Just Ride

So, I just finished reading Grant Peterson's Just Ride. Its an easy read, filled with a lot of wisdom about how to maintain a practical attitude towards riding your bike. I would say "…towards cycling..." but somehow I think Grant might agree "cycling" sounds too much like a racer's term ;). I really liked the book and do recommend it.

However, be forewarned that if you're the kind of rider that frets over grams of additional weight, wouldn't be caught dead riding platform pedals and toe straps or frequently monitors how your performance measures up on Strava or Garmin segments, you will likely not enjoy Just Ride as much as I did.

Grant Peterson is the founder of Rivendell Bicycle Works in Walnut Creek, California. Grant designed the frame I now ride, the Soma San Marcos, in collaboration with Soma Fabrications. I found that reading Just Ride was a little like reading the brochure on the San Marcos. I pretty much bought the San Marcos from that brochure alone without even so much as a test ride. Everything I read there suggested whoever designed that bike, which at the time I didn't realize was Grant Peterson, had a kind of mind share with me. They thought about bikes and cycling the way I did.

So, it was quite a welcome surprise to discover this gem of a book Grant wrote back in 2012. One overriding sense I had from reading it is that I no longer feel so much alone in the way "mainstream" cycling often appears completely absurd to me. Yet I fully participate in that absurdity.

Take my last ride for example. From the time I decided I wanted to ride to the time I was actually on my bike pedaling was about a 20-30 min ordeal. First, I have to take off all my (street) clothes and put on my HR strap; then, my cycling shorts, cycling jersey and cycling sox. Its all tight fitting lycra because we've all been told "cotton is rotten." Then, I have to fill my jersey pockets; left with id, health insurance card, credit card, cash, keys to house and cell phone, middle with clear lens glasses (because I will be out past dusk) and spare batteries for lights, right with gel packs, stinger wafers and ecaps Then, sun screen on my head, ears and face and arms. Then, I have to unplug my rechargeable lights and bike computer and put them on my bike. Then, I have to fill 2-4 water bottles and pump up the tires to 100 psi.

About this time through the process, if I happen to be wearing overall shorts, I invariably wind up realizing just then that I need to use the restroom; most likely a #2. Because my jersey doesn't unzip all the way down, I have to work it over my head without spilling the contents of my pockets and having it all fall into the toilet.

Finally, I am ready to put on my shoes. They are the most expensive shoes I own but I can't really walk in them. I can't use them for anything else but riding. And, shortly after I bought them, I had to drill holes in the bottom to move the cleat far enough back that my toes would stop going numb. Lastly, I put on my helmet and gloves and finally, after about 30 minutes of prep, I am ready to ride.

And, when I get back from my ride, I have to rush to the frig and down a protein shake because the first 30 minutes after completing a workout is when your body maximizes its protein uptake and that is important to re-build muscle (from all the damage you did during the ride).

It is these absurdities and many others that Grant Peterson raises our awareness of and offers more sensible alternatives to in Just Ride. Don't get me wrong. I like to challenge myself with difficult rides. I like to train myself up for them and I like to improve my "mastery" of cycling. But, Just Ride helps to remind all of us that we can wind up too often taking things a bit too far.

Except for two chapters of Just Ride, one on helmets and the other on target fixation, I either agreed wholeheartedly with Grant's perspectives or at least have found myself asking some of the same questions. So, using Grant's terminology, I guess as I have aged I have become a bit of an Unracer at heart.

But, it hasn't always been that way. Worse, I don't honestly know if I am an Unracer today because of a conscious choice (a dawning of wisdom with age maybe) to be that way or because I am really a wanna-be Racer who just doesn't have the legs ;)

I was surprised one topic Grant did not cover in Just Ride; sun protection. Having had 2 basal carcinomas removed before I was 50, I take sun protection very seriously now. Regardless of how hot it is, I typically wear long sleeve shirts designed specifically for sun protection as well as a sort of bonette underneath my helmet that completely covers my head and neck.

Helmets

Grant makes some good points regarding bike helmets. They really do not provide as much protection as we wish or might like to believe. Also, testing protocols don't faithfully represent real-world usage.

But, I disagree with Grant that the simple act of just dawning a helmet causes a rider to think s/he is that much safer for it and, in turn, will take more risks because the helmet is the for added safety. Honestly, I think most riders like to avoid any situation where they would actually need a helmet.

And, I cannot agree with Grant at all that its conceivable to be safer to ride without a helmet and simply pay more attention or adjust your riding behavior in other ways that reduce risk to compensate. About the only way I think that could be true is if you simply do not get on the bike to begin with. In that case, then yes, I'd agree you probably don't need the helmet either.

Rear Blinkers

Another point Grant makes in Just Ride is a blinking taillight can cause approaching (impaired) motorists to fixate on the dazzling light. Its called Target Fixation. Instead of warning them off, a blinking light draws them right to you and they crash into you. So goes the target fixation theory. In Just Ride, Grant writes that the phenomenon of target fixation is a good reason to use a steady light instead of a blinking one.

Now, if you believe the target fixation arguments and the only reason you use a blinking light is to save battery power, then why take the risk for the sake of some additional batteries? This is Grant's point and I agree -- that is if you believe the target fixation argument.

I myself am still not convinced that target fixation (the kind where a blinking light draws a motorist to crash into you) is a real or significant risk. There is really no evidence other than anecdotal.

I believe more visibility for a cyclist is always better. And, I believe a blinking light is more visible to motorists than a steady one. I also believe there is no such thing as a bike taillight that is too bright. I use a taillight in daylight riding as well.

So, I think you have to weigh the risks of reduced visibility (e.g. going with a steady light instead of a blinking one) against the risks of a motorist becoming fixated on your light. I think reduced visibility is the bigger risk. Nonetheless, I'd really like to see some more research on this issue. Maybe that's a good topic for a future blog post.

Biking is supposed to be Fun

I enjoyed reading Just Ride and found myself laughing with Grant through many of his comical observations of the influence of racing on the rest of us. At times, some of his commentary comes across a bit on the preachy side. Nonetheless, more often than not, I found myself nodding and wishing most of my riding friends shared the same opinions. In fact, I plan on giving this book to a few of my Racer oriented friends.

A final comment to leave you with is that if you've ever found yourself feeling burned out from cycling, Just Ride might have the cure. Its a friendly reminder that biking is supposed to be fun. With often comical descriptions, Just Ride helps us come to our senses about all things cycling.

Grinding vs. Spinning

In a previous post, I offered a hugely simplified potential energy analysis to determine a lower bound on the amount of power draw on my body on a recent climb.

The model consisted of two parts. The first was the potential energy of moving the mass of bike+rider up a hill. The second was the potential energy involved in moving the mass of the legs around and around on the cranks. Using these, I computed 198 Watts for the mass up a hill part and 46.44 Watts for the legs moving around on the cranks (at a 55 rpm cadence) part.

Here, I am curious about what this model might say about relative power draw for the same climb and same rate of climb except with variations in cadence. What if I climbed at the same rate but geared for a cadence of 60 rpms, 70, 80 or 90? What is the difference in power draw and how large a fraction of the total does the moving legs part become?

Using the same appraoch explained in a previous post, I've computed and tabluated the results below.

Tabulation of power due to two separate contributions; moving mass up a hill
and mass of legs in motion around cranks and as a percentage of the total.
This is based on same climb and speed of climb but just differnt gearings.

Climbers are often classified into two types; grinders and spinners. Grinders, like Jan Ulrich, opt for lower cadences on climbs, often below 60 rpms. Spinners, like Lance Armstrong, go for higher cadences, often above 85. All other things being equal though, there is a price to pay for that. A spinner at 90 rpms will draw more power just to keep the mass of his/her legs in motion at a higher cadence. In my example, the power difference is a tad over 30 additional watts. Another way to think about this is that each additional rpm requires approximately one additional watt of power from my body.

What this means for you, the rider, is that your cardio system is going to be working that much harder to accomodate the extra power draw due to your faster moving legs. But, your leg muscles and feet will have a bit of an easier go of it because although they contract more often they don't have to contract as forcefully and the pedal pressure is lower. So, this is a way in which you have some ability to tradeoff cardio capacity for muscular strength during a ride. By shifting to lower gears and spinning more, we place more load on our cardio system but lessen the load on our leg muscles and feet and vice versa.

For me and for most people I think, higher total power draw means higher heart rates too. I like to do whatever I can to keep my heart rate as low as practical. So, I tend to favor grinding. But, eventually, my leg muscles simply tire of the forceful contractions and I have no choice but to reduce gears and spin more or, more likely, reduce speed.

That suggests to me why spinning has more or less become the adopted standard among most elite racers. Late in a ride, after a lot of grinding, the leg muscles become deeply fatigued, unable to either contract with the same force or contract more frequently. Your only option is to reduce speed. However, spinning doesn't result in the same depth of fatigue in the leg muscles. Because it's placing more load on the cardio system your legs muscles can continue contracting at the same rate for longer.

If you can train yourself to master both grinding and spinning styles of riding, you give yourself an option to distribute the load on your body a bit depending on how you are feeling during a ride.

Pencil and Paper Power Estimates

I've never owned a power meter. But, I've always been curious how much power I produce on any given ride.

A great resource that motivated some of the analysis here is Bicycling Science. That book is just full of really interesting analyses, simplified models and equations related to cycling. If you're a cyclist that just happens also to be an engineering or math nut, you'll love it.

With some simple measurements, it is possible to use a basic potential energy analysis to compute a lower bound on the amount of power draw on the body for a given climb.

Its easiest to do this with a moderately long climb of nearly constant gradient. For riders in Livermore area, a good climb for this purpose is Del Valle. It is about a 1.6 mile climb of roughly constant 7.3% gradient. Some Garmin data for one of my rides up it is pictured below.

Elevation profile and ride data for Del Valle climb

Rider + Bike, Force through a Distance

The combined weight of my body plus my bike is about 200 lbs or 90.72 kg.

In the picture above, you can see it took me 14:03 to climb from an elevation of 768 feet (234.1 meters) to an elevation of 1385 feet (422.1 meters). That's a change in elevation of 188 meters in 843 seconds.

Now, potential energy is force through a distance. So, I need to know how much force my body + bike exerts in Earth's gravitational field. To get that I multiply the mass, 90.72 kg, times Earth's gravitational constant of 9.8 m/s/s yielding = 889 Newtons.

So, for the this climb, the total potential energy realized is 188 m * 889 N = 167132 Joules. Since this potential energy was realized over a period of time of 843 seconds, the power output was 167132 J / 843 s = 198 Watts.

Now, that is a lower bound on my power output. My actual power output was very likely a bit higher due to a number of losses including overcoming wind, flexing of components in the bike as well as other biological activities of my body such as breathing, heart pumping, sweating, shifting around on the bike, etc. Most important though, it does not include the power involved in simply moving the mass of my legs around on the cranks.

Power due to Moving Legs

To compute an estimate of the amount of power required simply to move the mass of my legs around the cranks, we need to know how much my legs weigh, how long they are, how long my cranks are and how fast I was turning the cranks.

My Garmin data also gives me cadence information and so I know during this climb I averaged about 55 rpms on the cranks.

But, short of cutting my legs off and weighing them, how do I compute how much my legs weigh? In particular, I need to know how much my upper and lower legs weigh and how long each is individually. Turns out De Leva (1996) has tabulated a statistical average for both weight and length of all limbs for a large population of men and women as percentages of there overall weight and height (I wonder if this data is somewhat skewed by the trend towards obesity in the average population).

Next, we need a very simplified model for the mechanical system representing my upper leg, lower leg, foot, and crank arms. To really simplify things, I have decided to actually decompose the leg motion into two parts we can superimpose (e.g. add) to compute a total power. This simplified model is surely not an accurate depiction of a real pedaling motion. But, its close enough for purposes of this power estimate.

Simplified mechanical model for moving legs while pedaling. The motion is decomposed into
two parts; one for the upper leg, rotating about the hip and one for the lower leg going straight
up and down above the pedal.

Power due to lower leg motion

In this simplified model, the lower leg moves straight up and down a distance equal to twice the crank length. On my bike, the cranks are 175mm. So, the total distance the lower leg in this model moves is 350mm. Next, in this potential energy analysis, we are concerned only with the part of the motion that works against gravity. Now, based on my weight of 180 lbs (81.65 kg), using De Leva's tables, my lower leg (shank + foot) weighs about 5.7% of my total weight or 4.65 kg. Again, we really need the force of the weight of my leg, so we need to multiply it by the gravitational constant, 9.8 m/s/s. So, the force of weight of my leg is 4.65 kg * 9.8 m/s/s = 45.57 Newtons.

So, the potential energy gain on the up-stroke of the crank is 0.35 m * 45.57 = 15.95 Joules. Next, at a cadence of 55 rpms, this potential energy gain happens 55 times in 60 seconds yielding a power output of 15.95 * 55 / 60 = 14.62 Watts. But, that is for just one of the two legs turning the cranks. So, the total power from keeping the lower legs in motion is 14.62 * 2 = 29.24 Watts.

Power due to upper leg motion

For the upper leg, one end is moving while the other end rotates around the fixed hip joint. The upper leg moves from almost vertical to almost horizontal, say between 70 degrees and 20 degrees relative to the horizontal. 

Near the bottom of the stroke, the amount of force required to rotate the free end of the upper leg is near zero because the motion is almost perpendicular to the direction of gravity. Near the top of the stroke, the opposite is true. Some simple statics equilibrium analysis should yield the forces involved.

For any given angle, in a statics equilibrium analysis, the sum of the forces is equal to zero and the sum of the moments is equal to zero. The only downward force is due to gravity which we can apply in our model at the center of the leg length. The motive force to move the leg is simply to overcome gravity. For any given angle, theta, the force F I think is 1/2*{leg force}*cos(theta). It is near zero at the bottom of the pedal stroke because the upper leg is just about hanging from the hip joint. It is near 1/2 the leg’s weight near the top of the pedal stroke.

To compute the total work in moving the leg, I believe the right answer is to integrate 1/2*{leg force}*cos(x)dx for x=0…pi/2. The result is 1/2*{leg force}*1/2(pi-2)*{length of leg}.

Using de Leva’s data, the upper leg is 14.16% of total body weight. So, for me at 180 lbs, the upper leg weighs 25.49 lbs (11.56 kg). Again, to get the force of the weight of my leg, we multiple by the gravitational constant yielding 11.56 * 9.8 m/s/s = 113.3 Newtons. Next, my upper leg length is about 2.4 feet or 0.732 meters

So, for one leg, we get a total work of 1/2 * 113.3 * 1/2 *(pi-2) * 0.732 meters = 9.34 joules. Again, for my cadence on this climb, this leg motion happens 55 times in 60 seconds. So, the total power is 2 * 9.34 * 55 / 60 = 17.2 Watts

Total power estimate for the climb

In this very simplified model for leg motion, we simply add the power contributions from both the upper and lower leg motions and arrive at 29.24 + 17.2 = 46.44 Watts.

So, the total power estimate for this climb is 198 + 46.44 = 244.44 Watts.

Although I don't ride with a power meter, I have done a little bit of time on a friend's CompuTrainer configured to impose resistence equivalent to powers in the range of 200-350 watts. On the trainer, 250 Watts felt like the kind of resistance I am accustomed to on a moderate length and gradient climb such as the one analyized here. So, that some emperical evidence to suggest the analysis here may yield a decent estimate of power.

It would be nice to be able to include power due to overcoming wind. In this case, since I was on a climb, my speed really wasn't very high. Going through still air at that speed there just isn't that much resistence due to wind. But, in a later post, I'd like to investigate a similar power estimate for my size (frontal area) to overcome wind drag while on a flat course at a higher speed.

A final disclaimer

This analysis is not aimed at computing a measurment similar to what you would get with a PowerTap power meter. A PowerTap power meter measures the power actually produced by your work at the rear hub. This analysis is aimed more or less at the power draw on your body. So, I think this means that this analysis is likely to yield a higher number than you might see from your PowerTap. On the other hand, this analysis, because it is using a basic potential energy model, is neglecting to include a number of factors (flexing, compression/expansion and even heating of bike and body components, etc) that add to the power output. That means, that this analysis represents a lower bound on the power draw on your body.

Safe Riding in Traffic

The following is a post written by Mike Monk, also known as the Bama Cyclist, back in 2011. Mike was our tour leader for my 2013 cross-country tour. He has lead many tours for America By Bicycle all over the country and has crossed the country on bike, many, many, many times. I learned a lot from him and asked his permission to post some of his advice regarding safe cycling.

Sometimes, I think in our rush to get a PR or stay ahead of the guy behind us, we often forget these simple safety rules when riding in traffic.

Mike Monk On Riding in Traffic

Some hazards we face as cyclists are just part of the environment and beyond our control...pot holes, bad angle RR tracks, broken pavement, slick manhole covers, loose gravel, blind corners, loose dogs or other wildlife and sun glare in the late afternoon just to name a few.  Beyond these "natural" hazards we deal with everyday, there are also countless situations with the potential to be hazardous to our safety that we can control. Unfortunately, many cyclists have riding habits that relinquish that control and defer the responsibility to someone else. 

A common example is how we control our safety environment when we encounter stopped traffic at traffic controlled intersections.  When you approach a line of cars waiting at a stop light, do you ride up the right side of all the cars and continue through the intersection in disregard for the light or sign?  Do you weave in between the cars working your way up to the intersection and then go your merry way?  Do you ride up the right side and stop at the light until the control changes?  Or do you get in line with the traffic and wait until the traffic starts to move?

I hope we can all agree the first two of these scenarios as unacceptable in any situation, the third is maybe OK in SOME situations, and the last WORKS IN ALL situations.  By getting in line with the traffic, you give motorists notice that you are a law abiding vehicle that has a place in traffic, you position yourself in a place where you can be seen, and you won't get pinched against the curb or run over by being in the motorist's blind spot.  Now let's discuss the situational one.

Any time you approach a vehicle on the right side, you may be the only one that is aware you are there.  You have just created a situation where you have relinquished control of your safety to someone else. Critical members involved in your safety are not aware of the environment...and YOU are the one who is most vulnerable (even more critical considering all the other distractions the driver is dealing with...like talking on their cell phone and items on the edge of the roadway like the photo above left).

I know of at least 5 people who have been killed by doing this seemingly harmless maneuver.  They pulled up beside a vehicle on the "blind" side and the vehicle turned right and ran over them or just pulled forward with a slight swerve to the right catching the cyclist in a mirror, bumper, or wide trailer.  All of these tragic accidents could have been avoided had the cyclists not placed themselves in the motorist's blind spot...they gave up control of their environment/safety.

The situation I'm most referring to is when there is no dedicated cycling or shoulder to the right of the traffic.  If there is a bike lane or shoulder and you decide to approach the intersection on the right of a line of traffic as in the third situation mentioned above, you should still approach on the right with extreme caution and never stop in a vehicle's blind spot.  Even then, it's not the smartest thing to pull up beside the front car who may still be thinking about a last minute right turn and not see you.

With no dedicated lane for cyclists, the safest place, and in my view the most responsible place to be when the traffic stops, is to be in line with the traffic about 1/2 or 1/3 into the lane from the right...in front of someone's windshield and right behind the vehicle in front of you.  If you can't see the eyes of the motorist in front of you in his rearview mirror, you are not where he or she can see you.  As soon as the traffic starts to move faster than you can maintain, then pull to the right the appropriate distance from the road edge and be part of the traffic flow.

One other consideration if you have to squeeze in between the shoulder and the cars to move to the front, cars that have already had to pass you on a narrow lane will have to work their way around you again.  You may find they won't give you as much room the second or third time they have to pass you.

Assuming that adhering to traffic laws is a given, one of the most important safety habits you can have is to be visible.  That's more than just wearing bright colored clothing...you have to be positioned where you are visible in your environment.  That means not ever riding or placing yourself in a blind spot of a motorist.

Measuring bike "fit" using a digital camera

When I was a sophomore at UC Davis in 1983, I purchased a brand new Centurion Pro Tour 15. It is a beautiful bike and I still have it and love it. I think it was $550.00 at that time. Last year, when I turned 50 and my bike turned 30,  I rode it on a cross-country tour. I blogged about that ride here.

The reason I love that bike so much is that it is a really, really comfortable ride. The bike fits me quite well and I can pedal for hours without getting sore other than the standard fatigue and muscle soreness from all the work I am doing.

In any event, I wanted to measure the "fit" of the bike to help me compare it with other bike frames I am considering buying. I wanted to know how far off the ground the bottom bracket is, how far up above and set back the saddle is, what the angle of the seat tube is, how far up and forward the handle bars are, what the wheel base is, etc, etc.

I decided to try to use a digital camera to measure the bike "fit". I believe the approach works remarkably well.

Photoshop image of bike with various guidelines drawn in red.

Taking a picture of your bike

Its really important to take a "proper" picture of your bike.

The photo above shows the original color image of the picture of my Centurion Pro Tour. I made a few mistakes when I took it. The first is obvious. The background wasn't the best. It would be much better if I had hung a white sheet or some solid, light color sheet against which all the components of the bike would stand out. So, thats my first piece of advice. Choose a constant color background.

Also, be aware of shadows and direction of lighting. It is probably best to illuminate the bike with a bright light source near the camera. Diffuse light is of course better. A lot of light from an oblique angle from one side of the bike can cause non-uniform illumination on key components facing the camera and will result in making it harder to judge the 'center' of things like wheel hubs, cranks, etc.

Next, make sure the bike is standing perfectly vertical. You want the center plane of the bike frame to be as close to exactly parallel to the camera's image plane as possible.

Next, you want to "flatten" the bike in the image as much as possible. You do this by making sure the distance between the camera and the bike is large compared to the "thickness" of the bike. But, the further you move the camera away from the bike, the smaller the bike will be in the image. It will occupy a smaller number of pixels and any measurements based on counting pixels will have greater error. So, its best to have a digital camera with a high optical zoom, say 20x or more and a large number of pixels, say 10 Megapixels or more.

Next, you need to include something in the picture that you know the exact length of (a scale cue) so that you can later calibrate Photoshop's measuring tools. If you look closely at the top tube in the above picture, you see a white strip of paper hanging from it. That paper is cut to to exactly 12 inches in length from top to bottom. Once I have the image in Photoshop, I can use tools there to count the number of pixels in those 12 inches and from that, calibrate the physical size of a pixel. Again, its really important that that scale cue is as nearly parallel to the camera's image plane as possible.

Finally, you want the bike's front and rear axels (center of the wheels) to create an as close to perfectly horizontal line as possible. You don't want the image of the bike rotated relative to the horizontal line. On the other hand, once in Photoshop, you can measure how far off the horizontal it is by drawing a horizontal guide and then having Photoshop rotate the image slightly to correct it. 

I mounted my camera on a tripod that also has a small level on it. I made sure the tripod was level, stood about 20 feet (more would have been better) from the bike and tried to position the camera so that the center line of the camera's lens pierced the bike frame's plane at about the geometric middle of the frame. I then adjusted the zoom so that the bike filled the image. I took several pictures, keeping the one that was most in focus.

Measuring things in Photoshop

First, a disclaimer. After doing all this work with a very high quality image in photoshop, I have somehow now lost that image and have only some lower resolution PDF files (with red-lines over-written for different geometric components). So, the images in the examples here are kind of fuzzy. Your own images I am sure will be much cleaner and clearer to work with. This just gives you an example of how to take measurements.

After bringing the image into Photoshop, the first thing you will want to do is probably crop the image to eliminate wasted space in the image an center your bike in the image. After that, you will want to set a custom measurement scale. In the panel options for the Info window, set Mouse Coordinates to Pixels. Then, using the ruler tool, measure your scale cue.

Using Photoshop ruler tool to measure scale cue

The upper left corner of the Info window displays an angle, (A), and a length, (L). The length represents the length of the line between Start and End points measured in units of pixels. In this example, it comes out to 606.6 pixels.

Next, you set a custom measurement scale by going to Analysis->Set Measurement Scale->Custom

Photoshop accepts only integral values for the pixel length entry. But, notice that the window now displays the scale as "607 pixels = 12.0000 inches." Save your image.

With the measurement scale set, you can now use the rule tool to measure both lengths and angles on your bike. But, when using the ruler tool, be sure to check "on" the "use measurement scale" option for the ruler.

On other thing you may want to do is ensure that a line drawn between front and rear wheel hubs of the bike is perfectly horizontal. In other words, make sure the image of the bike is not rotated relative to the horizontal. To do this, choose the ruler tool and then draw a ruler between the center of the front and rear wheel hubs. The Info window will show what the angle of that line is. It might show something like 0.5 degrees.

Newer versions of Photoshop have an option to 'straigthen' a ruler. If you have this option, use it. Its the simplest way to rotate the image so that the ruler you drew is perfectly horizontal. On the other hand, if you don't have this option, you will have to rotate the image. So, find the controls to rotate the image (by an arbitrary angle) and enter twice the negative of the angle you measured. Why twice? Well, that's because Photoshop will rotate the image about its center. And, the angle you measured is relative to the center of your front wheel hub. Assuming your bike is centered in the image, your front wheel hub is off to the left (or right) and so you need to rotate the image about its center through a larger angle.

You can use Photoshop's "guides" to set horizontal and verticle guidelines that intersect at key points such as the center of each wheel hub and the center of the bottom bracket/cranks. Doing this allows you to ensure that each time you draw a ruler originating or terminating at one of these points, you can make it "snap" to the same point making your measurements more consistent.

As an example, here is a measurement of head tube length and angle.

Note that I have set the Panel Options for the Info window to show the current scale. However, also note that the Length, (L) measurement in the upper right of the Info window is not using the measurement scale. It is using the image's default scale. The correct length measurement is shown in the toolbar menu near the top of the image (L1) of 7.4 inches. The head tube angle is measured 71.5 degrees.

The angle measurements in Photoshop are always from the positive X-axis (e.g. from a horizontal line moving to the right).

After doing this exercise, I later found an on-line reference for the 1984 Centurion Pro Tour 15 and can confirm the measurements turned out to be less than a quarter percent different from the published specs.

Comparing with another frame

The Centurion is a beautifully chromed lugged steel frame. I really like a lugged steel frame. In 2013, I spent some time looking for a comparable frame but designed for modern components such as 700c wheels and 130mm rear hub spacing.

I took a close look at the 2012 Bianchi Dolomiti. To compare it to my Centurion, I used on-line frame geometry specifications for the 59cm Dolomiti. Using the bottom bracket as a sort of "origin" upon which to overlay the two frames, I worked backwards in Photoshop drawing lines for lengths and angles of various Dolomiti tubes. The result is pictured below. The Centurion is in red and the Dolomiti is in black.

Comparing Centurion (red) with Bianchi Dolomiti (black).

The head tube angle on the Dolomiti is a bit steeper, the wheel base is quite a bit shorter due to shorter chainstays. The seat tube angle on the Dolomiti is a bit more relaxed too and a bit higher. On the other hand, the seatstays on the Dolomiti are a bit steeper. But, the top tube length and seat tube height are a pretty close match. I think I would have been happy with the 59cm Dolomiti.

In the end, I decided to go for the 59cm Soma San Marcos (geom). I just did my first double century, the Eastern Sierra Double, on that bike and think it is turning out to have been a great choice.

Getting a true "3D" model of your frame

A friend of mine works at Google and I happened to ask him about how to maybe use multiple views of my bike frame to build up a 3D model of it. He suggested something called Voxel Culling. The way it works is that you sort of hang the frame by a string in front of a camera and then let the frame twist around a full revolution while the camera snaps a slew of images of it (maybe even a video). Then, feed all these images into some special 3D reconstruction software designed for this purpose. More on this in another post.

2014 Eastern Sierra Double

I did the Eastern Sierra Double Century this past weekend with my good friend, Steve Capie. I did it on a new frame I am still getting used to; the Soma San Marcos.  My ride data is here.

The Eastern Sierra Double is by far the most picturesque, most unusual terrain and climate zones of any ride I have done. I found it even more interesting terrain and unusual place to ride than the Death Valley Double.

It starts and ends in Bishop, CA, at an elevation of about 4,500 but goes over Deadman and Sage Hen passes, both of which are over 8,000 feet, around June Lake and up to Mono Lake. Here is someone's ride with gps route from 2013 and my buddy, Steve's elevation profile is below.

Elevation profile for 2014 Eastern Sierra Double Century (Courtesy of Steve Capie)

The weather we had was close to perfect. It was mid-50s at the start in Bishop but temps rose 10 degrees there in just 2 hours. In fact, by early afternoon Bishop was seeing high 80's. Fortunately, by that time of day, we were already far north of Bishop at higher elevations and lower 70's temperatures.

On the other hand, it was very, very dry and there were winds of 5-15 from all directions most of the day. I needed 3, 20 oz water bottles between stops. Yet even though the air temperature was low 70's, the intense sun at these elevations without the wind was unpleasantly hot!

The climbs are gradual. Rarely do you see any gradients over say 7%. On the other hand, because the climbs are gradual, you spend a lot more time climbing than you'd expect for a 10,000 foot day. The high elevations effected me some in that my breathing was a bit more labored but I otherwise felt fine.

The descents on this ride are fantastic. I hit 50+ mph on several occasions.  There are few places where turns require braking. The road surface is great to excellent for 90% of the ride. On descents rarely are there trees or other things to shade the road surface and obscure your view of hazards. In addition, most of the route is over roads not frequently traveled by cars. On the other hand, you do wind up riding maybe 30+ miles on highway 395. But, the shoulder on these miles is great.

I think the most stunning part of the ride was June Lake Loop. The climate zones and terrain change so dramatically in those 20 miles and it is all very, very pretty. June lake looks like something out of an idealic mountain getaway and Grant lake looks like the Dead Sea.

The only downside I see to this ride was the food choices at rest stops. Many riders who have done the ride before know this aspect of the ride and carry extra food in backpacks. There are only 6 stops over the whole route but they are strategically placed for level of effort required to traverse the interveneing terrain.

Because most of the climbing is in the first 100 miles, it took us 8.5 hours to finish the first half and 5.5 hours to finish the second half. It was only the second time I have finished a double in daylight.

I highly recommend this ride to anyone wanting a beautiful but slightly challenging double century. I really wish I had stopped to take a lot of pictures. But, sadly, I was often not in the mood to slow down my pace or stop.

The official finishers list is here.