A brief gallivant about the marketplace of ideas.

Category: Reference

Reference : Alexander Grothendieck and the 1988 Crafoord Prize

Related articles:

  1. Lettre d’Alexandre Grothendieck” (Le Monde, 1988-05-04).
  2. Letters from A. Grothendieck” (Mathematical Intelligencer, 1988).

Reference : Bicycle repair

I recently tried my hand(s) at some maintenance work on my bicycle, an old Diamondback mountain bike. The rear brake pads were routinely wearing down quickly, in large part because the rear wheel knocked (wobbled side-to-side on its axle) significantly (several millimeters), which turned out to be related to a chipped cone and missing (!) bearings in the back wheel… And while we’re there, might the internals of the freewheel be scrambled, too? And the cassette cries for a cleaning…


With Park Tool’s “Big blue book of bicycle repair” [1,2] and YouTube (videos linked below) as my shop masters, I did the following:

  • Replaced the bearings and realigned cones, lock nuts, etc. on rear axle [3,4]. A few remarks.

    Cone adjustment. My rear wheel is a quick-release (QR), and getting the cones and lock nuts set just right took many, many adjustments. In particular, if the cones and lock nuts are set too tight on the axle prior to tightening the QR, the compression from the QR mechanism will tighten the cones into the wheel even more, causing the wheel to not spin freely [5]. The rule of thumb for QR wheels from the Park Tool book is helpful: You want just a trace of knocking when the wheel is off the frame, and no knocking when the wheel is on the frame with the QR mechanism closed. At the end of the day, what I looked for was, when the wheel is on the frame with the QR closed, (i) there is no knocking and (ii) the wheel spins freely.

    Dust caps. Be gentle when removing and replacing the dust caps! On my bike, these turned out to be fragile, and I bent one badly out of shape. Fortunately, the dust caps don’t seem to touch any parts of the wheel inners — they sit off the bearings, and are just to keep debris out of the wheel inners — so so far the bent-up dust cap hasn’t caused me any issues. Though if it’s so bent up it falls out, then the wheel inners get clogged up, that would be an issue… The dust caps on my wheel seem to have a rigid outer ring, but the rest of the cap is bendable metal. When putting the dust cap back in place, gently tap around the edges, ideally with something soft (e.g., plastic), until the dust cap sits snug.

    Personal reference. On my bike, the rear axle shows 6 threads on either side, beyond the lock nuts.

  • Deconstructed, cleaned, and rebuilt freewheel and cassette [6]. Getting the freewheel off the wheel was the hardest thing I did. You need a special freewheel removal tool, you need a large wrench (go go Gadget torque!), and even then, you need upper body strength — the freewheel can be on there tight!

    Personal reference. The Shimano MF-Z012 cassette on my bike has 30 bearings on the outside and 40 on the inside [7]. All bearings appear to be the same size. One of the pawls seemed to be oriented backward.

  • Replaced all brake pads and brake cables [8]. Installing and adjusting the brakes went fast and smoothly for me.

    Personal reference. The cantilever smooth post brake calipers on my bike were installed with a Shimano link unit, which comes in different sizes. The A link unit — with a 7.0 mm rigid arm — is the correct size for my bike.

  • Retaped handlebars [9]. Pay attention to the direction of taping. You want the tape to rotate the same way as the rider’s hands on the handlebars, so that the rider’s natural motion will tighten, not loosen, the tape. On the outside of the handlebars, wrists tend to rotate outward (away from the rider). On the uppers (inside) of the handlebars, wrists tend to rotate down (toward the rider). Tape correspondingly.


  1. Park Tool’s “Big blue book of bicycle repair” at Park Tool.
  2. Park Tool’s “Big blue book of bicycle repair” at Amazon.
  3. Repairing a loose bike wheel — hub overhaul” by RJ The Bike Guy (YouTube, 2013-10-04).
  4. Knock knock, loose hub : Tech Tuesday #117” by Park Tool (YouTube, 2018-10-16).
  5. Very stiff rear wheel” (Bike Radar, 2011-07).
  6. Bicycle freewheel disassembly/assembly” by RJ The Bike Guy (YouTube, 2014-04-03).
  7. How many balls in a MF-Z012 cassette : Post #11 (Bike Forums, 2011-07-02).
  8. Brake caliper mounting & adjustment — cantilever smooth post” by Park Tool (YouTube, 2016-04-05).
  9. How to wrap handlebars for road bikes” by Park Tool (YouTube, 2016-01-07).

Reference : Apple’s Time Machine

  1. Back up your Mac with Time Machine” (Apple Support).
  2. Delete a file from your Time Machine backup disk” (Apple Support).
  3. What to do when Time Machine backup is full” by Karen Haslam (MacWorld, 2018-05-07).
  4. Here’s how to delete Time Machine backups” by Darina Stavniychuk (MacPaw, 2018-12-21).

Reference : Amazon pricing

Today’s selection of articles:

  1. Quick introduction to Amazon pricing strategies” by Monica Axinte (DataFeedWatch).
  2. Pricing perfection? Tearing down Amazon Prime’s pricing” by Patrick Campbell (Price Intelligently, 2019-08-13).
  3. Amazon changes prices on its products about every 10 minutes — here’s how and why they do it” by Neel Mehta, Parth Detroja, & Aditya Agashe (Business Insider, 2018-08-10).


Articles on narcissism:

  1. How to tell if your friend is a narcissist“, by Christina Carè (Medium, 2018-11-15).
  2. 5 early warning signs that you are dealing with a narcissist“, by Jessie Monreal (Pysch Central, 2018-10-08).
  3. Narcissistic personality disorder“, by Melinda Smith (2019-06).
  4. 3 steps to identifying a narcissist“, by Bill Eddy (Psychology Today, 2018-08-01).

Read : 2019-07-11

Today’s selection of articles:

  1. This lidar is so cheap it could make self-driving a reality“, by Alex Davies (Wired, 2019-07-11). The company Luminar claims its Iris lidar unit — soda-can sized, 2 pounds, 15 watts, 250-meter range — can be produced for “as little as $500”.

Reference : Retirement & Your 401(k)

Selected articles about what to do with your 401(k) plan(s) when you retire.

NOTE : I am not a financial planner, nor is this financial advice.

My take-aways (subject to my (mis)understanding):

  • In some cases, your employer may be willing to continue to manage your 401(k) for you [A.1].
  • If you move your money from your 401(k), moving it to an individual retirement account (IRA) or cousin Roth IRA — or some combination of the two — seems standard [A.1,2,3]. This “roll-over” should not require a fee — in fact, some brokers may actually pay you [B.5].
  • IRAs generally have more options (e.g., investment vehicles) and flexibility (e.g., payout options) than 401(k)s [A.1,2,3].
  • Roth IRAs are not subject to required minimum distributions (RMDs) [A.3].
  • Do NOT withdraw the money from your 401(k) [A.3]!
  • “60-day rollover” rule : Basically, lets you avoid taxes and penalties if you withdraw funds from a retirement account, provided that you redeposit the funds into another qualifying (retirement?) account within 60 days [B.2].

A. Most-helpful articles:

  1. What to do with your 401(k) when you retire“, by Andrea Coombes (Nerd Wallet, 2018-08-02).
  2. What to do with your 401(k) when you retire“, by Rodney Brooks (U.S. News & World Report, 2019-03-15).
  3. What to do with your 401(k) when you retire“, by Wendy Connick (Motley Fool, 2017-10-27).

B. Other articles:

  1. How to decide what to do with your 401(k) after you change jobs“, by Melissa Phipps (The Balance, 2019-05-01).
  2. What is a 60-day rollover?“, by Matthew Frankel, CFP (Motley Fool, 2017-04-13).
  3. What to do with your 401(k) money when you retire“, by Rodney Brooks (Forbes, 2018-05-27).
  4. How a 401(k) works after retirement“, by Claire Boyte-White (Investopedia, 2019-05-05).
  5. Rolling over a 401(k)? Consider the fees“, by Tim Parker (Investopedia, 2019-05-31).

Reference : Financial advisors

Articles (and podcasts) on financial advisors:

  1. Six mistakes people make when hiring a financial advisor“, by Eve Kaplan (Forbes, 2018-01-29). Key points : Good financial planners…Ask questions about your unique situation. Take a holistic approach. Give you references to contact. Clearly detail how they are paid. Are fiduciaries (BUT see the Stay Wealthy article and podcast below). Are honest about the uncertainty of portfolio return.
  2. 7 of the biggest mistakes people make choosing a financial advisor“, by Matt Wiley (Business Insider, 2019-03-28). Ask each potential advisor for references, and contact them! (Also, be aware that your advisor probably gave you names of people who will speak highly of her or him, so gird yourself and dig deep into respondents and their answers!) Understand how they are paid, as this helps identify possible conflicts of interest.
  3. 10 biggest mistakes to avoid when hiring a financial advisor” (Stay Wealthy Podcast, 2019-02-14). Fiduciaries are not necessarily fiduciaries all the time; ask potential advisors to sign a fiduciary oath. Good financial advisors ask lots of questions and focus on “comprehensive planning”, not just investments. There is no such thing as guaranteed return.

Reference : Southwest credit card

Articles related to the Chase-Southwest credit card:

The cards

  1. Should I upgrade to the new Southwest Priority credit card?“, by Brendan Dorsey (The Points Guy, 2018-08-16).
  2. Should I cancel my Southwest credit card? [2019]“, by Daniel (Upon Arriving, 2018-11-02).
  3. Keep, cancel, or convert? Chase Southwest Airlines Plus credit card ($69 annual fee)“, by Grant (Travel with Grant, 2018-12-19).

How to apply and redeem points

  1. Transferring Ultimate Rewards points to Southwest“, by Nick Ewen (The Points Guy, 2015-10-26).

Closing the credit card

  1. How to cancel a credit card“, by Fred O. Williams (, 2019-01-18).
  2. How to cancel a Chase credit card without calling” (Finder, 2019-05-24).
  3. How long should you wait to apply again for an airline card you closed?“, by Tony Mecia (, 2018-09-04).

Reference : Friendship bracelets

One could ask how we got here, but sometimes it’s best to just take where you find yourself as given and go from there:

  1. DIY friendship bracelets. 5 easy DIY bracelet projects!“, by SaraBeautyCorner (YouTube, 2014-09-14).
  2. DIY chevron friendship bracelet“, by simpleDIYs (YouTube, 2013-06-19).