Archives for: February 2006

just like programming

posted by ben on 06.02.12 at 12:34, null, books, books, Leave a comment Permalink

"... A workman is planting stakes to make a fence. He plants them at such a distance from each other that the bucket of tar, in which he dips their lower ends to a depth of 30 centimetres, is empty at the end of 3 hours. Given that the quantity of tar which remains on the stake equals 10 cubic centimetres, that the bucket is a cyclinder whose radius at the base is 0.15 metres and whose height is 0.75 metres and is three-quarters full, that the workman dips 40 stakes an hour and takes about 8 minutes' rest during that time, what is the number of stakes and what is the area of the property which is in the form of a perfect square? State also what would be the number of stakes necessary if they were planted 10 centimetres further apart. State also the cost of this operation in both cases, if the stakes cost 3 francs a hundred and if the workman is paid 50 centimes an hour."

Must one also say if the workman is happily married? Oh, what unwholesome imagination, what depraved brain incubates those revolting problems with which they torture us? I detest them! And the workmen who band together to complicate the amount of work of which they are capable, who divide themselves into two squads, one of which uses one-third more strength than the other, while the other, by way of compensation, works two hours longer! And the number of needles a seamstress uses in twenty-five years when she uses needles at 50 centimes a packet for eleven years, and needles at 75 centimes for the rest of the time but if the one at 75 centimes are ... etc., etc. ... And the locomotives that diabolically complicate their speeds, their time of departure and the state of health of their drivers! Odious suppositions, improbably hypotheses that have made me refractory to arithmetic for the rest of my life!

-Colette, Claudine At School, pg 25

posted by ben on 06.02.10 at 21:45, null, seattle, Leave a comment Permalink

There's a hipster I've been seeing around town. He was at that loft party. He goes to the Bauhaus. He walks down the street. He puts some sort of goo in his hair so it sticks straight up. He always wears blocky black sunglasses and he's comically short. He's amusing to look at and I've finally realized why. He's a joke.

posted by ben on 06.02.09 at 16:09, null, seattle, minneapolis, 1 comment Permalink

There's a hipster here shaped like a pear. He has a drum and a suitcase made out of wood. I know he doesn't belong here and I wish he didn't belong in Seattle. I'd be willing to admit him to the city if he weren't shaped like a pear.

When I go back to the city, everyone should be young, beautiful and erudite. No one will wear sweat pants.

Everyone in Seattle will sit in coffee shops working on their pet art projects and falling in love. That's the way Seattle is. The people shaped like pears stay in where I don't have to look at them. It's so much better than Minneapolis. Oh, it will be so great to be back.

Comment from: Graham [Visitor] Email
Seattle may have hipsters with inconceivably tight pants, but Woodinville has greasers. Real ones. And they even like Rockabilly music and rat-rods. So there.
Permalink 02/11/06 @ 23:23

Fixed with Vertical Dropouts

posted by graham on 06.02.08 at 20:16, math, Bicycles, 8 comments Permalink

So I've been meaning for some time now to figure out a method for finding properly fitting chainring combinations to use on a fixed gear with vertical dropouts. This guy from the point83 forums claims to have one. Does this look reasonable to all you math/bike types?

OK, basic math...
Add the number of teeth on your chainring and on the rear cog. Take the total, and look it up.

40 = 0"+/- 1/2"
41 = 1/8" +/- 1/2"
42 = 1/4" +/- 1/2"
43 = 3/8" +/- 1/2"
44 = 0"+/- 1/2"
45 = 1/8" +/- 1/2"
46 = 1/4" +/- 1/2"
47 = 3/8" +/- 1/2"
48 = 0"+/- 1/2"
49 = 1/8" +/- 1/2"
50 = 1/4" +/- 1/2"
51 = 3/8" +/- 1/2"
52 = 0"+/- 1/2"
53 = 1/8" +/- 1/2"
54 = 1/4" +/- 1/2"
55 = 3/8" +/- 1/2"
56 = 0"+/- 1/2"
57 = 1/8" +/- 1/2"
58 = 1/4" +/- 1/2"
59 = 3/8" +/- 1/2"
60 = 0"+/- 1/2"
61 = 1/8" +/- 1/2"
62 = 1/4" +/- 1/2"
63 = 3/8" +/- 1/2"
64 = 0"+/- 1/2"
65 = 1/8" +/- 1/2"
66 = 1/4" +/- 1/2"
67 = 3/8" +/- 1/2"
68 = 0"+/- 1/2"
69 = 1/8" +/- 1/2"
70 = 1/4" +/- 1/2"
71 = 3/8" +/- 1/2"

As you can see, it repeats. Here's the notion, For each tooth you add, you "remove" a 1/4 of a link of chain (assuming you don't change the chain length and could actually remove 1/4 of a link). So if you add 4 teeth, you need to add a link to your chain. Pin to pin is 1/2", averaged out on both top and bottom is 1/8" and there you go.

So, if you know your dropout to BB is 14.5" center to center (BMX in this case), you can run a gear combination where the total number of teeth equals 40, 44, 48, 52, 56, 60, etc. The difference in length due to the chainring being larger than the cog is not worth calculating. Besides, chains wear.

Comment from: ben [Member] Email ·
I'm skeptical about this:

"The difference in length due to the chainring being larger than the cog is not worth calculating."

I'd just try whatever combinations you can with whatever you have around. And no brakes. Safety is for the weak.
Permalink 02/09/06 @ 16:03
Comment from: graham [Member] Email ·
That's the part that caught my attention also.

Yes, brakes are for girly-men. If there's ever a really steep hill I'll ride around it or walk my bike down.
Permalink 02/10/06 @ 13:31
Comment from: admin [Member] Email ·
That took me longer than it should have to figure out what the hell he was talking about. Ugh, "40=0+/- 1/2" meaning "40=0 mod .5". Whatever. Since pin-to-pin on a regular chain is 1/2" the number of teeth on a ring/cog is half the circumference in inches. Took me a while to figure that out too. Sigh.

I agree with ben that the difference between cog and ring should make a difference. I wrote something to compute total chain length, it's in ~/vertdrop/. Sample output:

Enter stay length in inches (c-to-c): 14.5
Enter number of cog teeth: 14
Enter smallest ring size (even number): 30
Enter largest ring size (even number): 54

cog: 14 ring: 30 chain length: 74.7368
cog: 14 ring: 32 chain length: 77.1819
cog: 14 ring: 34 chain length: 79.672
cog: 14 ring: 36 chain length: 82.2049
cog: 14 ring: 38 chain length: 84.7787
cog: 14 ring: 40 chain length: 87.3912
cog: 14 ring: 42 chain length: 90.0403
cog: 14 ring: 44 chain length: 92.724
cog: 14 ring: 46 chain length: 95.4403
cog: 14 ring: 48 chain length: 98.1871
cog: 14 ring: 50 chain length: 100.963
cog: 14 ring: 52 chain length: 103.765
cog: 14 ring: 54 chain length: 106.593

So, unless I'm retarded, the total length has to be slightly bigger than an integer so you can actually put the chain together... My numbers don't match up with his, ie 14+30=44 -> 74.7368 inches, which doesn't sound like it would work at all.

[edit: this was collin]
Permalink 02/10/06 @ 15:02
Comment from: Rodrigo Hernando de la Sosa [Visitor] Email
I think your chain length got messed up somewhere. That's one hell of a long chain.

For 50x16 gearing with a 14.5" stay, i get a ~45.65" chain. That's about 1/10" off from the chart (which has completely lost me by now) if I read it correctly.
Permalink 02/10/06 @ 18:02
Comment from: ben [Member] Email ·
I almost made it down the hill without walking. There were cobblestones. It doesn't count.
Permalink 02/10/06 @ 19:52
Comment from: graham [Member] Email ·
Permalink 02/10/06 @ 20:15
Comment from: ben [Member] Email ·
Ha ha. Let's see you do it...
Permalink 02/10/06 @ 21:13
Comment from: ben [Member] Email ·
It looks like the Bianchi is about 49.5" with a 50-18 and 15.5" for the stay. It's so depressing that a random stranger is riding something bigger than me. I hope you live somewhere flat Rodrigo Hernando de la Sosa... if you're from San Francisco, I'm going to be extremely depressed.
Permalink 02/11/06 @ 10:53
posted by graham on 06.02.07 at 23:57, Raves, null, Leave a comment Permalink

Graham bought an oyster knife.

posted by ben on 06.02.05 at 07:18, null, food, pictures, seattle, Leave a comment Permalink

new tom

posted by ben on 06.02.05 at 07:14, null, null, admin, Leave a comment Permalink

I'm just going to copy the old blog up to the new server for now. Porting to the new b2evolution alpha (by which they apparently mean release version) is an incredible pain. I'm still trying to get the pictures up from old tom, so until that happens there are going to be a lot of posts with missing pictures. Check the admin blog for further goings on.

In the meantime, it's safe to post again.

new tom (and dev below)

posted by ben on 06.02.05 at 07:12, null, pictures, minneapolis, 2 comments Permalink

Comment from: devin [Member] Email ·
Oooh, pretty.
Permalink 02/05/06 @ 12:15
Comment from: ben [Member] Email ·
That's a pair of miserable 10/100 switches at the bottom there. Why? I don't know. I'm so glad I bought modern servers to go in an antiquated data center...
Permalink 02/10/06 @ 19:56