gathered simultaneous SRM/PT data on the road for a few weeks prior to getting on the rollers yesterday and doing a bit more of a controlled test. And during this process, I finally got a chance to use a new bike tool for me - a master link separator that I got from these guys:

www.skabtoolz.com

the last time I tried to gracefully remove a master link, I tried to use a regular pair of pliers and wound up taking a chunk of flesh out of my hand! Then, I proceeded to break the chain the old fashioned way.

Let me tell you, those master link pliers worked like a charm - stick 'em around the master link, apply a bit of side pressure to the master link...squeeze the pliers shut, and boo-yeah, broken chain.

I didn't wind up spending a whole lot of time taking data on the rollers with the old and new chains, but the little I did does seem to suggest that there are indeed a few watts to be had when going from a worn-out kinda krusty old chain to a brand-spanking new SRAM 10spd chain.

More details and protocol nuggets about this mini-test can be found in this thread over on the BTR Forum.

Amour de "Low"

I'm not sure how to spell "love" in french - it's Amor in spanish, and Amore in Italian, that much I'm sure of, and so, well, I reckon it's probably close to "amour" in french...

Anyway, after watching today's ITT in the tour, I'm pretty amazed at how much of the peloton is demonstrating behaviors symptomatic of the "disease of lowness". By that, I mean all the guys who wind up riding the tip of the saddle, only to shift themselves back on the saddle every 5 pedal strokes (I don't know what was more painful - how Contador felt during the ITT or how I felt while watching the DVR'd coverage a few minutes ago). The funny thing, for me, after seeing first hand how reach and drop interact in a wind tunnel with a wide cross section of athletes (from elites like Kristin Armstrong, Sarah Hammer, Phinney, Hincapie, Astarloza, Leipheimer, Popovych, Danielson, Marchante, Simoni, Millar, Sanchez, etc.. etc... to masters National champions like Ruth Clemence, or Alpenrose kilo record holders like BTR member Snigelmannen - way to take the record from Marty Nothstein! - to IM folks like Sindballe, Evans, Andersson, Fuhr, Ferguson, Major - to chubby, amateur, wannabe time trialists/IM'rs named Kraig) is that this disease has a cure...

The cure is simple, and it's called raising the bars in order to decrease the drop. huh? I mean, everyone knows that if you want to be aerodynamic, you have to have lots of drop, reach be damned, eh?

The favorite refrain from the "prophets of low" is: "move the saddle forward" or "get steep" isn't it:

http://www.biketechreview.com/performance/faster.htm

Move the saddle forward and drop the bars "a little", or get "steep" is the magic elixir for the sickness of being too low, according to the pundits. Well, yeah, that seems like kind of an indirect way of solving the "bars are too low" issue, eh?

The fact of the matter is that from an aerodynamic perspective there exists a relationship between reach and drop for each individual, it's not an either/or deal...and despite what the interweb forums are full of, the UCI really isn't limiting things in the "forward" department based on my experience.

I'll use myself as an example of the "disease of lowness" - the last time I tested my TT/IM position in the wind tunnel was just a week or so after my IMAZ effort last november. During that test, I baselined my position, then looked at how reach and drop interacted. At three different bar heights, it became clear that if I "tipped it" (riding the nose of the saddle, rather than sitting on the saddle square), I was less aerodynamic than if I wasn't "tipping it"...and despite lowering the bars (more than "a little") the most aerodynamic overall position came at the highest bar height I was able to achieve - this bar height was probably a couple cm higher (or more) than the position I used for IMAZ.

These tunnel data suggest that if I were to take the advice of the "prophets of steep and low", (i.e - you just need to "move the saddle forward, and maybe drop the bars a little") well, I would be less aerodynamic and, therefore, slower. Thanks for the blanket, mantra-driven advice, but I think I'll pass, and let the beta/yaw equal to and not equal to zero data speak.

So, yeah, I can't really be bothered by all the "get low shenanigans" or "get low theatrics" the pro peloton seems to be brewing up these days. The wind tunnel here in san diego is the medicine that cured me of my own personal "disease of lowness". Keep in mind that I'm not alone with the uniqueness of how my reach/drop interact. Others demonstrate this same unique trade-off (some are listed above) of reach and drop from an aerodynamic perspective.

If one takes a "forest driven" rather than a "tree-driven" approach or process to TT setups, one just might realize that there exists a real opportunity to explore how much power one can produce (or wants to/chooses to produce in the case of IM) for the duration of their intended effort as a function of different reach/drop combinations.

I mean, if one can raise their bars, extend their effective reach, be more comfortable, be more powerful, and have the same (or better aerodynamics), well then, that sounds like a pretty good deal to me.

In the end, I'm pretty much enamored with "fast" and am not burdened by "the disease of lowness" anymore.

Kind of along these lines, I'm pretty sure LANCE demonstrated today, that once again, it's not about the bike...it's really about the floppy, un-aerodynamic jewelry hanging from your neck!!! ;-)

(and yeah, I think LANCE needs to raise his bars back to where they used to be four years ago... ;-) )

Wow!

...that's the hip, errrr.... kinda odd ad campaign the Trek folks are running during the US coverage of this years Tour:

http://www.trekbikes.com/us/en/

while researching that link above, hey, check this video out that I found:



and this screengrab :30-odd seconds in...so, is that CxA value below for Contator, Leipheimer, or rider "misinformation X"...




anyway, "WOW!!!" is about all I can say after seeing what happened today between kloden and the NEW LANCE and what happened four years ago by my calcs:

http://www.biketechreview.com/performance/la_cant_doit.htm

and, within that article this image strikes me as the heart of "WOW!!!" :



yeah... WOW!!! That's a big reversal, there between Kloden and the NEW LANCE, eh?

Kloden and LANCE

I was watchin' the tour coverage this morning as events transpired...it was pretty amazing to see Kloden and LANCE, two, what I perceived as, bitter rivals of the past - remember stg 17 of the 2004 TdF:



Anyway, to see these guys "teaming up"...well, that's a bit strong, I reckon...I mean, one of them was working on a salary basis setting tempo for the other who was dropped, and limiting losses...the LANCE, well, let's just say it's a safe bet that he's probably betting on something longer term, financially, than this year's efforts, with a higher ROI than the UCI minimum salary, eh?

Anyway, pretty crazy to see how someone who allegedly/is accused of taking on blood transfusions three years ago:

http://autobus.cyclingnews.com/news.php?id=news/2009/may09/may13news3

stacked up against LANCE on the alpe d'huez four years ago:

http://www.biketechreview.com/performance/la_cant_doit.htm

and more specifically this chart within the linked article above:



Which estimates (hey, that's an estimate, lawyer guys, eh?) LANCE at 6.4 w/kg and kloden at 6.0 w/kg. The NEW LANCE is going better than he was during two of his 7 previous victories, according to pre-tour interviews, though? As Trek likes to say during their tour de france versus coverage: "WOW"...

both of these guys (Kloden and Armstrong) are getting a bit long in the tooth (kloden is 34 while the NEW LANCE is 37 - which is, hey, the same age as yours truly - so I guess I know a thing or two about how performance at 37 rates against performance 3-4 years ago...or heck, 10 years ago for that matter...), but, how today's events transpired became a bit of a head scratcher for me, given all of that previous data/information... Though, now that I think about it a bit, well, I'm pretty sure Kate Hudson is what is behind it all for the NEW LANCE's performance:



Bring on the new generation of bike racing and bike racers - can't wait to see how things shape up 10 years from now!

Bring it!

Wiggins Stage 1 - Tour de France TT

the Garmin boyz posted Wiggins' tcx file from the first stage of the tour, so I made the same plot as I did for the Giro TT.



yeah, some linear power variation with slope there, eh?

I've got some more plots from the stage 1 TT I've been playing with over on the forum. Check 'em out here:

http://forum.biketechreview.com/viewtopic.php?f=1&t=2560

Palomar!

Well, it'd been quite a while since I've climbed Mount Palomar in any sort of fashion...So, I decided to give it a go in order to understand how bad things can get at the nadir of my fitness! Here's my "aww...man, this pretty much sux" face:



;-)

http://www.rickclemson.com/UploadScript/Gallery/CM_70759.jpg

I've never met Amber Neben before, nor seen her in person...but, if I was making a bet, I'd say I saw her yesterday doing repeats on Palomar. I saw her about 7 minutes into my effort on the way up, and then again after I bailed and was heading back down about an hour or so later...not too many people do repeats on Palomar these days! Can anybody confirm that it was Amber who I saw yesterday git'n 'r dun on this big ol' hill in N. SD county??

Well, despite my best efforts, I was only able to give a maximal effort for around 43 minutes - I couldn't continue past that at the pace I was wanting to do -> now, that's what I would call a maximal effort for the duration, eh?!

uggh-yeah, this effort was confirmation that I'm not going so well at the moment -> I'm up in KG's and down on power -> which is a pretty good recipe for slowness up Palomar! :-)

So, for 43 minutes I made 269+/-W -> after 15 mins it was ~ 276W -> at 30 minutes it was ~273W. I tried my best to make it an even effort, but dang, I just can't make the watts I'd like to be able to right now.

Good news is that these 265-270W are about where I thought things were based on my recent 20MP efforts up Couser Canyon -> which had me in the low 290's or so. Good to know that my perceived exertion and ~20MP efforts are still aligned in terms of predicting my 50-60MP!

Here's the kicker for all the gizmo power fans out there...This past Wednesday - or maybe it was Tuesday - after a hard days worth of sitting behind a desk git'n all puffy and stuff -> I was able to rip off a non-maximal "scatter the plot" type of ride that posted a gizmo power in excess of 300W for 55 minutes. At the time that made me chuckle a bit inside, to be honest. That'd be a gizmo power to average power ratio (non-maximal GP vs maximal AP for the duration+) in excess of 1.1X -> does that satisfy one of the "many" definitions of a "gizmo power buster"??

In order to be thorough, though, I backed up that kinda large standard deviation effort with a maximal steady state deal up Palomar. Oh, yeah, BTW, I'd say I probably stood up on the pedals more during my effort on Palomar than I did during the mid-week ride -> I probably did stand up on the recovery portions of the mid-week ride, stretching/shaking out the Pro/E bugs! ;-) How should we correct for that?!

In the grand scheme of things, I guess I still don't see the relevance of "pinning a single number on the deal". Y'know, I see these type of rides as two separate deals -> one "fills the right" and the other "scatters the plot". But neither of these rides really focuses on "raising the left", which is where I've found things to be at when it comes to racing bikes on the road/doing Ironman Triathlons while preparing for these style of efforts with minimal time investment.

If I were estimating my maximal 60MP right now, well, then, I guess I'd put it in the 265-ish range based on the supercomputer and what I've actually been able to do in practice -> which, FWIW, is an all time low by about 5W or so... Not so bad considering I've not really gone hard in awhile...though, I have been doing primarily 75-100 minute rides where I just ride kinda hard/tempo -> I guess this is further reinforcement that for me, "filling the right" doesn't really enable "raising the left".

Anyway, some stuff for y'all to consider (or dismiss as some folks will be wont to do!).

YMMV,

-k

Wiggins Stage 12 - 2009 Giro ITT

I was turned on to a power file for Bradley Wiggins' effort during the stage 12 ITT of the 2009 Giro d'Italia:

http://anonymous.coward.free.fr/wattage/Wiggins-Giro09-12.csv

Here's a plot I quickly whipped up:



definitely looks like he has some trending going on when the road tilts up, there, eh?

By my figgerin' he ramps up his watts by around 2.5% per % of incline for this effort (when slope is positive or flat). With a little work, we can probably also parse out the bits where he was braking and whatnot, cuz, yeah, it gets a little ragged when the road starts going downhill, eh?

Interesting too, to note that he spent roughly 2x the amount of time going up/flat compared to time spent going downhill - and the splits pretty clearly indicate that he lost gobs of time on the second uphill portion of the effort.

Until next time!

The words in that picture at the top of this page

I got a good reminder of it this past week during a discussion on the BTR forum. I made some off-hand comment about aero helmets and the stage 12 giro TT. Well, it turns out that that picture at the top of this page has got it about right.

check out the thread here if you are open to the possibility of seeing things from a different perspective:

http://biketechreview.com/forum/viewtopic.php?f=1&t=2532

on another note - hey, it's pretty crazy to think that the structures guy (check out the downtube on the giant):

http://www.cyclingnews.com/photos/2009/giro09/giro0912/PIC31528576.jpg

made the aero guy:

http://www.grahamwatson.com/gw/imagedocs.nsf/2ad5fc39030e64aa86256c8600642e1a/bbf308cffdd4279e862575bd006b9e82/$FILE/4.jpg

look silly on this stage. ;-)

Aero Torque/Watts to Spin

This aero torque topic has been on my list for a long time. I've tried many different ways of gaining insight into the deal over the years:

1) reported texas a&m wind tunnel motor measurements
2) srm power meter driving rear wheels in calm air
3) coast down of wheels in a truing stand with a fan blowing
4) srm power meter driving rear wheels with a fan blowing
5) srm power meter driving rear wheels while I stood in the bed of my pickup and my wife drove around at 30mph

more recently:

6) on a really windy day (30mph gusts) I did the srm power meter thing
7) monitoring the motor (that is used to spin the wheels) power during wheel/tire tests in the san diego wind tunnel
8) using all six force and moment component data from the wind tunnel balance during same test described in #7

I've found several independent references on the internets:

http://www.recumbents.com/WISIL/MartinDocs/Validation%20of%20a%20mathematical%20model%20for%20road%20cycling.pdf

estimated two wheels need additional 3-4 watts at 40kph 6-7 watts at 50kph

http://www.soton.ac.uk/~aijf197/Wheel%20Aerodynamics/Results%20and%20Discussion.htm

estimated one wheel to need additional 5-9 watts at 40kph

http://journals.pepublishing.com/content/g1463815454723l0/

estimated a single wheel requires more than listed above (research funded by a wheel manufacturer)

There also used to be a thesis from the same university as the latter link above that included CFD work here:

http://ir.canterbury.ac.nz/handle/10092/1800

(research funded by a wheel manufacturer)

But they have since removed the document until October of 2010. The first time I followed the thesis link in maybe December of 2008, I was able to download, save, and read the paper and the rotational watts are similar to what was reported above – though, they include wind tunnel measurements (translational/rotational) for the zipp 808 and hed three spoke. The manner in which these researchers gathered their rotational power data is clever (the motor they use to spin the wheel in the tunnel is mounted on a force platform that monitors things), and does not use the data acquired from a six component balance.

Based on my SRM tinkerings, I’ve really not been able to discern more than a few watt difference between wheels – independent of whether or not there is ambient wind present (and the numbers on the plot below include drivetrain losses):



This past time in the tunnel, I made the mental commitment to reduce the wind tunnel force and moment data in such a way that it not only reflected the translational resistive force, but also the aerodynamic torque – or “watts to spin”.

I won’t bore you with math and whatnot related to how I independently approached this topic using force/moment wind tunnel data (I'm not the sharpest tool in the shed, so I reckon it took me quite a bit longer to figure this one out compared to the big dawgs at the wheel company's - and I probably stuffed something up along the way :-0 ), but it seems as if the rotational watts can account for a chunk of the whole "fastest wheel" deal. For an estimate on the magnitude I came up with you might want to check out the insider's forum for discussion/further insight.

I’m not sure what to make of this independent finding. It’s encouraging that one is able to use force and moment data to repeatably measure this aerodynamic torque value and this fact will more than likely prompt me to investigate wheels that are different than the three spoke and the 1080 in the future. I would expect wheels like the HED 90 and 808 and shallower rim/longer spoke wheels to get rotationally bad at a relatively faster rate.

So, maybe the data here:

http://journals.pepublishing.com/content/g1463815454723l0/

Is on target?

"Fast" TT/Tri Geometry - Part One

Thanks to the guys over at Slowtwitch.com, us regular/caveman folks have access to a database of TT/Triathlon frame geometries. This is pretty cool, and I'm glad those guys have taken the effort to put this together.

It's always intriguing to me when datasets like this are published, as I think a closer look can reveal an additional layer of insight. But, I'm never really sure about this until folks other than the original publishers actually dive into the data.

It's great that these guys publish this data, don't get me wrong, but I think it stops short on the whole global "TT/Triathlon" positioning deal - I mean, a bike manufacturer has a definite "fit philosophy" when they ship a give frame geometry to the general public, don't they?

For all intents and purposes, it seems, that each bike manufacturer thinks their own "fit/geometry philosophy" is the "best" way to make their customers perform optimally (or at least I hope the mfr's are not hoping to make their customers slower!). So, which mfr is "correct"?

That's really the question I have, when it gets down to the core of the whole deal... What does the mfr frame geometry say about the mfr, and in the end, which frame geometry is faster than the rest.

As a first step in this frame geometry journey, let's just look at the raw data as provided by slowtwitch.com, but in a much more digestable, non-tabular format:



yeah, so it seems to me that there's a bit of spread with this data, eh? It's interesting to note that for a given slowtitch "reach", (which is kind of, but not completely, related to how I define "reach") or distance from bottom bracket to the top of the head tube at the centerline of the head tube longitudinally, you can see that some manufacturers have pretty diverse opinions on the whole deal of "fast geometry" from a positioning perspective. Who'd a thunk it, eh?

I mean, these days consumer products thrive on diversification, so it is to be expected that mfr's will attempt to "be different" than their competition and subsequently make claims about how their approach is superior to their competition...

But I digress.

Having had the opportunity to test lots of normal and elite folk in a wind tunnel while measuring different things about how their bikes are set up, I'm in the kind of unique position of trying to attempt to say: "these bike geometry variables will tend to improve, or hurt a rider's aerodynamic position". To put it another way, I've accumulated a lot of wind tunnel data over the years that suggests a thing or two about what is responsible for making a rider aerodynamic.

We'll get to that later, but IME, CxA(a measure of aerodynamics of a given position/geometry)from a positioning/bike geometry perspective, can be boiled down to the following variables:

saddle setback (tip of saddle relative to bottom bracket)
saddle height
reach (distance from tip of saddle to where the aero bars are grasped)
drop (top of saddle to elbow pads/elbows)
pad width

There are, of course, some other things that affect the whole deal, but they aren't really a function of a bike frame's geometry.

It seems like there might be an opportunity here, then, to attempt to draw a connection between how mfr's design and sell bikes, how consumers set-up these bikes, and how the resulting positions are measured from a CxA perspective in a wind tunnel.

In my next blog entry, I'll try to step through the logic of how I would rate mfr geomety decisions along the "fast-ness" spectrum.

Be well,

-k

My Lunch hour ride today...

...bonus points for those that can decipher the 3-d histograms below (they are the same plot, just from different perspectives)!






ooooh - look at the pretty colors! :-)

I haven't fired up this matlab script in awhile, but when I do, I find that it's a pretty descriptive way to discover the "gold" in my srm files.

From the looks of it, it seems that I can do about 13+ minutes @ 6+W/kg in 70-80 second chunks in around 40 minutes.

Sprints with the PowerTap

I mentioned some oddities I experienced with the powertap I currently have on the bike I'm riding a few posts ago - ya'know, the whole exact same power readings during a sprint deal.

Here's a a screenshot from the download of yesterday's file where I was doing some sprints:

one thing to note is that when I stopped pedaling, I then glanced at the PT head unit as I was coasting - it kept reading the same value for a bit - and this observation is reflected in the download.

So, this observation would suggest that the PT is doing some unknown filtering in their data acquisition. This could be good, or it could be bad - in the case of short efforts , it appears that it's doing some weird things as it relates to reality.

Not that this sprinting observation really matters in the grand scheme of things (it's been kind of refreshing for the past couple weeks not to give any credence to the flashing numbers on the power display!) - but it is a worthwhile thing to note.

Speaking of power meters - did y'all see the dueling press releases from ergomo/gita this past week?

Guess that is a partial explanation as to why I never got an ergomo to evaluate from the "important folks" at ergomo-usa. Then again, the excuse I continually got was that "there just isn't any availability right now for demo's" - or words to that effect - which from the sounds of the Gita position is a factual statement...

Anyway - I reckon my original thoughts on the ergomo still have some relevance:

-measure one leg and double it and all the doubt that that brings up

-ease of installation

-reliability of "zero-ing" out the unit prior to riding

-measure one leg and double it and all the doubt that that brings up

did I mention "measure one leg and double it and all the doubt that that brings up" ;-)

Seriously, though - I reckon if a gadget helps you ride your bike more intelligently/purpose/reliably then that's a good thing.

I used to keep training logs back in the day where I'd actually write things down - that was a good tool to make sure I was doing what I had set out to do on a given day. Nothing like the satisfaction of writing down HR's and times and distances and RPE's in that journal entry for the day!

Downloading a power meter file can have a similar effect on training, in my experience.

Power File Databasing

Spent a wee-bit of time figuring out how to decode the binary bits and bytes of the SRM power meter file format.


Great insight and c++ code over at goldencheetah.org.

Here's the first little bit of code in the script I wrote for batch importing SRM files and creating a matlab database for subsequent analysis:





With this piece of code, it's pretty easy to simplify big jobs like putting together plots like the following for 300+ power meter files (this plot was kind of inspired by Dr. Allen Lim of the Saris Group in this Q&A tidbit - http://www.saris.com/t-PowerTourQA.aspx#NormalizedPower ):






For those interested in further reading about this plot that orginally appeared in an old article on the main btr site you can check out:

http://www.biketechreview.com/power/strain.htm


not much has changed globally since 2004/2005, eh?


Anyway, this database creation tool I've created is pretty cool - it sequentially opens up each individual file in the native SRM format and processes the data any which way you like - well, at least any which way you can code something up! pretty cool, huh!?

oh, man, I'm a total dork... ;-)