Zagrepcanka 512 – tower running

Last month somebody came up with the idea of organizing a tower run in Croatia. This has Zagrepcanka_dannever been done here before, but is very common in some other countries (like the popular Empire State Building run-up). I found out that there is even a tower running federation, with plenty of races around the world – here is the link:

I had a feeling that the race would be a hit in Croatia. Although the organizers limited the number of participants to 250, in a few days there were 405 applications for the race. I joined in. The race was unusual in Croatia for many things: live results, chronometric start etc., which made it quite interesting. No one had an idea of what to expect, and neither did I.

The race was set in an office building in Zagreb (a bit over 100m with an antenna). There were 512 steps to pass to get to the 26th floor. The whole thing was massively covered by the media. Predictions before the race: 5-6 minutes for the winner’s time… Results:

Gabrijela Šalković won the women’s category with 3:52, and Igor Ermakora the men’s category with a result of 2:54. He was the only person to beat the 3 minute mark. I was quite happy with my 29th place (timing 3:40). Well – till next year! Let’s plan to bring the record down 🙂 220165_10151299214564004_1132343768_o

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Which manufacturer made my retina screen?

In the process of getting a new computer, I had the choice of getting the new retina macbook pro. After searching the web, I found out that there are some ghosting and image burn problems with some of the displays on rMBPs out there. In the end, it turns out that there are 2 manufacturers who actually make the screens: LG and Samsung. The LG screens show problems, whereas the Samsung ones don’t (at least not yet).

Well, how do you find out which manufacturer made your screen? This seems to be a question that is bothering a lot of people out there. Simply going to system properties won’t do you much good – you won’t find anything there. I found a workaround which will help you in this case. Solution – open your terminal and type:

ioreg -lw0 | grep IODisplayEDID | sed “/[^<]*</s///” | xxd -p -r | strings -6

Read the output. If the prefix to the output on your screen is “LP”, well then, I am sorry – you are looking at an LG screen.

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Bike assembly – frame painting

The first part of the bike to deal with is the frame. The frame determines the kind of bike (mountain, full suspension, race etc.) and the size of the frame determines the size of the rider. I had an old frame (2004 Gary Fisher Marlin) which was quite worn out, so I decided to use that, since it was free 🙂 and I was sure the size was right since it was my frame to begin with. So, here is DIY on frame restoration and painting:

Ingredients and tools:

  • an old frame, your size
  • sanding paper in different grits, 60-1200
  • paint removing chemicals (optional)
  • can spray paint, primer, color and finisher
  • stickers for the bike (optional)
  • some rags or toilet paper for cleaning

Time and cost:

This can take anything from one day to a couple of weeks (if you are very thorough and want to make it look professional). The cost was close to zero for me, since I had the materials around, but I imagine that you need to buy sandpaper and can spray, which will set you back about 10-15 pounds, depending on the number of cans you buy.


1. Completely remove all the items from the frame. This includes the bottom bracket, bolts, v-brake pins etc. Be careful when taking the bike apart. Some areas of the bike are quite complicated to take apart. If you’d like, you can take notes and pictures of how the parts were aligned when you took them out, so that you can get them back in correctly. Otherwise, I plan to describe the assembly step-by-step, so you can find instructions here as well. Removal without deforming some parts is difficult without the proper tools, so consider taking your frame to a bicycle shop for any step of the break down.
2. Degrease the bike using a de-greaser of choice (gasoline will be fine) and remove all Frame_cleanof the existing paint with medium-grade sandpaper (60-80 grit). If you have some paint removing chemical, you can use this as well. This step is very important, so make sure you get everything off your frame. This may take time, so be patient. If there are any dents or wear marks which you want to fill in, this is the time to do it. Use putty or something similar to produce a smooth surface and sand it down well afterwards.

3. Hang the bike in a well-ventilated area by the bottom bracket to ensure that paint doesn’t clog up there. PrimerYou can fill the bottom bracket tube with something as well. Apply a primer with very thin coats for the best finish. Follow the instructions on the can (typically spray about 20-30cm from the surface). Start at the joints and bottom bracket in the frame. These are the hardest bits to paint, and the easiest places to get runs or miss a spot. Wait about 15-20 minutes between coats, and don’t worry about it if you don’t fully cover the frame in the first or second coat, because you will be applying several coats. You can put 4-5 coats on the bike, since this is the most important layer of paint. Allow the frame to dry for 24 hours.

Notes: Make sure you buy the right type of primer, as the color of the primer depends on what your final color will be. Look for a primer that resists rust. If you are refurbishing an aluminum frame, you may need to get a special primer or an alomide coating. Wear goggles and a mouth mask. If there are small spots where the paint was thick (running paint), sand it down with finer-grit paper (500 grit).

4. SMaskingand the primer using 200-300 grit sandpaper. If you wish to paint the frame in multiple colours, you simply apply the lighter paint first, applying till an even coat is achieved (3 or 4 coats), then mask over the area you wish to remain the light colour, and paint the darker color on. Additionally, if you already know where your dark areas will be, you can mask over them now. Use a tape which you can easily remove later. I found that the painter’s tape works best.

5. Now, put on the main coat of paint. Once again, make sure your bike is clean of dust Half paintedand any grease. To apply the color, follow the same steps as you did for the primer, ensuring you apply thin coats until you have a uniform finish. After painting, let the paint dry (ideally another 24 hours) and remove the masking tape. Once this is done, check if you are satisfied or need to make any corrections. You can make small corrections with a thin brush. When you are happy, put the tape on the now colored area. You will apply the darker coat on the non-colored area. In this case, this will be black.

6. Now paint with the darker color the same way you did with the lighter. Apply several coats and leave for 24 hours. When the paint dries, sand it down again, this time with 1200 grit paper. This is “water grade paper”, so the areas that you are sanding need to be wet. You can use a water spray to help you do this. Dry the frame well. If you have any stickers you’d like on your bike, stick them now. Finally, apply the clear lacquer in several layers. It is important that you do not have the spray can too far from the surface as you could end up with a rough surface. Leave for 24 hours.

7. Thread paintFinally, after the painting is done, there are few more small steps that need to get done. One is to clean any threads on the frame that might have paint on them. You want the threads perfectly clean. You can use sanding paper to this, but an easier way would likely be to use paint remover. That will do the job extremely well, at least from my experience (compare the images).  When this step is done, you can apply some wax on your frame to make it nice and shiny. I have Thread cleansome wax I use for all the bikes – you can also use car wax or any other shining agent you may have. Put a chainstay protector on the frame if you’d like as well. Finally, I added the v-brake pins (commonly called bosses), since I intend to use v-brakes. Before inserting them, I cleaned them in some gasoline and applied some anti-seize compound.

That’s it, your frame is done – hopefully you are happy of painting it yourself!Frame_done

PS. I will make a PDF of this and other manuals when the entire bike is complete (like a DIY bike book).

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What is my ideal body weight?

A question I often get asked by some of my fellow sportsmen (I suppose because I am a scientist) is “What would my perfect weight be?”. This question is not really easy to answer, more so given that the society is plagued by the “Body Mass Index (BMI)” myth. Let me explain a bit…

The BMI is an index made up sometime in the seventies to approximate the healthy weight range for individuals. It is a formula which takes your weight (in kg) and divides is by your height (in m) twice. For example, if you weigh 100kg and are 200cm tall, then your BMI would be:

BMI = (100kg/2m)/2m = 25 kg/m^2

Now, according to health guidelines from those times, this person would already fall in the overweight range. I think that from the viewpoint of modern society, if you saw someone like this, you might even call him slim!

A much better “index” one should look at is the percentage of fat in the body. This can be measured by modern scales (which will be approximate at best), or even better, by a fat caliper (buy one for a few bucks on amazon). Here is a much better way to calculate your ideal weight:

Lean Body Mass/(1- Desired Body Fat Percentage)

where the lean body mass = Your Body Weight – (Your Body Weight x Your Current Body Fat Percentage). Just to be clear, your LBM is your “fat free” mass, in other words, everything in your body that’s not fat: your bones, blood, muscle, and organs.

Let me give you an example of this ideal body weight formula in action so you can see why it’s so useful. Let’s take Jake who is 90 kg and has 22% body fat. Using this information, we know that his LBM is 70.2 kg and the amount of body fat he has is 19.8 kg. So what should Jake’s ideal weight be? Well that’s really up to him. For most men, a mid double digit body fat percentage of say 15% is considered pretty good. This depends on the gender and age. Here’s a chart for your reference:


To get a better idea of how this actually looks, here are some (motivational) images as well:


OK, so now that you have determined your lean body mass and decided on what body fat you are aiming at, you can calculate your new “ideal” weight. Let’s continue with our example. Let Jake be 30 and have LBM of 70.2 kg. Further, let’s say he decided he wants to have 13% body fat. This means his ideal weight would be:

Lean Body Mass/(1- Desired Body Fat Percentage) = 70.2 / (1-0.13) = 80.7 kg

Well now, you might still ask – but what if he is really tall, say 220cm? Wouldn’t this weight make him underweight? Indeed, if we calculated his BMI at this point, it would be:

80.7/2.2/2.2 = 16.7

which is too low, and indeed, he would likely be underweight. Why, then, doesn’t this fat formula work? The reason is simple – fat is bad for your health and the doctors will only tell how much (in fact, little) fat you should have. No one will ever tell you how much muscle you should have, because it can’t hurt to have too much (well, in extreme cases, it can, but no normal person ever gets there). So, I thought about this a little and concluded this – it is likely best to be built like an athlete. An athlete build depends heavily on the sport one is active in. To make a good estimate, I took the averages of (about) 10000 athletes that were at the Olympics this year. I found data for both men and women, which you can see here:

Olympic_StatsOlympic_Stats(1)For men, the median weight and height are 78kg and 182cm. For women, 62kg and 170cm. The calculated BMI for men this way is 23.55 (almost overweight!) and for women 21.45. So if Jake wants to have this BMI, he should weigh:

Weight = BMI * height * height = 23.55 * 2.2 * 2.2 = 114kg

So, Jake, at this point, you are not overweight, but you are fat! Jake should reduce his fat to 13% of body mass and build some muscle (to reach the “ideal” weight).

A summary of all of this – to find your ideal body weight:

1. Write down your body mass and measure your body fat percentage
2. Calculate your LBM = body mass * (1-body fat percentage)
3. Look into the chart and find your ideal body fat percentage (or decide on one)
4. Calculate your “new” body mass BM=LBM / (1-desired fat percentage)
5. See if your “new” body mass is close to the ideal BMI for athletes
6. Try to increase/decrease your mass (muscle AND fat) to reach the ideal BMI

Any questions, just ask!

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Convert multiple audio/photo files in one step

My wife asked me to convert a number of FLAC files to MP3. Apparently, this was supposed to be very easy to accomplish in Linux. She found a web site with a script that, unfortunately, worked only in very specific cases. I managed to convert the script so it works on all UNIX systems (including OsX), by using the bash shell (terminal).

To actually do the conversion, you need to have flac and lame installed. Nothing else is required. There were several problems I ran into by using the original script. First of all, as many shell scripts, it is written in such a way to accept only file (and folder) names which have no spaces or brakes. This, for a modern user, is not acceptable. I managed to find a way around it using “globstar”. Here is the script:


# Ensure required parameters are passed in
if [ -z “$convert_dir” ] || [ -z “$output_dir” ];
  echo “Usage: flac2mp3 rip_dir output_dir [bitrate]”

# Default to 320 kbps if bitrate not specified
if [ -z $bitrate ];

# Get the list of files to convert and convert each file, one at a time
shopt -s globstar
for file in “$convert_dir”/*.flac
  outputname=`basename “$file”`
  flac -dc “$file” | lame -b $bitrate – $output_dir/”$output”.mp3

echo “Conversions complete!”

That’s all! To install:

Copy the text above in a file named “fl2mp3” and place it in your /usr/bin folder. Change the permissions on the file to 755 (sudo chmod 755 /usr/bin/fl2mp3). To use the script, simply type (anywhere on the computer you might be):

fl2mp3 input_dir output_dir [bitrate]

where you change “input_dir” with the folder where you have your flac files, and “output_dir” with the folder where you want your mp3 files. These folders may be the same, if you’d like it so. [bitrate] switch is not necessary – the default is 320 mbps, but you can put any number you like.

To extend a bit on this, I will add a nifty way to resize a lot of photo files in a directory. I ran into this problem when I had to upload a bunch of files on flickr, but they were too large. You could modify this script, but there is even an easier way. You have to have imagemagick installed (if you don’t, just type

sudo apt-get install imagemagick

in your terminal. Go (within the terminal) to the directory where you have your files and simply type:

mogrify -resize 50% -format jpg *

In this example, all the files will be resized to 50% of their original size (each dimension, hence, the file size will be 4x smaller than the original). The jpg switch determines the output file format. You may also specify width and height by the following command:

mogrify -resize 800×600 -format jpg *

but this may be unpractical, unless all your original files are in a 4:3 ratio.

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How to assemble or restore a bicycle – part by part

It’s been a while since I last wrote… I guess the laziness of the winter hours combined with plenty of work got the better of me.

In any case, to keep my hands busy during this winter, I decided to build a bicycle from parts. The decision came to me easily – I need a bike to ride around the town and I had some old bicycles/spare parts lying around. It will not be a serious mountain bike, but it will be built around a MTB frame (2002 Gary Fisher Marlin). I plan to assemble and restore the entire bike part by part. The first thing to do will be the frame – cleaning and re-painting – so stay tuned for a Do-It-Yourself on frame restoration (probably in a couple of weekends)!

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Zagreb marathon

As some of the readers know, I am Croatian, so I’ll promote some of our races with the intention to get some of you interested. One of these took place today – the Zagreb marathon. This year marks the 21st marathon, and it is still a growing event—but, with a much smaller field than most other city marathons in Europe.

Last year, 268 runners completed the marathon (including the city mayor), while 666 finished the half marathon. I went running on the half marathon last year. Public interest in the event was relatively low, and it was not uncommon that residents loudly complain about the city center being (more or less) closed to traffic.

The start/finish area are placed on Zagreb’s spacious main square (Ban Jelačić Square), and there is plenty of room for marathoners, half marathoners, as well as for citizens running the 5K citizens race. The route is an out-and-back mildly undulating course, starting eastwards to the suburb of Dubec, and then back to the city centre. The next leg looks westwards along Ilica (Zagreb’s main shopping street) and back again to Jelačić Square. Participants in the full marathon run two laps.

I finished the half last year with a time slightly under 2 hours (1:59:52), which was my goal at the time – I was a novice runner. This year I’ve decided to take on the 5K citizens race with my wife for a number of reasons (haven’t really trained for long distances yet, an upcoming trip etc.). Unfortunately, as is often the case, the start was very crowded (around a 1000 participants) and you had to fight your way through slowly moving bodies. I’d say this cost me about 1-2 minutes tops. The weather was nice, 18 degrees Celsius, lightly cloudy. I hadn’t set out to break my PR, but I had a decent run. Time at the finish – 23:30.

Here is some info for those of you who might be interested:

Country: Croatia
Venue: Zagreb (Ljubljana 139km, Graz 183km, Trieste 228km, Budapest 346km)
: early October (Sunday)
Distance: 42.2km; 21.1km; 5km
Start time: 10.00
Start and finish: Trg bana Jelačića (Ban Jelačić Square)
Route: course map
Entry fees (21km, 42km): 150 HRK (ca. 20 EUR)
Event website (in English and Croatian): Zagreb Marathon
Tourist information (in English and Croatian): Zagreb Tourist Board

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A biker’s delight

Last weekend I got a chance to try out how the new XC bike behaves on a real mountain track. In Croatia, there are plenty of mountain bike (XC) tracks, but only a few provide a real challenge and are so picturesque. One of these is said to be among the most beautiful in Europe – the Velebit MTB marathon track. The track traces a few paved roads, but is mostly set on gravel and some mountain paths. Starting from the town of Senj, you have to climb 1594 meters to reach the mountaintop at the Zavizan mountain house – this constitutes the first 38km of the race. After that, there are some downhill rides through the nature, which will take your breath away (both athletically and due to scenery). Formally, the race stops at kilometer 88, after one last climb, finally reaching the so-called Dabarska kosa.  There are another 20km worth of riding after that point, descending to the town of Karlobag, but is only downhill and serves to relax after a long ride.

This year some 130 riders registered for the race (but I am not sure how many actually showed up on the starting line). Unfortunately, there were no celebrity riders to add luster to the lineup. I got a ride with a local biking club, starting the day at 4am to get there on time. The start of the race was scheduled at 10am, and we were already there by 8am, so there was plenty of time to warm up and think hard about why someone would actually do something like this in the first place. Well, at around 10am we hit the ground running, as it is always the case at big races! This turned out to be a mistake, since we had about 40km of grueling uphill riding ahead of us. The scenery, I must say, is amazing. The weather held up and gave us perfect riding conditions. However, even with the best of circumstances, after about two hours without a chance to stop and relax due to the gravel roads, one starts being a bit desperate. Well, it pays off – about three hours after start, after finally reaching the mountaintop, you sit back, relax and eat that well-deserved candy bars you are packing in your backpack. Even though at this point I had the feeling that the difficult part of the race was behind me (and about 40 riders have already given up), I had a gut feeling that would be too easy.

Soon enough, I was riding through the forest, downhill on gravel paths, having barely any time to look around – I was just making sure I am not thrown off the bike under these riding conditions. Troubles started piling up. I made a wrong turn (figured that one out after not having seen anyone for a while), got lost once and even had to repair a punctured tire. These roads are not a walk in the park. After the race, I even heard there was a bear sighting on one of the roads! Anyway, these setbacks cost me about an hour. Time at the finish – a little under 7 hours. Not too shabby, considering I haven’t been riding for a while and the bake has never been tested. The top finishers almost broke the race record – 3h55min. There is still plenty of work to do before I can ride that fast (and be a bit crazy, now that I think of the dangers of the track)!

After the race, I must say I am impressed. I had to ascend almost 2.5 kilometers and had a plethora of troubles, but the scenery is just astonishing and I would recommend the race to everyone. Come and see these parts of the world! In fact, you don’t have to race – simply bike or hike! I, for one, know that I am coming again next year, only this time to chase down my PR and enjoy the trail, not just to finish. Photos by Goran Pozek.

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How to make a wall ball

Plenty of useful crossfit exercises can be done with a wall ball. Instead of buying an expensive factory produced ball, you can make one yourself for a bit more than 5 pounds.

Ingredients and tools:

  • A basketball, not too expensive
  • A knife, a funnel and about 10kg of salt in pellets, a pump (optional)
  • A rubber patch kit
  • A marker (optional if you make sets of balls)

Time and cost:

bsketball – 2.5 pounds, salt – 2 pounds, patch kit – 1 pound. Time: half an hour.


  1. Take a basketball (you can also use other kinds/sizes of balls according to your preference – I also made a wall ball with a handball sized ball) and make an X incision with a knife. Don’t make it too big, just enough to fit a funnel in it. Insert a funnel in the opening.
  2. Start adding salt pellets through the opening. I aimed for a 9kg ball and found that I should fit about that much salt pellets in a basketball. Salt pellets are a bit more expensive than sand but they are better for a variety of reasons – if you puncture the ball, they won’t leak out, they fill the ball more uniformly etc. I found out that using a pump while filling helps. Every now and then I would add some air with the pump (through the usual vent on the ball) and the pellets would sit nicely and fill the ball in a better way. It will take a while to fill the entire ball, so be patient.
  3. Once you are done with the filling, take the funnel out and patch the ball with a rubber patch kit (just follow the instructions on the box). If you plan to make more balls of different sizes and weights, I recommend using a marker to write down the weight of the ball somewhere on it.

You can get a PDF of this manual here: How to make a wall ball

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Lightest hardtail XC bike ever

Imagine you wanted to build the lightest XC bike ever. After browsing around the Internet a bit, I found this and wondered how low could one go in weight? Is it possible to go sub 5.5 kilo? As an additional issue, I would demand that the bike has disc brakes, a front suspension, be in large size, have a 2×10 system with a normal size non-aluminum cassette and have no tubeless. Also, I would want any parts that break easily (like some carbon chainrings). In the end, here is what I gathered (you can consider this a dream list):

Frame: Scott scale (either 600 or older 899) incl. seatpost – 899 grams
Fork: RockShox SID world cup tuned – 908 grams
Crankset+BB: Lightning carbon with extralite chainrings – 482 grams
Cassette: Nino’s titanium 10 speed 11-32 cassette – 172 grams
Chain: Yaban SL210, 96 links – 189 grams
Front derailleur: BTP carbon with carbon screws and clamp – 37.5 grams
Rear derailleur: BTP carbon – 103 grams
Shifters: Nino’s 10 speed grip shifters – 92.4 grams
Cables: Gleitec U3 + Power cordz cables – 50 grams
Wheelset: Extralite Turbotreme – 875 grams
Skewers: Tune skyline time trial skewers – 17 grams
Tyres: Maxxis maxxlite 285 kevlar – 570 grams
Tubes: Eclipse bicycle tubes – 112 grams
Pedals: Poshbike aerolite pedals – 74 grams
Brakes: KCNC X7 including titanium bolts and 140/160 rotors – 501 grams
Rotor bolts: MT Zoom premium rotor bolts – 14.4 grams
Seatpost+saddle: Poshbike specialist – 120 grams
Headset: M2racer lite w/ schmolke cap – 36 grams
Expander plug: Extralite ultrastar 2 – 6.9 grams
Stem: Extralite UL3 – 81 grams
Handlebar: Schmolke carbon MTB – 65 grams
Grips: Procraft superlite grips – 8 grams

Total weight: 5413.2 grams! The price would, though, be very high – I calculated around 9-10 thousand euro. Sorry, I could not find all the links. If you know of any kind of improvement on a component (i.e. a lighter component), please let me know so I can update this list.

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