Need 29″ studded bike tires? Not that many options out there. I’m aware of:
- Kenda Klondike (2.1″, 400 non-sharpened spikes, 1464g)
- Nokian Extreme (2.1″, 294 sharpened spikes, 990g)
- Schwalbe Ice Spiker Pro (2.25″, 402 sharpened spikes, 1170g wired / 890g folding)
2 years ago I wanted my winter tires to be wider and was ready to pay for the higher-end lighter option, so I bought the folding Schwalbes.
They hold fantastically on ice and pull fantastically in snow or slush. One serious disappointment was that the scale showed 1040g, or 15% over the specified weight.
Now the second one. In just two winters, nearly all spikes from the central row of the rear tire have lost their hardened tips. The soft (probably aluminium) base squeezed down and became nearly flat, hidden inside the rubber knob. Some of the (former) spikes are pictured. It is relatively easy to replace the spikes, but I have a feeling that the rubber base is now weakened and the replacement drops out quickly.
The central row is probably not critical; two adjacent rows are in contact with the ground, and have lost just a few spikes. One must note that Kenda and Nokian just do not have that central studded row.
I had to replace a rear wheel before leaving for a longer group ride:
Drive-side spokes were tightened to 100Kg, which was just barely enough for non-drive side not to go slack.
That was the most prominant crack, but not the only one – in fact, all drive-side sockets have developed smaller or bigger slits:
This was an ultralight-class wheel with 24 spokes and under 400g rim. Weight-limited to 80kg, which I fit in, but without any reserve, has served me for some 10K kilometers. So I have decided not to send any claims to a vendor, but also not save on spoke number the next time – or use more meaningful 16/8 spokes.
754g, that is with stick-on rim tape.
Update: In just two weeks the pair front wheel collapsed in a small crash, so this ultralight wheelset does not serve me any more.
Suppose you are wondering randomly on a chessboard, starting from a corner, making one step up, down, left or right every time. You are not allowed to step on cells which you have already visited earlier. What are the chances that at some point you’ll not be able to go anywhere, i.e. you get caught in a dead end made by your own previous steps?
I got no idea how to solve this “purely”. Out of curiosity, I calculated the probabilities programmatically for 8×8 board for any path length (up to 63, naturally). Blue line shows the probability of being stuck at given path length or earlier, yellow line – 10 x probability of being stuck exactly at this path length.
Graphs do not show anything unexpected, except – what happens at points 48 and 49? I have no idea.
The calculation was straightforward by “first thought” without any optimizations. For each path length, I did 10^6 runs; with this amount, dispersion in the results between runs was by far under 1%, and run time acceptable (I do not indicate the units of the right Y-axis 🙂 )
Surprisingly I was not able to profile the run with gprof; looks like MacOS default C compiler and/or libraries just do not do it.
Still interested in a general solution, if there exists one.
LTE coverage around Helsinki. Left to right: DNA, Elisa, Sonera. Maps taken from official sites of the operators in January 2013.
I enjoy wandering around the countryside – also without planned route. Would be nice to mark roads, which are less interesting than others? For example, all dead-ends, and in general cut edges of the road graph.
Good that we have OpenStreetMap with open data and tools. I have created software to pre-render a given region (not too large one) with all cut edges marked. This is how it looks like, marking with thick blue dashed line:
Painted dead ends on OpenStreetMap
Storing and providing OpenStreetMap tiles requires a lot of disk space and bandwidth, so for now I only rendered small regions as a proof-of-concept. Welcome to peep at the maps!
Lubuntu 12.04 seems to have a problem: new keyboard layout can’t be added by graphical menu. Seems to go back to dark times of knowing, which config file to edit… You can add the “layout switcher” (right click on the panel -> Add / remove panel items -> Panel applets -> Add -> Keyboard layout switcher), but I was not able to add any new layout to that “switcher”.
Thanks noobish-nix for a solution. The
magic wordconfig file is
After @lxpanel line, add the line with your setxkbmap options, for example:
@setxkbmap -option grp:switch,grp:shifts_toggle us,ru,fi
Restart lxde (logout/login) to take effect.
There are lots of examples showing how to set a nice colorful bash prompt. I wanted more than the output: the typed text should be hi-intensity, but the command output should be normal. I found only a hackish solution:
- Install a DEBUG trap in your ~/.bashrc:
trap 'echo -ne "\e[0m" > $(tty)' DEBUG
- And add yourself to the tty group:
sudo adduser <username> tty
It works, although I still have to think what can it break at some moment (long after I completely forget about that .bashrc line):
Meanwhile, grc is a regexp-based colorizer for output.
I think I managed to give a full answer to question “Will shifter A and derailer B work with cassette C”. Or almost full. See the screenshot of the table below. If the meaning of these numbers is not self-evident, read explanations on the permanent page. Enjoy!
I have got a report that these two types of rear deraileurs have the same mechanical advantage:
- Shimano Dyna-Sys (which are marketed only as “10-speed”)
- SRAM E.S.P (which are marketed only as “9-speed”
Both take 35mm of cable to go over the whole cassette. Picture shows SRAM X.9 and Shimano XT, but any other derailleurs of the mentioned types would be interchangeable.
This means that either one can be replaced with another (provided that it can handle your biggest cog). I have not verified this myself. Remember that “SRAM 10-speed” deraileurs have different mechanical advantage, as do “Shimano 9-speed” ones, and there are no other pairs which are not designed for each other but work.
Maybe not a really useful finding in practice, but certainly an interesting one.
In August 2010, I made a fast 4-day cycling and bike-carrying trip over northeast Norway. Varanger peninsula, one of real “ends of the world”, is almost encircled by roads, the gap is “just” some 20 km. Here is the map, with the blue track following the roads where I was riding on my bike, and the red track showing the part where the bike was riding on me:
Report with photos here. I’m wondering how is it possible that I’ve been to that region already three times and I’m ready to select it for my vacation trip once again.
In Finland, most trains allow transportation of bicycles, but the fastest “Pendolino” trains do not.
Recently I traveled with my MTB, and Pendolino was the only feasible option (it was the first morning train, the next one arrived already too late). The only way was to partially disassemble and pack the bike so that it becomes normal luggage.
Packed bike in the room
Spring is coming to our corner. I skied on the Finnish Gulf today, and it might feel like it was last time this year. Steady +5 daily without negatives nightly deteriorates the sea ice.
The picture shows some of my recorded rides. I did not record the shorter ones. Even if the ice skiing season is over (which is a pity), it was a perfect one!
Sure, sometimes a picture can be worth a thousand words. Sure, not always (try for example to express this phrase with a picture). I enjoy nice visualizations… but this time I could not resist to laugh at a failed attempt to draw a picture which would be worth several words, or even just one word 🙂 Right, how would you picture “carbohydrate”?
The scan of a chocolate bar wrap shows its nutritional information. OK, I can guess that picture “kcal” in a circle stays for calories. Now, make your wild guesses, what’s the meaning of other circles. Practice your imagination and figure out what the designer tried to depict with so visual guides like . “Right answers” below the cut.
Nothing bad has happened to me because of this, and one may argue that targeted ads are better than non-targeted. But I do not like the idea of being tracked – and I shut off all web ads anyway with AdBlock. Additionally, I have NoScript always on (and allow sites selectively each time when “some site does not work”).
I have quite long “accept-language” header set in my browsers, as I can read web pages in several languages. panopticlick shows that I’m one such user out of about half million (it might be that I’m just the only one with this value of accept-language, who made a check there).
I’m not feeling paranoid because of this. But I’ll be happy to know, is there a way to pass my (complicated 🙂 ) language preferences without allowing for easy fingerprinting.
We have a beautiful, real winter here in Finland. The weather I just desire: stable negative temperature never creeping to zero, enough snow for any winter fun – about which I may blog more some time later. One of the cool things to do this time of the year is to ski, skate, walk or cycle over the frozen water. For example, last cold (or, better say, just normal) winter of year 2003 we cycled from the Åland archipelago to the continental Finland. When not going this far, I regularly ski around the Suvisaaristo islands next to which I live (recorded route here). Moving over ice is great!
But what if the ice breaks and you fall in the zero degrees cold water?
There is a simple answer: try this before it hits. Your chances to get out alive become higher. Read on for the boring theory and a short report of how I did this recently in a mild -17°C afterwork evening. Continue reading
Short summary of this post: HP Photosmart C8180 all-in-one printer works perfectly with Linux right out of the box.
This is my DIY ultralight water bag. The bag itself, without the bladder, weighs 20 grams.
Previously, I have tried to find “theoretically” the tooth counts of the Nexus-7 internal gear hub. Some nice numbers were obtained, but there were some suspects (you may think yourself what can be wrong with the numbers given in the link). Soon after, I disassembled the real hub and counted the teeth of all rings. Here are the real numbers. Continue reading
Vendors of internal gear bicycle hubs naturally give the transmission ratios of own products. But I was always curious how exactly these ratios are obtained, i.e. which planet gears are engaged in which combination and how many teeth each gear has. This information was surprisingly hard to find – in fact, the only vendor who discloses this is Rohloff! It is certainly possible to just disassemble the hub, but, you know, sitting half-day at the computer screen is more attractive nowadays 🙂 I have Nexus-7 hub on one of my bikes, and I have “reverse engineered” the exact tooth counts. Continue reading
Many math problems are fascinating. Often they are also difficult, so that only those who have high enough education can understand their beauty. But sometimes a really simple problem – such that anyone with just the elementary school knowledge can solve it – can be quite cute as well. Most elementary school math questions are truly boring, but it’s possible to add some spice to this mass.
1 (I knew this earlier) “Dried cucumbers”:
Cucumber contains 99% of water. A box of cucumbers weighs 100kg. During winter storage, cucumbers dried out so that they now contain only 98% of water. How much does the box weigh now?
2 (I got this today, which inspired me for this post) “Probability for doctors”:
Assume a test for a rare disease (which affects 1 person in a million) is 99.99% accurate. A patient tests positive. What are the probabilities he actually has the disease?