Parlee makes some of the nicest stock and custom carbon fiber frames on the market and the Parlee Manufacturer Profile has just been updated on our site for 2010.

Road Riders:  Be sure to check out the brand new Z5 road frames - one of our favorite stock frames for 2010 as it offers an incredible array of fit options, as well as the legendary Parlee quality and ride, at a price that is the same or less than many top quality frames from the big generic builders.   Oh, and did we mention that the Parlee Z5 is also incredibly light - our first units have been under 900 grams!

Triathletes and TT riders:  Be sure to check out the Stock TT, which is rapidly becoming one of our favorite stock aero frames for its great combination of fit options, high quality ride, top level manufacturing, NACA based aero profile, light weight and mechanical logic.

Guru Bicycles offers a great range of stock and customizable road and tri bicycles starting around $2500.  Guru offers unique options, like multiple finishes and up to ten colors as well as custom geometry, without extra charge on all their models.   We’ve updated the Guru Bicycle Manufacturer Profile in the Tech Center for 2010, including pictures and descriptions of the 2010 models.   New models like the next generation Crono 2.0 and the new ultralight road frame the Photon have also been added.     Visit the Guru Manufacturer Profile to read more about Guru as a company and be sure to scroll down to the bottom of the page where the new models for 2010 are profiled.

Visit our Tech Center Mechanical Services Page and scroll through the options to see videos on the following subjects are now posted:

• How to Change a Tire
• Bicycle Maintenance and Cleaning
• Basic Road Bike Brake Adjustments
• Derailleur Adjustment Fundamentals

Check them out!

Does Your Power Decline When Riding Indoors?

By Dean Phillips, Fit Werx

Many cyclists struggle to hold the same power output on a trainer that they maintain outside. Lack of motivation and scenery are often blamed, but the true answers are locked under the dust of your old physics textbooks from high school. I’ll save you the bad memories and explain…

The real reasons you struggle to hold power indoors are that there is less cooling effect and less flywheel effect indoors.

Less Cooling Effect

A cyclist cruising at 20mph outside experiences the equivalent of a big 20mph cooling fan continually blowing air over them. When you are riding a trainer, that massive 20mph headwind is gone. Without adequate cooling (just like any engine), your body temperature rises faster, your perceived effort goes up, and eventually your power output declines as you overheat. From a thermodynamics standpoint, this is an example of how forced convection from blowing air provides far more cooling than free convection in still air.

Like most cyclists riding indoors, I start my workouts with a warm-up that gradually builds power over time. My basement is around 55 degrees and I often found that once I reached about 200 watts of resistance I hop off the bike and turn the fan on. I wondered why this seemed to happen at around 200 watts and the answer became apparent when I revisited my HVAC design engineering days.

In HVAC design, when a building contained a room dedicated for heavy work, standards had us design that room at 55 degrees Fahrenheit with a cooling load designed to remove 2000 BTU/hr, or 586 watts, of waste heat per person. Studies show that a cyclist has a metabolic efficiency of roughly 25% and, based on this, we can calculate how much power goes to the pedals and how much is lost as heat by using the formula 0.25 = W / (Q+W), where W is pedaling watts and Q is waste heat to the surroundings. Plug in 586 watts for Q, and W = 195 pedaling watts and the answer is 586/195 ≈ 3. Cyclists release 3 watts of waste heat for every 1 watt that’s applied to the pedals. This means that a rider pedaling at 195 watts can usually do so in a 55 degree ambient temperature room without an overheating problem, but if they apply additional watts, they will likely start to overheat.

Doesn’t the rider’s size have something to do with this? Yes and no. Overheating has more to do with the absolute power you ride at, and less to do with the power relative to your Functional Threshold Power (FTP). In other words, regardless of your size and weight, hitting 195 watts in a 55 degree room is what matters. A larger stronger cyclist riding at 16 mph and producing 195 watts may start overheating during warm-up, while a smaller cyclist may be going 18mph at 160 watts and may never overheat in the 55 degree room as they never cross that magic 195 watt threshold.

Overheating occurs when riding at a high enough power level for a long enough time overtaxes the body’s cooling system. The most challenging indoor cycling workouts are those that stress both power and duration - the “double whammy” of overheating. Long intervals such as 2×20 or 4×10 minute intervals at FTP are common staples for cyclists and triathletes, but these are among the toughest to perform indoors without suffering miserably and/or experiencing power loss. A power loss compared to riding these intervals outdoors at the same wattage is inevitable without substantial cooling assistance.

Shorter higher intensity intervals are more reasonable to perform – such as 5 x 2 minute VO2 max intervals. While the intensity is higher and the effort is hard, there isn’t enough time for lack of cooling to negatively impact results the way it does in longer intervals. Longer lower intensity workouts are also less prone to power loss.

Based on this, some potential solutions to the increased heating demands of riding indoors are as follows:

1. Keep the room as cool as possible, preferably under 60 degrees. You likely will not win any points with your family or roommate(s) by opening the windows in the living room in January, so consider moving training to a cool basement. Remember, training must be tolerated by those around us first, and comfortable conditions come second. J
2. Use a large fan for cooling; the more air it blows across your body the better. You can increase the fan speed for higher intensity workouts.
3. When all else fails, restructure your indoor workouts into shorter higher intensity intervals and longer easier rides.

Flywheel Effect

When you stop pedaling on a flat road outside, you can coast up to a minute before coming to a complete stop, but when you stop pedaling on your indoor trainer, your rear wheel stops spinning in seconds. Why? Outside you have the momentum of the bike, rider, and spinning wheels; that’s a lot of momentum working in your favor. An indoor trainer replicates some of this momentum through the flywheel attached to the resistance unit - the larger the flywheel the longer it can hold its momentum. While a larger flywheel helps slow the deceleration of the rear wheel, it does not replicate the momentum you experience outdoors and thus you have to work harder to maintain momentum on a stationary trainer.

Because of the flywheel effect, the way you apply force throughout the pedal stroke also changes compared to riding outdoors. Outdoors, riding on flat terrain, we may think we’re pedaling in perfect circles at 90rpm from all those one-legged drills we did the prior winter, but the reality is the pedal force of the down stroke leg helps move the recovering leg through the back and top of the stroke and into position for the next down stroke. However, when you start to climb a hill, your pedaling becomes more similar to what happens on a trainer - if you ease off the pedals, you lose momentum quickly. Your cadence typically drops climbing hills or riding a trainer as smaller hip flexor muscles prefer to have more time to activate as they are lifting on the upstroke and pushing forward over the top of the pedal stroke. It’s quite common for a cyclist’s cadence to drop 20-30 rpm when they’re climbing a hill and riding at a lower cadence on an indoor trainer makes the effort feel more in line with that same perceived effort outside.

Try these solutions to give yourself more wheel speed and a larger “flywheel effect” riding indoors:

1. Only use enough press-on force on the roller drum to prevent the tire from slipping.
2. Use a trainer with a larger/heavier flywheel. Some trainers, like the Kinetic by Kurt, offer optional super heavy flywheel attachments.
3. Use a lower rolling resistance tire on the trainer. Many cyclists use big thick tires that wear a long time on the trainer, but those tires typically come with a rolling resistance penalty and rolling resistance is amplified on the trainer.
4. Take on the challenge of learning to ride rollers. The benefit of two wheels spinning instead of one improves road-like feel. If you can’t get the resistance you want on rollers, try higher resistance tires, smaller diameter roller drums, or - my favorite – letting air from the tires until you run out of gears right at the interval power you are targeting.

Once you’ve taken measures to improve flywheel effect riding indoors, the best solution is simply allowing your cadence to drop to a level that feels comfortable. Depending on the stationary trainer, I’ll let my cadence drop 5-15 rpm riding indoors. If you work with a coach, send them a link to this article and beg to ride at 85 rpm instead of 95 rpm for the workout you’ve been prescribed.

So there you have it. The keys to riding indoors at the same power level and perceived effort as you can ride at outside are: 1) Riding in a cool environment. 2) Find the largest fan possible. 3) Riding at a lower cadence to make up for the lesser flywheel effect.

Happy indoor training! J

DP

Dean Phillips is a co-owner of Fit Werx² in Peabody, MA. Dean frequently writes tech articles for Begginertriathlete.com and is humble enough that he would likely never tell you (so we’ll tell you for him) just how fast he is on a bike. Dean holds multiple TT course records in New England, having broken records previously held by some of America’s best pro cyclists and he set these while being a father of three children and owning his own business. Dean knows speed and how to get the most out of his training time.

originally published November 2009/ Copyright © 2009

Since the August 2009 “Tech Support” on bearings was published, I’ve been asked some good follow up questions about choosing bearings and bearing ratings.

Question 1) “I’m not that technical.  What is the biggest thing to focus on when choosing a replacement bearing?”

Look for quality and reputation over material and ratings.  You get what you pay for and just being ceramic, like just being carbon fiber, does not always make something better.  A high quality steel bearing made with top quality materials, grain structure and race polishing will perform better than a basic ceramic (even if the ceramic is “rated” higher) bearing.  If a company like Ceramic Speed (the arguable inventors of ceramic bearings for bicycles) or Zipp (likely the earliest to offer ceramic options from the factory) is selling a high quality bearing for a certain price, you are not going to find that same quality bearing for significantly less money.  Even if two bearings are rated the same on paper, if one bearing costs less, the lower priced manufacturer cut costs in the quality and refinement of the materials.  These are things you can’t see or feel by looking at or spinning a bearing in your hand, but that are significant in how well a bearing works and lasts when it is actually being ridden under load.

Question 2) “Why do some companies list both an ABEC rating and a millions of an inch Grade rating?”

In the August article, I misstated that ABEC rates both ball and race tolerances and that millions of an inch Grade primarily applies to loose ball bearings only.  “Radial Run Out” in regards to ABEC ratings is not the roundness of the balls; it is actually a measurement of the consistency of the roundness of the groove in the race that the balls roll. ABEC standards only apply to race symmetry and tolerances and do not consider the roundness of the balls.  Grade, on the other hand, refers to ball roundness in either a loose or cartridge bearing and does not consider the race tolerances. Companies list both the ABEC (race tolerances) rating and Grade (ball roundness) because both ratings are important reflections of the tolerances in the bearing system as a whole.

Question 3)  “Why are some steel bearings more expensive than some ceramic bearings of a higher Grade?”

Bearing Grade is not what matters most.  Bearing Grade is universal across materials, so one Grade 10, regardless of whether the balls are ceramic, steel or silly putty, has the exact same tolerances/roundness as another Grade 10.

True bearing quality and performance comes down to the grain structure, polish and refinement of the materials used in the fabrication.  You can have very round bearings and races, but if they do not offer appropriate material integrity and finish for each other, they will not work ideally together.  For example, imagine you had two bearing systems with identical tolerances (Grade and ABEC ratings) and identical ceramic balls, however, one had races made of silly putty and the other steel.  When they are unweighted and properly lubricated, both bearings might spin well in your hand, but what happens when you apply weight?  The silly putty races deform, bind and grind to a halt immediately, while the steel still spins.

Now, let’s take this same concept of harder balls and softer races and apply it to common ceramic hybrid bearing construction.  If ultra hard Grade 5 ceramic balls are placed in super hard, fine grained ABEC 5 steel races with proper lubrication, they will resist binding, pitting and deformation and will roll smooth and fast together for a long time.  However, if you take these same Grade 5 ceramic balls and place them into ABEC 5 steel races that are not as fine grained and highly polished (softer), the substantially harder ceramic balls can wear the races much quicker.  The race will pit and the softer race can even crack under impact loading (actual riding).  The same thing can happen in full ceramic or full steel construction.  In fact, some manufacturers will not even use a full ceramic cartridge bearing at this time as they have not found a ceramic cartridge where the races are strong enough to meet their standards.

In addition to making sure the balls and the races are polished and hard enough to wear well together, the quality and tolerances of the seal design, the volume of grease in the bearing and its formula, and the purity and cleanliness of the assembly process matters as well.  Just like with carbon fiber construction, keep in mind that the easiest way to save money when building bearings is to spend less time refining the materials and assembly.

If you are choosing between a $25 Grade 10/ABEC 5 steel bearing offered by a manufacturer known for high quality engineering, materials and attention to detail or a $20 Grade 5/ABEC 5 ceramic hybrid from a supplier who sources their bearings from an unknown factory based in a country that may not recognize ABEC standards, the steel bearing will likely offer you higher performance.  As stated previously, look at quality and reputation over material and ratings when choosing replacement bearings or considering an upgrade.

Question 4) “My bearings are worn out.  Should I upgrade to ceramic bearings?”

On wheels, the answer is “Maybe”.  High quality ceramic bearings in combination with tight tolerances hubs (DT, Zipp…) are a great combination.  However, if you have high precision hubs and are wanting to keep bearing costs under $100 a cartridge, consider buying the very best quality steel cartridge bearing you can from a reputable manufacturer, as they will likely work better than a lower quality ceramic.  If your wheels do not have high precision hubs, consider saving yourself some money and going with the best Grade and quality steel bearings you can.  Less aligned hub shells actually require more bearing play to roll smoothly in the long-term and a high quality Grade 10-25 steel bearing will not only save money, but might work better and last longer than a tighter tolerance ceramic that may not be aligned in the hub shell as well as its tolerances require.

Partly because they use bigger bearings than hubs, just about all bottom brackets benefit from high grade steel or ceramic bearing upgrades.  Shimano, FSA and SRAM cranks (amongst others) have a fair amount of seal and bearing friction that is noticeably reduced with a high quality bearing upgrade in ceramic (Ceramic Speed, FSA…) or steel (Chris King, Hawk Racing…).  Because bottom brackets use bigger bearings than hubs, the tolerances and manufacturing precision don’t need to be as precise to gain the same performance.  Note that no matter how high quality the bearings, if they are not mounted flush, they are going to be held back and could wear prematurely.   Very few frames come from the factory with well faced bottom bracket shells, so make sure the shell is faced by a good technician before installation.

Ride hard and smart.

Ian

Ian Buchanan is co-owner of Fit Werx.  Fit Werx has locations in Waitsfield, VT and Peabody, MA and offers cycling and triathlon products, specialty bicycle fitting and analysis services, consultation, and technology research.  Fit Werx can be reached in VT at (802)496-7570, in MA at (978)532-7348 or through the Web at www.fitwerx.com.

originally published August 2009/ Copyright © 2009

In the April 2009 issue of Triathlete, in the Tech Support column, there was an article that mentioned ceramic (hybrid) bearings and recommended a Grade 3 bearing or better.  From the Internet, I found that some manufacturers say Grade 5 bearings are the best to get (for cycling applications), while others say Grade 3 is the best.  If Grade 3 bearings are the best, does that mean that the Grade 5 Ceramic bearings used in my FSA bottom bracket and HED FR wheels are no better than a steel bearing?  Thank you.

Jack, Louisiana

Dear Jack,

ABEC Grade 5 bearings are actually better than Grade 3 and Grade 3 was the minimum grade recommended in the article, so the bearings you have are some of the highest grade readily available in the cycling industry. The higher the ABEC grade of a bearing, the more symmetrical and tighter the tolerances of the rings (races) that hold the balls.  Bearing ratings can be confusing and they only tell part of the story, thus some additional information may help.

Bearings in the cycling industry are rated by their ABEC grade and/or by their overall roundness in millions of an inch.  Cartridge bearings are the most common type of bearings on bicycles and most companies usually rate by their ABEC grade over their millions of an inch grade.  For this reason, I’ll discuss ABEC ratings first.

ABEC Rating: The “Annular Bearing Manufacturers Association” has a committee that sets standards for bearing precision called the “Annular Bearing Engineers Committee” - “ABEC”.

Cartridge bearings are the most common bearing type in the cycling industry.  A “cartridge bearing” means that the balls, seals, grease and the internal and external races are all built into a single cartridge bearing unit that is usually press fit into the application.  ABEC grading considers the precision of the rings (races) that the bearings roll on, but not the precision of the balls.  The ABEC scale rates bearing precision on four levels: 1, 3, 5 and 7.

ABEC 1 is the lowest level of bearing that is considered “Precision”.  ABEC 1 bearings are specified on three variables:

1. Bore - The Inside Diameter of the bearing - also measured as the size of the shaft (inner cone) that the bearings revolve around.
2. Radial Run Out - The roundness of the actual races.
3. Ring Width Variation - The consistency of the width between the inner and outer bearing rings.  The more consistent the ring width around the entire bearing, the smoother the balls can roll between the rings and the higher the precision.

ABEC 3 bearings are rated on the same three dimensions as ABEC 1, although at tighter tolerances.  For example, an ABEC 1 bearing will have .0003mm of Radial Run Out (roundness variation), while an ABEC 3 has only .0002mm of variation.

ABEC 5 bearings not only have tighter tolerances on the three core variables above, but they must also adhere to set standards on additional dimensional items within the bearing as established by ABEC.  These additional tolerances provide greater precision and lower rolling resistance. The differences between a Grade 3 and 5 bearing for cycling are noticeable and many companies use Grade 5 for this reason.  Grade 7 bearings tighten the tolerances further still.

It is important to note that the ABEC rating system only applies to the tolerances that ABEC sets as standards and does not consider some other important variables that can affect bearing performance and durability.  Ball tolerances, materials, grain structure,  grease, seals and manufacturing environment are examples of things that are not taken into account by the ABEC ratings.

Millions of an Inch Rating: You may also see bearings listed anywhere from Grade 2 to Grade 1000 in the cycling industry.  These parameters simply refer to how round the balls are in millions of an inch.  In this rating system, the lower the number the better the quality of the bearing and the harder and better finished the bearing.  For example, a Grade 25 is round to 25/1,000,000″, while a Grade 1000 is round only to 1000/1,000,000″.  For perspective, loose bearings found in a Shimano Dura Ace hub, would often be Grade 25.

So, what do you need to know when you are selecting bearings for cycling?

If you are looking at loose bearings graded between 2 and 1000, get the lowest number available for the application.  The price difference is minimal between a Grade 25 and a Grade 300 or 1000 and the tighter tolerances and roundness of the bearings makes a notable difference in any rolling application (like hubs).

If you are looking at ABEC graded bearings, a Grade 1 bearing does not have very tight tolerances and performance will be limited.  A Grade 3 is a significant step up from Grade 1, while a Grade 5 is where the performance “sweet spot” is located for cycling.  This is why most ceramic and ceramic hybrid bearings for bicycles are Grade 5.  Grade 7 bearings offer only a small gain in tolerances compared to Grade 5. The cost of a Grade 7 bearing can be up to ten times the cost of a Grade 5 bearing and would really only show further benefit in very high RPM mechanical applications (well beyond what can be achieved on a bicycle).

As mentioned above, because ABEC bearing grade only reflects precision of dimensions, you need to be careful that you still get what you want in other important aspects of bearing performance.  For example, ABEC ratings don’t take materials or hardness into account and thus you can have an ABEC Grade 5 steel bearing, Grade 5 Ceramic or Grade 5 “hybrid” bearing.

Full ceramic bearings use ceramic balls and ceramic rings (races).  Ceramic is significantly harder than steel, requires less lubrication and is lighter, so a top quality Ceramic bearing will offer less rolling resistance, greater durability and lower weight than a steel bearing of the same grade.  Hybrid bearings are the most common type of “ceramic” bearings in the cycling industry.   In a “Hybrid” bearing you will find ceramic balls rolling on steel races.  So, look at the big picture and realize that if you want the full benefits of a Ceramic bearing system, you need to look beyond the grade and at the materials, the quality, and the fabrication of the bearing as well.

Hopefully this helps you select the right bearing for your needs and high quality Ceramic bearing technology is well worth considering if you are trying to maximize your performance and are upgrading a high precision component.

Ride hard and smart.

Ian

Thanks to Max Ralph at FSA for helping with this article.

Ian Buchanan is co-owner of Fit Werx.  Fit Werx has locations in Waitsfield, VT and Peabody, MA and offers cycling and triathlon products, specialty bicycle fitting and analysis services, consultation, and technology research.  Fit Werx can be reached in VT at (802)496-7570, in MA at (978)532-7348 or through the Web at www.fitwerx.com.

originally published July 2009/ Copyright © 2009

Dear Tech Support,

I have had a road bike for a few years, but am new to triathlon.  At the end of last season I added aerobars to make my bike more triathlon specific.  They have not been very comfortable though and my friends say I look “awkward” when riding in them.   I was fit to the bike when I bought it, so what am I missing?     Caitlin V., via e-mail

Dear Caitlin,

Many riders add clip-on aerobars to their road bike to make the bike work better for triathlon.  However, clipping aerobars onto your road bike, without making other changes in positioning and components, is like putting a cook top in your living room and then expecting it to function like your kitchen - additional changes are needed for it to work well.  Along with adding aerobars, some other fundamental changes to your riding position and equipment on your road bike can help you achieve your potential.

Positioning: Aerobars alone do not make a bike triathlon specific - riding position does.  What I mean by this is that no matter how many triathlon oriented components you put on your road bike, it is not going to be set-up well for triathlon until your bike is fit specifically for your needs when riding in the aerobars.  Your bike fitter may have done a good job with your road position when you bought your bike, but I’m sure she built your position to work best without aerobars.  Getting refit specifically for an aerobar based triathlon position by a fitter who is skilled and well-educated in cycling biomechanics for triathlon is where you should start.  With proper set-up and a basic understanding of aerobar riding technique, the vast majority of riders should find riding in the aerobars one of their most comfortable hand positions.

Components: Once you have been fit specifically for triathlon cycling, your current road bike can often be converted to your new aerobar position with a few component changes.  Common positioning adjustments include the seat coming forward (to maintain an open hip angle in the new lower handlebar position and help encourage an easier muscle transition to the run) and the handlebars being set-up lower and with a shorter reach (to make sure your body is as skeletally supported as possible in a more aero and forward riding position).  Components that will often need to be changed on your road bike to allow for such positioning changes include the seatpost, aerobars and stem.

• Seatposts: Depending on your riding position and the seat tube angle of your road frame, most riders will need a seatpost that allows the seat angle on their road bike to come forward 2-6 degrees.  If you need to steepen your road frame just a couple degrees a Thomson set-back seatpost used in reverse of its original intent can work quite well.  If you need a major change in seat angle, Profile Design’s Fast Forward seatpost, available in an alloy or carbon version, allows over five degrees of forward angle (thus allowing a road frame with a 73 degree seat tube angle to be capable of at least a 78 degree seat angle).  Note that the hardware on the Fast Forward is not compatible with some saddles (many Selle Italia models built in the past five years, for example), so be sure to check compatibility.

• Aerobars: Aerobars all fit different and you should understand how any aerobar you are considering relates to your riding position and frame geometry before purchasing them (Tech Support, April 2007 covers fit differences between some popular clip-on bars).   Highly adjustable clip-on aerobars, like the Profile CarbonStryke, are often some of the best for adapting a road bike to a triathlon position.

• Stem: When selecting a stem, do not sacrifice positioning and safety for aesthetics and weight.  Aerobars can put a lot more leverage on the stem clamp than a standard road bar without aerobars, so make sure you use a secure and strong stem.  If one is available in an appropriate length and angle, 4-bolt stems (like Ritchey’s offerings) are light, strong and secure.

• Optional Items: Additional triathlon specific component changes on your road bike can further enhance speed and performance by allowing you to stay in your aerobars longer and in greater comfort.   Bar-end shift levers allow you to shift without leaving your aerobars and can be used with flat pursuit bars to reduce weight and aerodynamic drag.  A triathlon specific saddle can help address the increase in forward saddle pressure that is common with shifting rider weight forward and lower.

Once changes have been made to the bike, you are ready to start riding in the new position.  Remember that anytime you make positioning changes it is important to allow your muscles a chance to adapt to the demands of a new position, so start slowly and build into the changes.

Once you have converted your road bike, you will be well on your way to maximizing your potential on the bike for triathlon.   However, there are two reasons I would encourage you to still start saving your dollars for a triathlon specific bike down the road.

1)     Road bike riding, without aerobars, can make you a better cyclist.  Many of the most accomplished cyclists in triathlon log the majority of their training miles on a bike that is not their tri bike; we highly encourage triathletes to have a road bike, without aerobars, available as the potential training and technique benefits are substantial.

2)     Road bikes are designed to handle best with the rider’s weight distribution biased slightly to the rear of the bike.  A dedicated aero position, on the other hand, can have over 60% of the rider’s mass biased towards the front of the bike. Triathlon specific bikes are designed to take this more forward weight distribution into account and handle as best as possible when the rider is in the aerobars.

When the time is right for that new triathlon bike, the information from the triathlon specific fitting you did when converting your road bike can be used to help you find the bikes that match the needs of your body best.   A list of dealers who approach fit from a “Rider First” perspective and product selection from a “Fit First” perspective can be found at www.masterbikefitters.com.

Ride hard and train smart.

Ian

Ian Buchanan is co-owner of Fit Werx.  Fit Werx has locations in Waitsfield, VT and Peabody, MA and offers cycling and triathlon products, specialty bicycle fitting and analysis services, consultation, and technology research.  Fit Werx can be reached in VT at (802)496-7570, in MA at (978)532-7348 or through the Web at www.fitwerx.com.

A few weeks back Dean, Geoff and Marty traveled to the CCNS Performance Center Wind Tunnel for some equipment testing.  We had a great session and we thought it was worth sharing our experience and what the wind tunnel can offer.

From past experience we know that the wind tunnel is not a place to be redefining your riding position - it is a place for subtle refinement and equipment testing.   We have seen some people who have gone through wind tunnel testing at some facilities and the session focused so much on aerodynamics that the position they arrived at was not at all maintainable or comfortable for the rider outdoors.  The results were a very fast looking position, but the rider actually compromising power and comfort so much that they were actually slower.  To get the best results from the wind tunnel, you should have a comprehensive bike fit first to establish a solid and biomechanically functional position and then you should spend your time testing minor changes in position and testing different equipment (like helmets, hand angle…).   This is what we did.

The Tunnel:

CCNS uses low air speed around 14mph which reportedly gives the same aerodynamic drag coefficient (CdA) results as at race speed. CdA is the product of a rider’s frontal area (A) and a coefficient of drag (Cd). The lower the CdA, the faster you’ll go for a given power output. CdA is generally a fixed value independent of rider speed. Our testing was done without pedaling or wheels moving. They have the capability of testing with rider pedaling, but we preferred the accuracy and precision of the rider sitting still as we were not going to redefine our position and wanted to focus on non-dynamic positioning changes and equipment differences.  Knowing this ahead of time we chose to focus on testing equipment and position changes that shouldn’t be effected by pedaling mechanics. We didn’t bother to venture into wheel testing, frame water bottle placement, and anything else that’s more dependent on moving rider/frame/wheel interaction.

Testing Protocol:

Dean and Marty tested about six positions each during the course of the sessions at a 5 degree yaw angle. Based on Dean’s past testing and representative real world wind conditions he sees on most TT courses the 5 degree yaw angle best represented the conditions we were seeking. Each position test included 4 separate 30-second runs, and the CdAs from each of those 4 runs were averaged to give you the final CdA for that position. Accuracy and precision were taken seriously as the wind tunnel drag measuring equipment was checked and calibrated before each run.

Athlete’s Starting Equipment and Kit:

Dean: Cervelo P4, HED Integrated aero bars, long sleeve Champion Systems speed suit, aero booties, Louis Garneau Rocket TT helmet, Zipp ZedTech 1080 front and rear 900 disk, no hydration on the bike except the integrated P4 water bottle.

Marty: Parlee TT bike, Zipp Integrated Vuka Bar, Champion Systems Tri Top and Tri bottom, Louis Garneau Rocket TT helmet, Zipp 808 front and rear 900 disk, no hydration on the bike.

Testing and Results:

Over the years Dean has refined his position and equipment selection through hundreds of hours of field testing. As record holder of numerous local time trials and triathlon bike courses, his testing results and very aerodynamic position have propelled him to many impressive finishes. If any significant improvement was gained as a result of this testing session we would be happy.

Starting Position:

Dean: Reported CdA values tend to vary from wind tunnel to wind tunnel due to a variety of factors we won’t get into regarding air boundary layer control, air speed measurement, and drag measuring technology. CdA is also impacted by yaw angle, whether or not the rider is pedaling and wheels rotating. For the purpose of this visit it’s not the exact CdA value that matters, but the relative changes to this value that matter. Dean tested his CdA in field testing in the 0.22-0.23 range out of the wind tunnel. The first run resulted in a CdA of 0.240, so we felt we were in range.

Marty: Current CdA had not been accurately determined with field testing, but we’ve estimated his CdA at 0.250 based on race results, and training rides given his body size, equipment, and power output. Starting position resulted in a 0.261 CdA.

Position #2:

Dean:

Helmet Change: Dean switched from the LG Rocket to the LG Superleggera. The Superleggera is the newest version of the Rocket helmet, but has dimples over the top and larger vents in the front. The best TT helmet for a rider tends to be very individual and this was certainly the case for Dean.The Superleggera was clearly faster than the Rocket for him so he kept this on for the rest of the tests: Result = Faster: CdA 0.236

Marty:

Drop: We moved Marty 2 cm lower which resulted in the same 0.261 CdA. If anything the lower position could have proved less comfortable or resulted in some power loss from closing him off too much at the top of the pedal stroke. Since there weren’t any benefits we moved him back to the starting position and moved on to Helmets.

Position #3:

Dean:

Drop: We dropped the front end 2cm lower than his current field tested position. The result was the same CdA, so there was no reason to run any more drop than he currently had. Dean had already tested this in the field and did not see a benefit, but wanted to try it under wind tunnel conditions. Result = Same: CdA 0.236

Marty:

LAS Crono TT Helmet: In Marty’s case the LAS Crono proved slightly faster than the LG Rocket.Equipment can be very individual and this proved the case here. Result = Faster: CdA 0.256

Position #4:

Dean:

Drop again: We raised the front end 2cm higher than the baseline (4cm higher than position #3). We only did 2 data runs because this position was clearly slower, so we didn’t waste any more time. Our conclusion was that he must have passed a critical point where his head was just getting too high in the wind and drag went up quickly. Result = Slower: CdA 0.260

Marty:

Spiuk Kronos Time Trial Helmet: Big gains made with the Kronos. Marty’s starting CdA was 0.261 and the Kronos brought this down to 0.246. Significant savings on paper!

Position #5:

Dean:

Horizontal Water Bottle mounted between the aerobars:We went back to the baseline drop and then added the water bottle between his forearms. Dean ran this system during Timberman and while it felt different he wanted to know the actual difference.

Cervelo tested something similar in the wind tunnel and said it reduced drag, but this definitely depends on the individual setup, and likely yaw angle as well. Result = Slightly slower than fastest run: CdA. 0.239

Marty:

Reach: Marty realized during races that when he held the end of his aero extensions that his head dropped and he felt just as relaxed and powerful. We’d experimented with this in the shop and noticed not only did his head get lower, but his shoulders narrowed a bit with the longer reach. The wind tunnel confirmed our suspicions as the resulting drag reduction was notable.   Marty’s CdA dropped all the way to 0.237 and we knew that Marty had refined his riding technique enough in the past few years to the point that he could maintain this longer position comfortably.

Position #6:

Dean:

Aerobar Angle - We tilted Dean’s Hed aerobars up just slightly - about 5 degrees. He’d tested this in the field without seeing any gains, but had made some other position changes since then. Dean noticed that a slight amount of tilt leveled off the tops of his forearms, lowered his head and shoulders slightly, and was more comfortable. As he settled into the position he figured that if he got the same CdA then he would run this position since it was more comfortable. We were all pretty excited during the first run because there was quite a reduction in drag. After 4 runs including a re-check of the calibration we confirmed a faster and more comfortable position. Result = Fastest: CdA 0.229

Marty:

We tested his aero pads closer together, and it actually increased his CdA to 0.244. We went back to his original pad width and tried tilting the aerobar extensions up 5 degrees just like Dean’s. The upward extension tilt actually increased Marty’s CdA, despite helping Dean lower his, which supports our experiences that aerobar tilt/angle gains tend to be individual.

Final Analysis:

As bike fitting experts we expected our starting positions to be fast, but looked forward to searching out any potential gains in equipment and fine tuning our positions. In Dean’s case the only two things that helped make him faster were the helmet change and the aerobar extension tilt. In Marty’s case a different helmet change and slightly longer reach made significant improvements.

Dean lowered his CdA from 0.240 to 0.229 which at his race power and speed is worth about 17 seconds in a 10-mile TT, 27 seconds in a 13-mile sprint bike leg, and about 1:40 in a typical HIM 56-mile bike leg.

Marty lowered his CdA from 0.261 to 0.237 which at his race power and speed is worth about 46 seconds in a 10-mile TT, 57 seconds in a 13-mile sprint bike leg, and about 4:16 in a HIM 56-mile bike leg.

Take Home Message:

The trip to the tunnel was a blast and the sessions are best used to refine your position and/or look into equipment options.  We are excited to try out the tunnel results in 2010 and see how well they hold up in the real world.

Like previous trips to a wind tunnel, our recommendation that the athlete should go through the bike fitting process before heading to the wind tunnel was reinforced.   Wind tunnel time goes by quickly and it is not cheap.    It does not make any sense to use valuable tunnel time finding gains that are easily identified outside of the tunnel in the bike fitting process while also establishing the rider’s individual biomechanical range that they need to stay in if they are going to maintain power and comfort.  By getting fit first, the athlete will be able to use most of his/her time refining details that can only be accomplished in the wind tunnel or carefully controlled field testing.  If you have any questions or would like additional information on our fitting services please contact us directly.

Disclaimer: Our testing session at this wind tunnel was done at only one yaw angle, there wasn’t any pedaling, and the wheels weren’t turning. Actual CdA values for riders pedaling on moving bikes in a range of real world wind conditions may be slightly different but will be in the same ballpark. We are looking forward to racing in our new positions next season, and of course field testing things against them in our continuous quest to find faster positions and equipment for the athletes that work with us!

Many rider’s and triathletes stretch and strength train as part of their fitness, but how many of us actually do the right stretches and weights for cycling and triathlon?   If you want to get the most out of your training this winter, check out these how-to demonstrations designed specifically for cyclists by the lead biomechanist at Kinetic Loop Training.   These and other training, health and coaching resources can be found “Technique and Training” section of our Tech Center.