Friday, January 3, 2014

Kona Bike Stats

A common topic of debate is how much faster modern triathletes are today thanks to fancier bike equipment. Some claim that legends like Mark Allen and Dave Scott rode their round tube frames just as fast as today's pros ride their high-tech carbon, aero equipment. Comparing bike performance is a tricky business, as a host of factors make bike times very "noisy." The winds at Kona vary greatly, which can affect bike times by as much as 15 minutes or more. Tactics also affect times, as some years the contenders will all be together on the bike course with nobody pushing the pace. To try to answer the question and make sense of it all we have put together some interactive charts.

The slowtwitch kona archive provides a handy source of data on the top 10 finishers each year since the start of Kona. We chose to look at the time period from 1988 to 2013, as this represents a period when the depth of talent was solid, and the course was relatively constant. It also represents a time after the introduction of the aerobar, when professionals were already adopting bike positions similar to modern athletes. Some small course changes have occurred over these years, but the bulk of the bike course has remained the same. First up, we take a look at the average bike splits among the top 10 overall finishers. Hover over a year for more info, pictures, and links when available.
You can see that there is a clear downward trend in bike times. The linear trend shown in light blue suggests that bike times have improved by 13 minutes, or 4.5% over the time period. However, that isn't necessarily all a result of improved bike gear. Records have been dropping in all sports, even those like running, in which equipment plays almost no role. Since running isn't impacted much by technical advancement, it gives us a great point of comparison. We can compare the trends in the Kona run and bike and see if one has been improving at a faster rate than the other.

If the fitness and talent had been the only thing improving Kona performances, we should actually expect to see cycling improve at a slower rate than running, as the nature of aerodynamic resistance limits how much time is saved by a more powerful athlete. But we actually see that cycling is improving about 1% faster than running at Kona over the time period.

Another way to slice the data is to look at the fastest bike split each year. In this case we took the fastest bike split each year among the top 10 finishers. Anyone setting a fast time and then blowing up on the run is thus excluded. Hover over a point below to see who set the fast time that year.
Again we see a clear downward trend in bike times, almost the same trend as in the top 10 analysis in fact. One interesting property of both the top bike splits and the average bike splits is the consistently slow times between 1997 and 2005. Wind, tactics, drugs, and talent are possible explanations that come to mind, but we really don't know. If you have any ideas, drop us a comment and let us know.

Friday, November 22, 2013

Aero Tuneup Take 2
Cheapass Aero!

Previously we detailed a slick aero tuneup on a Cervelo P2, which was very nice but also a bit expensive with a high priced aerobar, and $300 worth of aero brakes and stems. So here is another take on the aero tuneup from Scott Morgan.

  • Used Vision base bar: $40
  • Used Tektro Center Pull Brake: $45
  • Cable Stop: $5

Here are the before and after shots, nice!

Tuesday, November 5, 2013

The Sum of Marginal Gains

Is it worth it, how much does it matter? Is paying attention to skewer alignment to save a tenth of a second really a useful way to spend your time? Do you really need to pace intelligently or can you just bike "all out"? Do these theoretical rolling resistance and aero time savings really occur in the real world?

I recently had the opportunity to compare two cases, from the same race, on the same day. I had access to the average power, height, weight, and equipment info of two riders who competed in the 2013 Austin 70.3 bike leg. The bike course at this race includes rolling hills, plenty of turns, and lots of imperfect pavement. It is very much a typical real world scenario. The difference was rather startling.

Rider 1
217 watts average
170 lbs
3 hours 10 minutes
17.6 mph

Rider 2
221 watts average
142 lbs
2 hours 21 minutes
23.8 mph

This is a massive 49 minute difference for the two athletes, on the same day, producing similar power.  How much of that can be explained by the difference in mass, size, and power alone?  We can plug this data into the equations of motion of a cyclist along with a reasonable approximation of the Austin 70.3 course and see that size, mass, and power account for only about 15 minutes of the difference at most. This leaves 34 minutes unaccounted for over the 56 mile course. Both riders were on entry level TT frames, and used their aerobars. 34 minutes.

Where does that time difference come from? A few minutes plus or minus could be attributed to power meter error perhaps. The rest comes from the sum of marginal gains, including some of the following, but not limited to, and in no particular order:

Rider 2 put a lot of effort into her bike setup, rode the course ahead of time, and had an intelligent pacing plan and this paid off.  Rider 1 is already well on his way to improving and I expect will surprise himself in the near future.

Friday, October 25, 2013

Aero Tuneup

by Jack Mott

Some of us get attached to our older bikes and, happy in our long-term relationship, see no need to spend thousands of dollars on a newer and more expensive model. One can get very envious, though, of contemporary super bikes like the Fuji Norcom Straight and Cervelo P5their sleek shapes make our tried-and-true race steed look like it's ready to be put out to pasture. The Norcom Straight and P5 can offer up to a second per kilometer of aero savings, boasting beautiful front ends that hide the cables and brakes from the wind. Fortunately, with a bit of cleverness and careful part selection, you can update the bike you know and love to bridge that aerodynamic and aesthetic gap, giving it a new lease on life.

For our test case we used a Cervelo P2 ridden by Kat Hunter, editor of this blog and ATC Racing TT specialist. The P2 is a great bike, with real aerodynamic engineering, good handling, and a good fit for Kat. However, as you can see in this photo below, compared to a modern super bike, the front end presents all kinds of bolts, cables, and surface area to the wind.

The most important thing to address here is the aerobar. Aerobars must, first and foremost, support your ideal position. After that, pick one that presents the least frontal area to the wind and that keeps cables internal and tidy. Newer versions of the 3T Aura, pictured above to the left, have improved their cable routing so they stay in the bar all the way to the stem, exiting out the back. Look for bars that keep the mounting hardware as minimal and out of the wind as possible. A great budget option is the older aluminum Vision base bar and clip-ons. They use a very aero shape and a smaller stem clamp diameter for reduced surface area. Fancier options with integrated stems include the 3T Ventus II and the Zipp Vuka Stealth.

For Kat's bike we had to stick with UCI-legal options and went with the HED Corsair, which offers a nice integrated brake lever with built-in return spring. We paired it with Vision clip-ons, which are comfortable for her and present minimal mounting hardware to the wind.

Hiding the cables from the wind offers a fairly small aero advantage, but a huge aesthetic one, and is often easy to do. You can do a pretty thorough job just by putting some thought into your cable routing. Experiment with different routes and find one that keeps the cables hidden from view. Often a zip tie or some electrical tape can work wonders to keep the cables tidy.

We went a step further with Kat's P2 and got out a drill. In standard form the P2 shifter cables enter at the down tube, while most newer bikes have them enter at the top tube. We found this handy tutorial from TriRig on how to modify your P2 to accept top tube cables. The procedure is relatively simple, but be warned that this could void your warranty, and this is in no way officially sanctioned by Cervelo or ATC. The same procedure works on both the older P3 and P2, and may work on other bikes as well.

Another neat trick in lieu of zip ties to keep the cables tidy is the TriRig Sigma stem, which offers some great aero features. It helps route the cables cleanly, exposes no bolts to the wind, and has a small, smooth frontal area. It has an optional bottle cage mount, so you can throw away a few more zip ties if you use a between-the-arms bottle, and, lastly, it offers a cable stop for center pull brakes. The catch is that it is only available in 90mm length and two different rises, and you have to cut your steerer tube to the exact height. You can't put any spacers above the stem, so you can always go lower, but never higher.

Installation is not difficult. You cut the steerer tube of your fork to a few millimeters below the top of the stem, mount it with the included top cap, and run your cables over the top of it. If you have a center pull brake, you run the front brake cable into the cable stop in the middle of the stem, as shown below.

Sigma stem, with cover off

Once the cables are routed, you then squeeze the cables together and bolt the cover on. If you have Di2, you can mount the control box inside the cover, facing up through the slot so you can see and operate it.

Sigma stem, with cover on

On the left we also mounted an additional piece that allows you to bolt a bottle cage directly to the stem. If you won't be doing that, you can leave that piece off. The finished product with bottle cage mounted looks like this:

Tektro Center Pull
Retrofitting the integrated brakes of bikes like the Fuji Norcom Straight onto an older P2 or Slice isn't quite possible, but you can get very nearly the same aero advantage with careful part selection.

Magura Hydraulic
A normal brake up front is only about an 8 second per 40k disadvantage compared to no brake at all, and some of the center pull options get very close to eliminating all of that drag. One option is a standard Tektro or Campy center pull caliper. These mount easily, brake well, and are affordable. You will need to add a cable stop or use the Sigma stem to get them working since you can't run cable housing to them.

Another great option is the Magura hydraulic brake. They have top-notch aerodynamics and better braking power than standard calipers. You may be able to find good deals on these at your local bike shop from people who didn't want to go hydraulic on their P5s and new P3s. If you don't want to go hydraulic either, you can use the TriRig Omega brake. It can accept either cable housing or bare cable, so you don't have to mount a cable stop if you don't want to. The Omega has a wind-tunnel-tested shape that, along with the Magura, makes it one of the most aero brakes you can buy today. TriRig was a sponsor for ATC Racing this past year, so of course we went with the Omega.

A bike's fork is one of the most critical aero parts of the bike. Like the aerobar, it is up front hitting clean air, and it affects how air flows around the bike and front wheel. Over time, many bike companies have tweaked and improved their forks. If you have an older model year P2 or P3, an easy upgrade is the latest Cervelo fork. Cervelo claims this fork is about a 1.5 watt, or 6 seconds per 40k, advantage over the best previous generation forks. In fact, any bike with a standard 1 1/8" head tube could upgrade to this fork. Kat's bike had the previous generation 3T fork, so we swapped it out for the new model. If you sell the old fork, this upgrade isn't even very expensive overall.

Final Result
With modified cable routing and brakes, a trick stem, and the latest fork, we have managed to achieve many of the aesthetic and aerodynamic features of much more expensive bikes with integrated front ends. Kat will put the new setup to the test this weekend at the Austin 70.3 triathlon as she competes in the relay category hoping to set a screaming fast bike split. UPDATE: 56 miles in 2:21:21 on 221 normalized watts. Fastest relay split by 6 minutes. Congrats Kat!

Friday, September 6, 2013

LG Course Aero Road Helmet
Stealth Aero!

by Jack Mott

Aero road helmets are all the rage, and previously we covered the slick Giro Air Attack. Some riders, however, are unwilling to defy fashion trends, or are worried about the Texas heat in a helmet with so little ventilation. The LG Course aero road helmet comes to the rescue!

Based on appearance alone, it's hard to believe the Course could be as aero as Louis Garneau claims in their white paper, given that it looks very much like a normal road helmet. But some very good aero testing results have been coming in from ERO Sports. The helmet has tested fast on multiple riders; they report it consistently tested about 2% less drag (over the entire rider-bike system) than the Air Attack, and never slower. This included both aero positions and road bike positions. So we decided to check the helmet out.

We picked up a size Medium from ATC, and on close inspection you can see the trick with this helmet seems to be that it is basically letting the air pass straight through over your head and out the back again. Interestingly, this seems to make ventilation better than most normal road helmets, as both my wife and I noticed we could feel the breeze through our hair more with this helmet as compared to our usual ones. This, combined with carefully controlled frontal area, probably explains the surprising aero goodness. At 250g, the weight is also low, and it fits us both very comfortably. A really neat bonus feature is an included rear light that velcros onto the back of the helmet.

Integrated Rear Light Included
So we have a helmet that is light, aero, ventilated, and includes integrated safety features, but is there any catch? It is a bit more expensive than the Giro Air Attack and doesn't have the cool shield feature as an option. Also, both the white paper from LG and the testing at ERO Sports are lacking any high yaw data, so it is possible that the Course doesn't fare as well in crosswind situations as the Attack's smooth shape does. Overall, though, the Course is an amazing helmet that we recommend highly. ATC has them in stock now, so try it out yourself. The helmet is available in three sizes and in red, white, or black.

CFD Designed, Wind Tunnel Tested

Thursday, September 5, 2013

Pacing on the Bike

by Jack Mott
Missy Ruthven of ATC Racing finishing the Mopac TT

Position, power, and pacing are three keys to a solid time trial or triathlon bike leg performance. Obviously, you want to be capable of producing as much power as possible by training hard. We previously talked about position and equipment setup. Now let's talk about pacing. Optimal pacing gets you the most speed for your available energy. To a very close approximation, the best pacing strategy on a flat course is to hold constant power for the whole course. The most common mistake is to start out too hard because you feel good, which you pay for later.

40k TT - a little too hard the first half, but not bad
To illustrate the kind of time that can be wasted by bad pacing, we can run some numbers through the website Analytic Cycling. Suppose a 75kg rider is capable of producing 250 watts for an hour, and completes a flat 40k time trial with perfectly even pacing. This rider would complete the 40k in about 59 minutes and 24 seconds.  Now suppose that this rider makes the classic mistake of going out too hard and does 275 watts for the first 30 minutes, then starts to blow up and has to average 225 watts for the rest of the ride. This would result in a finishing time of 59 minutes and 32 seconds, about 8 seconds slower for the same average power.  That doesn't sound too bad, but in fact it would be impossible for the rider to maintain that power output of 225 watts after going out too hard.  The harder you push, the bigger the physiological price you pay, and if you start out too hard you will not be able to maintain the same average power.  A more realistic scenario is that the rider would have to drop down to something like 200 watts after starting out that hard, which would bump the time to 1 hour and 53 seconds. Almost a minute and a half slower.

So you don't have to have the new Cervelo P5 to see significant gains. You can potentially save more time by pacing properly than you can by upgrading your bike (of course, you could do both!). All you have to do is practice and ride smarter!  The most sure-fire way to nail your pacing perfectly is to use a power meter, but with practice you can do quite well without one. We will discuss how to approach both situations.

Pacing with Power

The first step to pacing an upcoming TT or triathlon bike leg is to pick a power goal.  For time trials, you should estimate about how long the event will take you to finish, and then look at your past power data to figure out what power you are likely to be able to do for that duration.  The Mean Maximal Power chart (or MMP) is very useful for this.  At a glance you can see what your best ever power production is for a given duration. For example, suppose you have an upcoming event that will take about 20 minutes.  Load up your MMP chart with some of your recent training history. In Golden Cheetah it will look something like this (WKO+ has a similar chart):

Click to Zoom
At a glance I can see that the best 20-minute power I've done is around 280 watts, but I can also see that there is a little bump around 17 minutes, where my best power is 300 watts.  This implies that I've never done an all-out 20-minute effort, and am probably capable of doing a little more than 280.  So a reasonable power goal might be 290 watts for the upcoming TT.  Be sure to take into account weather conditions and your fitness and fatigue levels when setting your goal. Hot weather will often lead to significantly less power, for instance.

Triathletes will usually want to set their power goals by doing practice bricks or by extrapolating from past races.  A great way to set a power goal is to do a bike ride that simulates race conditions as closely as possible, and then do a short run afterwards to be sure the pace left you fresh enough to run well.

Once you have your goal power, you don't want to follow it blindly on race day.  You might be capable of more, or you might have aimed to high. You need to listen to your body to some extent, but you also need to try to defy it sometimes when it tells you to slow down!  Since the most common mistakes are to start out too hard and to give up too soon, I like to use the following protocol:

1. For the first half of the event do not ever go above your goal power, but if you feel terrible, you may go under it.  This is especially important in the first few minutes.  It is okay to surge for 4 or 5 seconds to get up to speed, but then settle down, no matter how amazing you feel. It will pass, I promise.

2. For the second half, never go below your goal power, but if you feel great, start trying to raise it up gradually.  This ensures you won't totally miss out on any unexpected fitness or heroics.  We are all naturally capable of more than we think, so no matter how bad it hurts, never drop below that goal power in the second half, you can do it.

That is all there is to it. With this general approach you can almost guarantee you nail your bike legs and time trials every time. However, don't skip the section below where we talk about pacing without a power meter, because sometimes mechanical problems will leave you without your power meter, and you should be ready to perform well, and without stress, when that happens.

Pacing by Feel

The challenge with pacing by feel is the incredibly strong tendency to start out too hard.  The adrenaline of race day and your fresh anaerobic stores will leave you ready to go 100 watts or more too hard for the first few minutes, for which you will pay dearly later on.  Do not go out too hard. Do not go out too hard!

The most important thing you can do is practice. If you have a 40k event coming up, practice 40k TTs a few times. If you have a half iron race coming up, practice a 56-mile bike ride, evenly paced with as few stops as possible, and then run afterward.  Pay attention to the wind, your speed, and how you feel to get an idea if you have paced it well.  An evenly paced time trial will generally feel very easy for the first few minutes.  As you get near the halfway point, things will start to be very hard; you will not believe that you can keep up the effort the whole time.  After halfway begins the ultimate suffering that you must fight through and never give up. A well-paced triathlon bike leg will be quite different. Ultimate suffering should be avoided and used on the run instead!

With practice you will get to know what it feels like to pace evenly.  You can even borrow a power meter or use the CompuTrainers upstairs at ATC to practice.  If you do own a power meter, occasionally practice with the display covered by tape, and then review how you did after the fact. This will leave you capable and confident on race day even if something goes wrong with your power meter.

Pacing the Hills

Hills will disrupt the simple plan of holding even power. The proper approach to maximize speed on hills is to go a little harder on the uphills and a little easier on the downhills. The most common mistake is for people to launch out of the saddle and throw an extra 100 or 200 watts on the uphills. This is too much; instead, raise power by 20 to 50 watts depending on how steep the hill is, and lower it by about that much on the downhills.  For longer distance triathlons, consider putting a cap on your power output about equal to your threshold or one-hour power to ensure you don't dip into anaerobic reserves.  If you don't have a power meter, just remember to raise your power on the uphills, but don't hammer like a mad man. On the downhills don't give up and coast; keep a little bit of effort on the pedals and shift as necessary to keep moving well.  Again, longer distance triathletes may want to consider coasting on any decent downhill to conserve energy for the run to come. Time trialists and short distance triathletes should keep pedaling whenever possible!

Pacing the Wind

Wind follows the same pattern as hills, but to a much lesser degree.  The harder the headwind, the higher you should raise the power, and the stronger the tailwind, the more you should reduce your effort. However, the optimum change is very small, only 2 to 4 watts in either direction.  This is so small of a difference that it can be hard to put into practice even with a power meter, so you can feel free to just ignore it and pace evenly for the most part.  Exceptions include cases where the tailwind on one part of the course will be so strong that you run out of gear. In extreme cases like that, you will want to push much harder into the headwind since you will get a forced rest with the tailwind.

Friday, July 26, 2013

Mavic CXR60
So aero they made a custom tire

by Jack Mott

For a little over a year, the new breed of Mavic wheels has been on the market in the form of the CXR 80, a deep wheel with a bunch of unique features that has proved to be an excellent performer. The CXR 80 was the TT wheel of choice for the Garmin-Sharp pro cycling team, and has also been ridden with success in the local bike racing scene, even in crits. However, it's available only as a tubular, and is deeper than some people are comfortable with. Now a medium-depth version of the CXR line is here, the CXR 60, and it comes in clincher too! The key features of the CXR line of wheels include:

New Aerodynamic Shape

Mavic's CXR line takes a unique approach to wheel shape. Unlike the rest of the industry (which somehow simultaneously adopted "U" shaped rims), Mavic uses a combination of custom tires and a "blade" that fills in the space between tire and wheel to have complete control of the entire wheel-tire shape. If Mavic's wind tunnel results are accurate, this gives them a sizeable aero advantage over other wheels.

Downsides to this approach include a reliance on Mavic's custom tire, which may or may not have great rolling resistance to go with its excellent shape. If the rolling resistance is not good, it can more than offset the aerodynamic advantage. This is of particular concern in the tubular versions of the wheel, as the rolling resistance is not very good with that tire. Tom Anhalt has measured the rolling resistance of the Mavic clincher tire and thankfully found it has excellent rolling resistance, details here.

The other downside is dealing with the blades. The CX01 blade snaps into the rim after you install the tire. The process is quite simple, but would be an extra step to deal with when changing flats on training rides. On the other hand, you don't have to use the blades on training rides; you can save them for race day. Additionally, you need to take care that the brake pads are adjusted properly, or they could grab the blade when you apply the brakes. There have been a few reports of blades coming undone during bike races, possibly due to contact with other bikes. They can then get wrapped up in your hub and end your race. The blades might best be saved for time trials and triathlons, where bike-to-bike contact is rare.

While Mavic literature insists that the blades are only compatible with the Mavic tire, during our testing we used it along with the Continental GP4000S and experienced no issues or wear on the sidewall. The aerodynamic fit seems to be excellent as well (click to zoom):

CX01 Blade Fit with Mavic Tire
CX01 Blade Fit with GP4000S Tire

However, given the good rolling resistance of the Mavic clincher tire you may want to stick with it, especially up front.

Exalith Braking Surface

The braking surface on the clincher version of these wheels is a special metal surface that Mavic calls Exalith 2. It has a directional texture, and is designed to work with a specific Mavic Exalith brake pad. The braking power and modulation on this is excellent, especially in the rain due to the texture feature. Our resident Cat 1 cyclist tester said she thought it felt better than her standard aluminum rims. While other racers get stressed out if there is rain in the forecast, you can remain calm and focus properly on your race, a nice advantage. The downside is the necessity of using the Mavic Exalith brake pad, which you may have to swap on and off if you use other wheels for training. In a pinch, other pads will work fine, but the Exalith surface seems to tear them up pretty quickly. You also must take care to orient your front wheel in the proper direction for optimum braking. We did test the braking with the wheel installed the wrong way around, however, and it still worked well.

The tubular version of the wheel uses a more traditional carbon braking surface.

Aero Tuned Hubs

The hubs on these wheels clearly have some aerodynamic thought put into them. The central section is as small as possible, and the flanges are also kept small and covered with smooth aero-shaped caps:

Real World Testing

Road testing revealed what we expected. Mavic wheels are very well built! There were no issues or drama under hard cornering or acceleration, and no flexing to cause the rear wheel to rub when pushing sickwatts up steep hills. We tested the wheels in a Cervelo S5 and a Litespeed C1 and found no clearance issues on either. Our resident Cat 1 cyclist Kat Hunter gave them a thumbs up, noting the exceptional braking performance. Meanwhile, our Cat 3/triathlete was able to decimate the local Strava scene in his neighborhood. Testing during windy days showed the wheels to be stable and predictable.

We noticed that the outer width of these wheels is quite wide, a bit wider that our HED Jets, in keeping with the current trend of sizing the wheel to match the width of 23mm tires. However, much of that width is used by the channel that you snap the CX01 blades into. The actual width of the rim from the tire's point of view is actually quite narrow. Rather than shaping the tire to fit the rim via extra wide bead hooks, Mavic uses the blade to provide a seamless tire to wheel transition. This design does make it a bit harder to work your tire onto the wheel. Below you can see the a blade, still snapped in place on the left, and the groove that the blades snap into on the right:

The construction of the clincher wheels is similar to HED Jets, with a carbon fairing attached to an aluminum rim. Mavic also applies a carbon fiber "cap" on top of the metal rim, however. The only exposed metal is the black Exalith braking surface and the black spokes.

Pricing and Availability

The CXR 60 will begin hitting Austin Tri-Cyclist (and other stores probably) in mid August.  Pricing info will be in soon. Each wheelset includes a bunch of nice extras:
  • BR601 quick releases
  • Rim tape
  • Wheelbags
  • Exalith brake pads
  • Valve extenders
  • Multifunction adjustment wrench