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Active Expert: Bruce Hildenbrand

4 Posts tagged with the power_tap tag

I have written about the use of power meters several times in the past year. I still ride with one and am still finding ways that it helps my riding. As I said before, I don't race anymore so I am not looking for something to either help me with my intervals or to analyze my performance on race day. What I am looking for is something, at a much higher level, to tell me the difficulty of a ride I am doing and how I am performing.


Again, I am looking something at a very high level. I don't really do "structured" training, per se. I figure out a ride of a certain length with a certain amount of climbing and I go and do it. So, I am not looking at my sustained power up a specific climb. I am looking for a more general measure of how I am riding on that day. But, for the "how am I riding that day" to have some meaning, I also need to figure out how hard the ride was from a terrain/environment perspective.


I think I have found a good indicator of both how I am riding and how difficult the ride actually was. My Power Tap power meter has a setting which displays the total energy expended on a ride, expressed in kilojoules(kj). On the flats, the harder I go, the more energy I expend. Unfortunately, on climbs below about 12mph climbing speed, you expend the same amount of energy for a particular climb regardless of how fast you go. This is a bit of a digression, I will get back to that later.


What I do after a ride is to divide the total energy expenditure by the number of miles ridden. Today, I expended 3186 kj on an 86-mile ride giving an rating of 37kj/mile. This was a hilly ride, my total climbing was 7500 feet. Two days ago I burned 3000kj for 80 miles for 37.5kj/mile. Again this was a hilly ride with over 6500' of climbing. Last Saturday, I burned 4000kj in a 110-mile ride for 36kj/mile. This was another hilly ride with 7500 feet of climbing.


So, my empirical data seems to indicate that somewhere in the neighborhood of 37kj/mi is a good number for me on a hilly ride. As a bit of comparison, on my flatter rides, I get somewhere around 20-25kj/mi.


Unfortunately, this type of measurement is still not ideal. Clearly, for me, I burn a lot more energy going uphill than on the flats. But, because you can't really change the energy expenditure by going faster on a climb, this number is more an indication of two things. First, it is a good indicator of the amount of climbing you have done. Secondly, it is also an indicator of how fast you go on the flats. For a given ride, if I go harder on the flats, I will expend more energy. Well, duh?


So, if you want to compare how you were riding while doing a particular ride, going faster, or slower, on the flats and flatter sections affects the kj/mile. But, when comparing different rides, the more climbing, the more energy expenditure per mile, unless of course you can ride on the flats at the same watts you put out on the climbs.


Everything here is still a work in progress. Stay tuned for more.



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Power to the People

Posted by Bruce Hildenbrand Apr 14, 2009

I have been using my Saris Power Tap on my bike for the past several months and have learned a few things about training with a power meter which seemed good to share with my fellow cyclists.


As I said in my first posting when I had completed just a few rides with the Power Tap, I am not a rider who does a lot of structured workouts.  Yes, I do average over 300 miles a week, but all of my riding is what most would call long tempo rides.  I don't do intervals, but I will kick it a bit on the climbs.


So, I wasn't looking for a power meter to help me with my intervals. What I was looking for was something which could help me gage how to read what my body was telling me. By that, I mean it is reassuring to see that when my body is screaming pain, I am pushing 350+ watts up a climb. That says to me that my pain meter is pretty accurate.  If my body was screaming pain while I was generating 200 watts then something would be wrong.


Another thing that was really interesting to discover is how my body can mask a drop in effort after a hard effort.  By that I mean that when I am cranking up a hill at 350 watts, when the hill drops from say 8% to 4%, the number of watts I am generating in the same gear can drop as much as 100 watts.  However, there is a definite lag in how my body feels.  It takes me 30 seconds to a minute to re-adjust to the lower effort.  For those first 30 seconds to a minute, it feels like I am going just as hard at 4% as I was at 8%.


Sometimes my bulb doesn't shine too brightly. It took me a bit of cognitive activity to realize that, environmental conditions aside, it takes the same amount of energy to climb a hill whether you go fast or slow. It is just the law of physics. It takes a known amount of energy to raise a known weight a known height.Thank you Mr. Gravity. So, if you go harder, it just means that you will get to the top faster.


One thing that I really like about the Power Tap is that it has a setting for total energy expended during a ride. This is given in units of kilojoules, but in talking with noted power expert Dr. Allen Lim, you can convert kilojoules directly to calories because the human body is such an inefficient engine.


I live in a somewhat hilly area, Silicon Valley, so most of my rides have between 75 and 100 feet of climbing for every mile ridden. What I am finding is that I burn about 500-550 calories per hour of riding so in a typical seven hour ride in the Santa Cruz Mountains I burn about 4000 calories.


Granted, power meters are a bit on the expensive side and some of them require a new crank or bottom bracket, but I think there are some definite, tangible benefits.  I get a bit depressed when I am going hard at the end of a long ride and I can't seem to keep the power over 300 watts on that last long climb. But a couple of weeks ago, I had a big tailwind on one of my hillier rides.  I was going well up the climbs and would have attributed it to the tailwind, but my Power Tap told me that I was still generating good wattage meaning that I was still working hard and not just getting a push from behind.



924 Views 0 Comments Permalink Tags: bruce_hildenbrand, power_tap, power_meter, dr_allen_lim, mr_gravity

I just got a Power Tap power meter and things will never be the same when I ride my bike. In case you were worried, I am talking a positive change in my cycling. After only three rides, the Power Tap has opened my eyes to a lot of things and has answered a lot of questions as well. As I said, things will never be the same.


Back in my heavy racing days I did intervals, religiously, and based on my results, they paid off. Clearly a power meter can tell you a lot and help your training in a major way. I don't do structured workouts anymore, but the power meter has definitely helped my riding nonetheless.


For example, it gives me a good indication of my overall fitness. While my performance numbers match Lance Armstrong's on the right side of the decimal point, I am not looking to go toe-to-toe with the Texas Tornado on the left side. What I am looking for is my average sustained power output when I am climbing or riding hard on the flats. I have a pretty reasonable idea what a good number should be for me. Anything over 300 watts is good; Anything over 350 watts indicates that I am riding well.


Another benefit is to keep me honest during my rides. If I really want to ride a climb hard, if the ascent starts to flatten out near the top, I need to either shift up or pick up the cadence to keep the same power output. I was surprised at how just a 1-2% change in the grade of a hill can affect the power readings

so dramatically.


One thing I really like is the data that indicates how many total calories you have burned during your ride. Actually, the Power Tap displays the amount of energy produced in Joules, but by multiplying that number by 1.1 (thanks, Allen Lim)you can determine how many Big Macs you can eat post-ride.


For those of you into numbers, you can store the data from all your rides for future reference. After my first ride, when I hooked up the power meter to my PC, the first thing that flashed on the screen was "Seek a Pro Contract Immediately". And you think I am kidding.


I am still playing around with the Power Tap and learning more new and interesting things. Stay tuned for the details.



1,739 Views 4 Comments Permalink Tags: allen_lim, bruce_hildenbrand, lance_armstrong, power_tap, power_meter

Number 4

Posted by Bruce Hildenbrand Jun 15, 2008

I spent this past weekend in flood-ravaged Wisconsin where a week of torrential rains had left much of the southern part of the state underwater. It was time for the annual Horribly Hill Hundred(HHH) and luckily for Midwest cycling fanatics, the roads for the event had somehow escaped Nature's wrath. The HHH is a super-popular organized bike ride which takes in a lot of steep hills just west of Madison. When race registration opens on in February, the event fills its field of 1700 riders in about two hours.


OK, so I went to graduate school at University of Wisconsin-Madison and earned masters degrees in Food Science and Computer Science and served as president of the local racing club, The Two-Tyred Wheelmen, for several years, but imagine my surprise when I opened my ride packet and found my event number was 4 (four). How did I rate such a low start number? Thanks go to the folks at Saris Cycling. You know them as the people who bring you such great products as CycleOps trainers, Power Tap hubs and a whole host of bicycle racks for cars.


As part of the working cycling media, the Saris Cycling Group invited a number of journalists for a weekend of new product launches, bike riding and brat eating(this is Wisconsin after all). For 2009, Saris will have a really cool new line of trainers featuring both fluid and magnetic resistance and even a high end unit which measures power. Also new for 2009 the Power Tap line will be completely wireless with the top end hub featuring ceramic bearings. Power Tap hubs will be compatible with the Garmin 705 GPS unit as both use the ANT wireless transmission protocol now making its way into the public domain.


Checking out the latest products is cool, riding bikes is pretty fun as well which brings us back to the Horribly Hilly Hundred. I usually don't wear an event number when I do organized rides, but when you have number 4 out of a field of 1700, you gotta milk the opportunity so out came the safety pins. Several people wondered if I was a celebrity, which in my mind there is no doubt; others wondered if I had done something special on my bike something which seems to occur to me almost on a daily basis.


All kidding aside, it was great to be back in the Madison area enjoying the roads which originally kindled my interest in cycling and sharing that experience with both old and new friends not to mention those post-race brats. With hills as steep as 19% and many in the 14-17% range, the HHH is aptly named, but hey, I somehow survived. I had to. I had number 4 on my back and single digits carry added responsibilities.



1,159 Views 4 Comments Permalink Tags: bruce_hildenbrand, saris_cycling_group, horrible_hilly_hundred, power_tap, cycle_ops