Cannondale P-bone

P-bone is an extraordinary product, extremely sturdy in design.

An opportunity presented itself, so I went ahead and bought one because I didn’t have enough money to buy a suspension forks. There is one important difference between a suspension forks and a P-bone, P-bone bike gives you a special adrenaline rush, until you fall off the bike that is, which will happen a lot.

The product itself is made from aluminum pipes the likes of which one would normally find used in a bike frame. Steerer is made of steel and the whole thing weights only 900g. This is extremely lightweight for something that can withstand a Nuclear™ Blast®.

This is how the P-bone forks looked like when it was brand new, later on it got a bit charred. Smiley

The biggest flaw in this forks design is the missing disk supporter. You can see one of my inventions further down; a carrier which would enable me to break safely (without falling). I never made that idea into reality because I fell off the bike so hard I couldn’t walk for a while and was left with 3 huge scars to remind me of the fall. I broke nothing but I still decided to buy a different type of bike forks.

The first drawing of the disk break adapter.

The drawing of the adapter.

A drawing of of how the adapter should look like after being successfully mounted on the bike forks, in relation to hub and disk rotor.

Let’s get one thing straight right away, having a sturdy forks is a wonderful thing, it enables you to reach high velocities, but if you fail to use it correctly you won’t get a second chance. The forks doesn’t forgive or forget; it doesn’t allow for any mistakes to be made, it is painfully rigid. The pipes are completely vertical to the ground, and that is painfully rigid (literally). Your will feel shoulder strain from excessive use.

Although the adrenaline rush on a P-bone is amazing, one cannot escape the feeling that as soon as one hits a hole in the road, the problems will become apparent. One will not only fly over a cookos nest, but land in it. I tested it a few times on “Sljeme” (hill behind Zagreb) and I got pretty much seriously injured. You do feel great going downhill but as soon as you hit a hole, you’re in trouble. I must have fallen at least 20 times. One time I was driving downhill at about 40-50km/h when I hit a hole, I must have flown 10m through the air in a theatrical flight, entangled up in my bike, having its drive lodged into my left calf, and ended up lending in a pit. That wasn’t a pleasant feeling. Smiley By the way, some time after my fall I had a chance to observe one individual jumping down a 5m slide again and again, watching it requires having guts.

My personal “feelingfull” observation: You could do ok with this configuration, but only in a highly controlled environment (in a town, no holes on the ground) and a perfect driving technique, everything else would be considered too risky.

One other thing, in order not to foil the bikes geometry, I designed an adapter which is to be placed on the bike forks and thus elevate the bike frame to the appropriate height (the adapter itself weighs more than the forks because I made it from an axle I took from a tank).

I left the forks at home, even though I decided to sell it. It simply wouldn’t go away on its own… Smiley Since the adapter was made of steel it got permanently stuck on the forks so I left the whole thing as it was in case I ever needed it again. Smiley (Update 2006. – the forks found a new owner who still uses it.)

While using the aforementioned forks on a Cannondale CAAD3 bike frame I was driving a one-of-a-kind never-before-seen bike. It was a good feeling having a unique bike. Smiley I even had some of my posts removed from mtbr.com for writing about a non-existent bike… Smiley

The schematic for an adapter used to elevate the headset main ring (weightbearer).

The break adapter has to be constructed using a pipe which has to have an appropriate diameter and a rounded P-bone leg 2-3mm thick so that it doesn’t interfere with the rotor. You have to weld a piece of metal on to the one of forks legs, which has a hole the exact size of the disk break clamp. This piece of metal has to be fastened to the forks with 2 screws through a spiral made on the side of the mounting leg, plus – it has to be on the outer site. The whole thing is to be very rigid since you are supposed not to encounter any problems when fitting a rotor 203. The concept is laid out here, the rest is up to you. One other problem you might encounter is the fact that most of the machines used for turning have limited production capabilities and that the person operating them doesn’t want to spend too many work hours on your little project. The production of a very similar adapter would cost somewhere around 200-300kn (that’s about 40 euros, or 50 dollars). Please bear in mind that you really should supervise the entire production process (and know EXACTLY how the final product is supposed to look like once it is done), otherwise you might end up with a faulty product on your hands. The first adapter that had been done was faulty. I wasn’t there during the entire production process so the machine operator misaligned the headset ring which was supposed to fit on the crown of the forks… I mean, they did fit perfectly, but were unusable. Smiley In the end we used adapter #1 to hammer in the adapter #2 Smiley

You can use only a completely rounded forks leg with this adapter, anything else simply won’t fit. You could also weld the adapter on forks made of steel but you would have to take in consideration the tremendous force produced by the break disk.

A picture of the elevation adapter mounted on a bike.

This same adapter can be used on any rigid or suspension forks as a distancer for achieving the desired height, the only thing that can vary is the length of the adapter body. I think that any potential reader should customize this project to suit his own needs, I didn’t need any further customization myself so I haven’t thought one up but I was thinking about using a three piece system that would fit tightly – in that case you would be able to reduce the weight of the adapter by 50 to 70%. The core should be made of aluminum and the rest should be made of steel. You could also make it out of one piece of steel, with cavities, but that wouldn’t look so god.

P.S. The P-bone is definitely bullet proof, I never heard of a single broken or damage one.hehehe

Update 2006. – one more thing should be taken into consideration before starting with project like this: the amount of time, effort and money invested into project will surpass the cost you would pay if you waited for a bit and bought a catalogue quality product.

CSS image preloading, guide

If you would like to use this article or portions of it, please contact me. Also let me know if you have feedback, positive or negative. Smiley

CSS image preloading is a technique which you can effectively implement by using only XHTML and CSS. The results which you will achieve are superior to what can be done with JavaScript. This universal preload technique works even on older Internet browsers, and on those browsers that have JavaScript disabled or unavailable. By using CSS image preloading, you can select which images will be downloaded before all the other images on the web page. An additional good thing with this little “trick” is that your page’s accessibility levels will stay the same.

Funky camel Smiley Photo by Phillip Collier.

Why use preload?

Preloading is usually not a crucial technique, however, sometimes you really do need to preload some images using some of the techniques available. If you don’t, your page may not work correctly. The important elements on your web page may download too slowly and this could prove to be a problem for all the visitors who have slow internet connections. Bear in mind that most people still dial up with modems!

Defining the specific problem

Let us say for an example that you have a web site featuring several pictures of camels and a menu.

There are four main categories on the menu, and all of them are made by using large <a> tags which feature some bold white text and a nice background graphic used for achieving contrast, and all of these features are defined in the CSS file. The page also features several larger images of camels defined by using the <img /> tag inside the XHTML file.

Page elements load in the following order:

  1. XHTML
  2. CSS
  3. all of the images found on the site
  4. background images defined in CSS

The problem with CSS background images is that they have lower loading priority. When a user connected to the Internet with a dial up modem accesses the page, he won’t be able to see the white text found within the <a> tags, because not all the background images which are being used as a contrast background will load until everything else on the page has finished loading. This really is a problem, because the user cannot know that there is more to the menu, and that he should wait a bit for the background images to load (he can’t see text, because it is on the default white background – standard CSS property when background image is still not loaded or missing). What may happen is that the visitor may not be interested at all by the content of the page, and would perhaps prefer to go to another section of the site, which he can’t do because he can not see the complete menu. – All of the images still have not loaded, and consequently, all of the CSS background images have not yet loaded.

Camel couple. Photo by Mira Pavlaković.

CSS image preload

The images fetched from the XHTML file by using the <img src=”image.gif” alt=”Image description” /> have highest loading priority, and after they have been loaded, the images from CSS will load next. Furthermore, all of the images located at the beginning of the XHTML document will load first (even higher priority). The solution to this problem is to put four background images at the very top of the file, and then “un display” them:

body
{
background:white;
}
#preload img
{
height: 0; width: 0; border-width: 0;
position: absolute;
bottom: 0;
left: 0;
z-index: -30;
}

Bear in mind that you can’t use the display: none tag because some older web browsers will not load the images if they are styled that way.

You have to use the position: absolute tag to position the preloaded images on the bottom left of the page with z-index lower than that of the other elements found on the page. The reason for this is simple; the older browsers will display the images as little black dots appearing at the positions where they are called in the XHTML file. By using this simple yet effective method you will hide them beneath a white colored background layer. Bottom left is great place to hide something, because users rarely look that way. Smiley

You should also be able to drop the “height: 0; width: 0; border-width: 0;” line because of the background position, but I think the previous method is much more failsafe.

When using XHTML code, you are expected to place images intended for preload as close to the top as possible.

<h1>Site title</h1>

<div id=”preload”>
<img src=”img/bg_1.jpg” alt=”Camel BG1, PRELOAD” />
<img src=”img/bg_2.jpg” alt=”Camel BG2, PRELOAD” />
<img src=”img/bg_3.jpg” alt=”Camel BG3, PRELOAD” />
<img src=”img/bg_4.jpg” alt=”Camel BG4, PRELOAD” />
</div>

Images intended to be preloaded are located after the <h1>Site title</h1> heading tag. If you should load the page without any CSS, it will still look acceptable, and its title header / title of the page will appear on the beginning of the page. Images are further described by using comments (alt=”” description), so someone using your site in its naked form (without CSS) will be able to understand what those images are all about and it won’t bother them. Smiley One additional benefit is that the text-only users will get a clue on what this page looks like in all its glory. Of course, you can provide even more detailed comments with your images, by using longdesc=”” tags, if you find it appropriate.

If you want to control the print output of your page, then use:

<style type=”text/css” media=”print”>
#preload
{
display: none
}
</style>

This will stop preloaded images from being printed.

Other alternatives

You could still try to utilize JavaScript image preloading, but in my opinion the CSS image preloading method is a lot simpler, and it works across many different browser platforms. This method has been tested, and proved working on (23.07.2006.):

  • Microsoft Internet Explorer 5 / 5.5 / 6
  • Mozilla Firefox 1 / 1.5
  • Opera 7 / 8 / 9
  • Netscape Browser 7 / 8
  • Apple Safari 2

JavaScript preload (tutorials):

 

I hope you liked this little CSS image preload tutorial! If you have any comments, or a suggestion, contact me!

 

I would also like to thank Paul for some useful suggestions on improving this article.

Deep blue sky

The plane flew up with a loud engine roar. While the thin metal bird was ascending towards the skies, figures of people left down on the airport ground were rapidly shrinking. I felt a bit anxious about the whole thing. “I guess this is it, there is no turning back now” – I thought and laughed but then started enjoying the azure vista that surrounded us on all sides. I was ready for my first ever parachute jump.

Weeeeeeeeeeeeeeeeeeeeeee! Smiley Foto by Mario Kranjčić.

The bird men

I remember when I first flew in a plane; I was a kid and my father took me as a passenger aboard a plane full of skydivers. I cant remember much of what happened, but I do recollect myself constantly crying and that I did not understand why I was not allowed to go anywhere near the open door of the plane. I also remember how hot it was in the back of the plane and that there were other people there with us, backpacks on their backs, simply jumping out of the plane.

The entire experience made quite an impression on me, so that’s when I’ve decided that I wanted to give it a try one day as well.

My first skydiving attempt was when I was 6 years old. – I have tried jumping off the first story of the building where my grandma lived, using a self made parachute. I was lucky not to get hurt that time, but I did get banged up quite a bit and therefore decided to postpone my great skydiving plans.

Bird men

More than 15 years had passed since that time, during which I hadn’t been in contact with any divers or the parachutes. All of this changed one night when I was in the company of a seasoned skydiver. The atmosphere of the moment was magical. Ten of us were completely entranced listening to the skydiver’s stories in the semi-darkness of twilight.

Later on I frequently wondered how it was possible that this old man seemed to be so completely free and how, in contrast to him, we were somehow left stranded on the ground. It seemed to me that all skydivers were somehow transformed, changed by their lifestyle, becoming part birds, living different lives from the rest of us.

A sleepless night

There are basically two ways in which one can jump from a plane (wit a parachute, or without Smiley; you could take a class and get the necessary training or enjoy a tandem skydive. In the first case one has to undergo complete training and preparations for a jump. When you near the end of the training period you make a few test dives and finally you make a free fall dive. The other option is to take an instant dive. All you have to do is listen to 10 minutes of instructions and you are ready to skydive strapped to an experienced diver who will open the parachute for you and control it until you land.

The preparations are easy; the entire thing is done on the airfield from which you will later take off. Your diving instructor prepares you for the entire procedure you will go through from the moment you step on the plane until the moment you touch the ground.

Tandem parachute is bigger and stronger from the regular parachute. It is made especially for the purpose of two man tandem jumps. Both the jumper and the instructor wear special suits that enable them to stay securely fastened to each other. The parachute is located on the instructors back, and the passenger is left facing forward.

Preparing for a jump

Skydiving is a serious thing. The biggest problem was to actually get to the airfield. I slept very little the night before the jump and I dreamt about the entire thing – from getting on the plane to jumping out and into the endless void. The entire thing is a fantastic experience the likes of which you will never forget.

The jump

Things look different when viewed from aboard a plane. It was a fresh summer day and scattered all across the blue sky one could see fluffy white clouds. The old instruments aboard the plane, the reflections sun made on the yellow wing of the plane together with the view we had of the fields and of the buildings down below us, all of these things kind-of mixed together and formed a feeling of pleasure and relaxation.

Placed immediately behind me, sitting on his chair, was the pilot. Next to him was the cameraman who was supposed to take a photograph or two during the jump, there was yet another diver sitting to my left and right next to the door. One could feel a stream of cold air coming from the airplane door. Sitting across from me in the tail section of the plane was the man I was about to entrust with my life – my instructor.

He is an experienced diver and a hulk of a man with a solid sense of humor:

“Price? Don’t worry about the price; we will negotiate it on the way down!” he said.

We played funny stuff during the entire flight. It seemed to me that all veteran divers must have an inbuilt altimeter because they kept getting more and more cheerful as we reached higher altitudes.

I, on the other hand, got a bit nervous as we got to the point when we had to stop joking around and to actually descend into the multi kilometer depths. Another good thing about making a free fall jump is that you first have to get to the point (high up in the air) from which you will then start your descent, and that turns out to be a first class panoramic flight with an exceedingly dynamic return trip.

All of the sudden things started to pick up the pace. The motor suddenly went silent and the other diver jumped out of the plane. The instructor called me over so we could securely fasten one to other using the special straps.

Parachuters in the plane

Before I realize it, there I am standing at the door, above a distant ground (3km in the distance), thinking to myself “My god, you stupid idiot, what have you gotten yourself into?”, and in the next moment …………… WOOOOSH!!!

Free fall

Free fall is a fantastic experience.

The acceleration is so sudden that your adrenalin practically makes you faint. Reality suddenly fades away, as if your brain gets frozen by this unbelievable sense of freedom. There is nothing beneath you, nothing to the left or to the right of you. Everything around you is empty space and you are descending to the ground.

All you have to do is to try to experience it fully with your arms and legs spread wide as if trying to greet the winds rushing in on you.

Both the sun and the clouds quickly fade from the view as you make the jump, your parachute opens with a loud sound and in a second it slows your descent from going 200km/h to going 30km/h. After this you begin slowly floating and finally you make the landing. Now you can start using your unsteady feet to get home.

Tandem jump price wary amongst different countries. It usually goes from 100-1000$ per jump. I guess I have been lucky with only 950 kunas (about 180$). If you want to see how scared you really looked while you were making the jump, you can pay something in addition to the basic cost and the other diver (the one with the camera) will follow you on your jump and take photographs.