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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

Recent Threads

[Bike] Aliexpress Cycling Tops

[Computing] Change to ssh handling of multiple identities?

[Bike] Endura Hummvee Lite II

[Computing] Marble Based Logic

Sanity Check For Nuclear Launch

Entropy and Life

[Link, Bike] Cheap Cycling Jerseys

[Link, Music] Music To Steal 2017

[Link, Future] Simulated Brain Drives Robot

[Link, Computing] Learned Index Structures

[Bike] Exercise And Fuel

[Maths, Link] Dividing By Zero

[Book, Review] Ray Monk - Ludwig Wittgenstein: The Duty Of Genius

[Link, Bike, Computing] Evolving Lacing Patterns

[Jam] Strawberry and Orange Jam

[Chile, Privacy] Biometric Check During Mail Delivery

[Link, Chile, Spanish] Article on the Chilean Drought

[Bike] Extended Gear Ratios, Shimano XT M8000 (24/36 Chainring)

[Link, Politics, USA] The Future Of American Democracy

[Review, Books, Links] Kazuo Ishiguro - Never Let Me Go

[Link, Books] David Mitchell's Favourite Japanese Fiction

Recent Replies

Now Is Cat Soft LLC's Chance To Save Up To 32% On Mail

Call Center Services for Cat Soft LLC

Solo Air Equalization

Update: Higher Pressures


Continental Race King 2.2

Removing Lowers


Mass Hysteria


Update: Lower Pressures

Farellones Bike Park

Update: Second Ride

Chutney v6


C++ - it's the language of the future

Learning From Trump



Oh Metafilter

Prejudice Against The Rurals

© 2006-2015 Andrew Cooke (site) / post authors (content).

[Bike] Servicing Shimano XT Front Hub HB-M8010

From: andrew cooke <andrew@...>

Date: Tue, 3 Apr 2018 07:45:13 -0300

A quick note because the dealer's manual is unclear, and there's a lot
of confusion on the 'net (every hub being slightly different).

These have caged bearings (plastic cages; lighter on the smaller disk
side).  That means that you have to remove the seal to get the
bearings out.  The seal comes out fairly easilly if you prise with a
broad screwdriver - try a few different spots around the rim until it
pops out.  I have had no problems doing this twice now.

Push the seals back in with your thumbs.

Also, only one cone unscrews (with the 22mm flats, non-disk side).
The other end stays on the axle which pulls out to give access to the
seals / bearings.

Other than that, easy as pie to service.  Lovely hubs.


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Previous Entries

For comments, see relevant pages (permalinks).

[Bike] Aliexpress Cycling Tops

From: andrew cooke <andrew@...>

Date: Tue, 27 Mar 2018 16:36:15 -0300

This is a list of cycling clothing I have bought from Aliexpress - the
aim is to collect together sizing information for my own use and also
to provide some guidance to others.

For a discussion of how Aliexpress clothing differs from more
expensive equipment, see

I'm 143cm (5'8"), 64kg (140lb).  50 yo.  Fairly decent shape (gym
regular; no six pack, but no belly either).  Chest measures 94-96cm
(not sure how tight the tape should be).


Miloto (thin, short sleeve, full zip, summer top) - actually bought
from Amazon (for $22), but shipped from China and available in many
Aliexpress stores (from $13).  Asymmetric coloured triangles on black
background (design slightly different from advertised - more text on
one shoulder).

Size S (92cm, measured 96cm).  Close fit (slightly stretched across

Basic cut, but well made with vibrant inks that haven't faded over
several washes.

51 days delivery via China Post.
[example url - not actual store]

No-name Morvelo knock-off from A+Service Store on Aliexpress for $16
(thin, short sleeve, full zip, summer top).  Light blue, green and
black bands with text.  Design is "retro" and original Morvelo was
probably in subdued / aged colours, but this is very bright.

Size M (98cm, measured 99cm).  Normal fit (not tight, but not baggy

Basic cut, with several loose threads, but vibrant inks haven't faded
over several washes.

17 days delivery via 4PX (Aliexpress).
[select third shirt - black/green/blue]

Spexcel from Spexcel Official Store for $20 (thin, short sleeve, full
zip, summer top).  Flower print on black.

Size M (94cm, measured 98cm).  Loose fit (very slightly too large).

Different fabric to others - more stretchy - which would have been
good on a tighter fitting jersey, but with the loose fit the rear
pockets sag and everything feels a little floppy.  More detailing
(cuffs, collar, plackett), well made.

66 days delivery via SF Express.

Jiashuo from Jiashuo Official Store for $23 (thin, long sleeve, full
zip, spring/autumn top).  Coloured bands from dark blue to white.

Size S (93cm, measured 94cm).  Normal to loose fit (sleeves lightly

Like the design - I think it's original, looks very clean.  Basic cut,
but well finished with no loose threads.

44 days delivery via 4PX.

Spexcel from Spexcel Official Store for $29 (fleece, long sleeve, full
zip, winter).  Black w black stripes.  

Size M (94cm, measured 94cm).  Normal fit.

Surprisingly thick / warm and still stretchy material.  Decent length
sleeves.  Good detailing (full inner placket, top of zip fits in
"triangle", zippered chest pocket; zippered rear pocket).

63 days delivery via SF Express.

Spexcel from Spexcel Official Store for $23 (windbreaker, long sleeve,
full zip).  Black.

Size M (96cm, measured 96cm).  Normal to loose fit (good for going
over something and wouldn't want to be tighter because front doesn't
stretch - see below).

Interesting design.  Very lightweight, either (windproof) nylon or
stretchy gauze - gauze on side panels and upper back to allow fit
while cycling.  No pockets.  Very simple, clean, windbreaker.

63 days delivery via SF Express.

Runchita from For Your Service 508 Store for $24 (thin wool mix; long
sleeve; half zip; spring/autumn top

Size M (90cm; mesaure 88cm).  Tight fit (size reocmmended by store for
weight / height; should have used measured sizes and gone with L).

Very good quality.  Nice material (natural feel) with good details.
No pockets and half zip, so not really a cycling top.  Stripe on front
is printed (and not reflective afaict) - does not match cloth stripe
on back.

22 days delivery via 4PX.


Thin, short sleeves
 Miloto   $22  S/92/96cm  51 days  Close fit   
 No-name  $16  M/98/99cm  17 days  Normal fit  Bright coloured Morvelo
 Spexcel  $20  M/94/98cm  66 days  Loose fit   Stretchy, slow delivery

Thin, long sleeves
 Jiashuo  $23  S/93/94cm  44 days  Normal / loose fit.
 RUnchita $24  M/90/88cm  23 days  Tight fit   Great quality, too small

Fleece, long sleeves
 Spexcel  $29  M/94/94cm  63 days  Normal fit  Warm, nice details

 Spexcel $23  M/96/96cm  63 days  Loose fit   Light / compact

Avoiding Copies

Many shirt designs are copies of products from other companies.  You
may not care, but if you want to avoid these, here are some tips:

* Anything featuring the figure 6 is probably Twin Six

* M??rvelo often include their name in the design.  They also have a 
  distinctive zig-zag logo (often on the rear pocket)

* Void often include their name in the design

* Gobik Wear designs often include the text "the custom wear company"

* Rapha often feature either "Rapha" or "RCC"

* Al?? have a distinctive logo that is the stylised company name

* MAAP designs often include MAAP in fairly small letters

* The Black Sheep logo is a sheep's head silhouette in a circle

* This Is Cambridge often include a TIC CC logo

More generally, if a design features a particular word, google for
that word plus "cycle wear" and see if you get any hits (this would
have helped me avoid M??rvelo back in the day...)

Sometimes a shop displays several designs on a single page.  If you
recognise one as a copy then it's likely the others on that page are
also copies of the same company's designs.

Pay attention to all the details.  Even some normally OK brands have
occasional copies (for example, there are some Spexcel bibs stamped

There's also a grey area between a "direct copy" (including logo) and
a "similar design" (eg Spexcel v Rapha).

Related to the above, some brands seem to be "native" to Aliexpress.
For example, my impression is that Runchita and Miloto jerseys are
genuine (with original designs).

Santic is somewhat odd, in that it seems to be priced very high on
Aliexpress, yet sold lower on Amazon (perhaps not the same items).  My
partner bought a pair of their shorts and liked them, but I felt the
padding could have been better for the price.


* All "delivery" times are from placing order to receiving parcel.

* SF Express have the shittiest most unreliable tracking.  

* Given the possibility of copies / fakes, any "make" is only a guess.

* Measured chest is twice width under armpits when laid flat.  I don't
  have an explanation for why measured width and fit aren't more
  closely correlated.



[Computing] Change to ssh handling of multiple identities?

From: andrew cooke <andrew@...>

Date: Thu, 22 Feb 2018 16:53:19 -0300

Just in case anyone else has hit this (only applicable if you have
multiple github accts and use the HostName hack to select keys).

I have multiple github accounts (personal use and work), and each has
a separate ssh key.  This is described at

And that has always worked fine, until today.

Today I saw:

  > ssh -T git@...-isti
  Hi andrewcooke! You've successfully authenticated, but GitHub does not provide shell access.

which is WRONG.  with and the "trick" above, I should
be identified as andrewcooke-isti (and so cannot clone or pull or push
to any work code...)

The fix is to add "IdentitiesOnly yes" to the ssh config:

  > cat ~/.ssh/config

       User git
       IdentityFile ~/.ssh/id_rsa-isti
       IdentitiesOnly yes

I have no idea what changed (could this be OpenSuse config specific?),
but hopefully this will save someone else the pain of debugging...



[Bike] Endura Hummvee Lite II

From: andrew cooke <andrew@...>

Date: Mon, 12 Feb 2018 10:58:06 -0300

Just received a pair of these shorts in the mail.

The old model were my main cycle shorts for years (I think I have four
pairs kicking around somewhere).  They're tough, comfortable, and
relatively cool in the heat.  More recently I've switched mainly to
bibs, but I still wanted a pair of shorts for the occasional ride and
also for the gym, and the old ones were really starting to show their
age (as well as suffering a few rips from falls over the years).

The main idea of the Lite was that they're for hot weather, so use
thinner material, although the seat of the pants remains something
thicker so they don't wear out.  That hasn't changed, but the look of
the material has improved - the grey colour I bought has a visible
texture like a natural fibre (my old light grey ones were obviously
nylon).  They also have a blue highlight (the pocket zip - more on
pockets below) that I guess looks more modern (not sure I'm a fan
myself, but it's a small detail).

Another change is the use of a button at the waist rather than snap
fasteners - probably an improvement, although (for me, at least) the
fasteners stayed closed fine on the older model.  The clickfast liner,
also using snap fasteners, remains as before.

But the two biggest changes are pockets and legs.

The cut of the legs is noticeably thinner, but they no longer have the
velcro width adjuster.  That's probably a good thing - they were so
wide they tended to get caught on my pump (mounted on the down tube)
at times, while tightening them with the adjusters looked really
(really) dumb.  But could this mean they are less cool when riding?

The old style had two leg pockets (one larger than the other).  The
new style has one leg pocket and one rear pocket.  A rear pocket is a
good idea - the leg pockets flapped annoyingly if you carried
something heavy like keys.  BUT the leg remaining leg pocket is
smaller than the old large pocket.  That means that you can no longer
fit a quarter-folded sheet of (letter) paper in there (maybe I am the
only person who takes print-outs of maps and routes on rides?).
Hummvee are generally well-known for their pockets, so this seems like
a step backwards.  Keeping both leg pockets and adding an extra at the
rear would have been better.

I've not ridden with these yet, but overall I think they're probably a
slight improvement.  The new fabric certainly looks nicer, and the
narrower fit is probably more practical, even if I wish there was
still a large leg pocket.



Sanity Check For Nuclear Launch

From: andrew cooke <andrew@...>

Date: Sat, 10 Feb 2018 17:44:38 -0300

  My suggestion was quite simple: Put that needed code number in a
  little capsule, and then implant that capsule right next to the
  heart of a volunteer. The volunteer would carry with him a big,
  heavy butcher knife as he accompanied the President. If ever the
  President wanted to fire nuclear weapons, the only way he could do
  so would be for him first, with his own hands, to kill one human
  being. The President says, “George, I’m sorry but tens of millions
  must die.” He has to look at someone and realize what death is—what
  an innocent death is. Blood on the White House carpet. It’s reality
  brought home.

  When I suggested this to friends in the Pentagon they said, “My God,
  that’s terrible. Having to kill someone would distort the
  President’s judgment. He might never push the button.“



Entropy and Life

From: andrew cooke <andrew@...>

Date: Sun, 4 Feb 2018 19:23:15 -0300



[Link, Bike] Cheap Cycling Jerseys

From: andrew cooke <andrew@...>

Date: Thu, 4 Jan 2018 20:13:58 -0300

I just received this jersey from Amazon and it seems pretty good (nice
fit, vibrant colours - no idea how durable yet)

But then I realised that teh same jerseys are available cheaper on

Here are my favourites so far (I should get a Pinterest):
(but select the dark one with a pink stripe).
(and, same link, select the grey/green/blue one; also maybe the light
blue one).



[Link, Music] Music To Steal 2017

From: andrew cooke <andrew@...>

Date: Sun, 17 Dec 2017 12:18:23 -0300



[Link, Future] Simulated Brain Drives Robot

From: andrew cooke <andrew@...>

Date: Tue, 12 Dec 2017 08:42:24 -0300

A simulated worm's brain drives a robot.

I have been re-reading William Gibson's work.  This just seemed so on
the money.



[Link, Computing] Learned Index Structures

From: andrew cooke <andrew@...>

Date: Tue, 12 Dec 2017 08:41:20 -0300

(frankly I think this paper i smore important than credited in that
discussion - we'll see...).



[Bike] Exercise And Fuel

From: andrew cooke <andrew@...>

Date: Sat, 9 Dec 2017 15:40:35 -0300

"Fuel" rather than "Nutrition" because I am thinking mainly about the
calories.  The following thoughts were prompted by a paper I read
online which I can no longer find - repeating the search leads me to
other, more complex studies.  So not only do I not have a reference,
but what follows may be oversimplified.

Glycogen v Fat

When exercising aerobically we burn fuel from three main sources:

 * Fat reserves, which are virtually unlimited (for most of us), but
   slow to access.  Fat reserves are stored throughout the body.

 * Glycogen reserves, which are limited but easier to access.
   Glycogen reserves are local to the muscle being used.

 * External sources (ie eating).

At low exertion levels the body preferentially burns fat.  But as the
power output increases this cannot be accessed quickly enough and the
proportion of glycogen increases.

Since the amount of glycogen is limited this explains "bonking" or
"the wall" - the unpleasant experience of glycogen reserves being
depleted.  As you would expect, this can be postponed by:

 * Lowering power output (and so reducing both absolute and relative
   burn rates for glycogen)

 * Increasing glycogen reserves.  Either via training or carb-loading.

 * Eating while exercising.  An external source of fuel will displace
   the need for glycogen / fat burning, but is limited in volume (you
   simply can't eat that much while exercising) and delayed (it takes
   time to digest what you eat).

Given all the above it is clear that the need to eat while doing
endurance exercise will depend on both the size of glycogen reserves
and the power levels required - both of which can vary strongly from
person to person.

Glycemic Complexity

One factor briefly mentioned above is digestion time.  High glycemic
index carbs are those that are easy to digest and provide a large
amount of energy for a short time, while low index carbs are slow to
digest, providing a lower, more extended boost.

Curiously, the index doesn't match the difference between simple and
complex sugars: white bread (starch) apparently has a higher index
than sugar (sucrose).

This is important for me because, it turns out, the time I stop riding
to eat is quite significant in how well I perform (over longer
segments on Strava).  So I guess I should look eating porridge before
a ride...