Pick a crank, any crank

There have been many attempts to quantify the ideal crankarm length for cyclists of different heights. At just under 6’7″ (2.0m) I’ve been particularly interested in this subject. I’ve ridden cranks from 170-200mm on various bikes over time, and broken several sets in the name of experimenting.

This CyclingTips article collects some of the research highlights, including one from 2002 which establishes that “mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling”.

In layman’s terms, that means that longer cranks at a lower cadence will have the same cost as shorter cranks at a higher one. This was confirmed in 2017 by a study that found that crank length didn’t alter metabolic cost, but cautioned that too-long sets could cause joint issues.

So in the end, as the CyclingTips article suggests, cyclists can feel free to choose a crank length based on what feels best to them. For me, that’s 195-200mm for hilly road rides to help with low-cadence torque; 180mm on the rollers for seated spinning; and somewhere in between for flat roads and off-road riding (where pedal strikes are a concern). Anything shorter–and even 180s when standing–feels like I’m Homer Simpson riding the clown bike.

Finding cranks outside the 170-175mm range is still challenging and expensive, but worth hunting down a pair to try, especially if you’re on the extreme end of the height spectrum.

Cosmic clock

For years I’ve had a memory of a video showing the rise and fall of a city, over hundreds of years, from the top of a nearby hill. In particular I remembered being stunned by the way an entire civilization would appear like a blip, to an observer with a much longer timespan.

I’ve searched for a long time and finally found it; a clip called Cosmic Clock by Al Jarnow, originally shown on 3-2-1 Contact:

In my mind it was a rock on the hill; looks like it was a kid with a stopwatch instead. Thanks to Jason Kottke for the link!

Waking up

I think we didn’t evolve sleep, we evolved wakefulness – Paul Shaw

Happiness is what you make it

While negative events can cause ongoing unhappiness, “hoping for happiness from positive events appears misplaced.“. Oof.

On the plus side, it might be freeing to understand that waiting for that promotion/relationship/event won’t make a difference to your happiness. Embrace who you are and what you have today.

Reduce emissions, save a life

A new study estimates the mortality cost of our carbon emissions.

From The Guardian:

For every 4,434 metric tons of CO2 pumped into the atmosphere beyond the 2020 rate of emissions, one person globally will die prematurely from the increased temperature. This additional CO2 is equivalent to the current lifetime emissions of 3.5 Americans…

While it takes just 3.5 Americans to create enough emissions in a lifetime to kill one person, it would take 25 Brazilians or 146 Nigerians to do the same, the paper found.

While emissions are still something best addressed by government policy and economic incentives, and “carbon footprint” is a concept popularized by BP to shift blame to individuals, understanding the mortality cost grounds even individual decisions (including voting) with the opportunity to save lives.

The territory to be mapped

It’s more like the job of a science fiction writer is not to map the territory, but to point out that there’s territory to be mapped.

Science fiction is about pointing out that there are things that are out of the frame [in real life] that don’t properly belong out of the frame, whose ruling out is arbitrary—or customary, which is another way of saying the same thing.

Intelligence as skill acquisition

The intelligence of a system is a measure of its skill-acquisition efficiency over a scope of tasks, with respect to priors, experience, and generalization difficulty. – François Chollet, On the Measure of Intelligence

The road to wisdom

The road to wisdom?
— Well, it’s plain
and simple to express:
and err
and err again
but less
and less
and less.

Hope is hard

This is a wonderful way to explain why being hopeful and trying to change the world is hard, from climate scientist Kate Marvel:

Hope is not comfortable. It demands things, drains you, makes you sad and anxious. Hope is the knowledge that we can prevent bad things, and the realization that we might choose not to.

If something is guaranteed to happen, you don’t need hope. That’s faith:

Now faith is the assurance of things hoped for, the conviction of things not seen. – Hebrews 11:1

Hope is for when you’re gonna have to work for it.

How Superhuman sells behavior change for $30/month

Superhuman is the new darling of Silicon Valley and productivity geeks worldwide. They promise “the fastest email experience ever made” and showcase testimonials from prominent customers citing how much time it’s saved them and how it’s made them more effective. This has led to a waitlist of thousands and a customer base willing to pay $30/month for access to their app.

Despite the attention, there is still confusion about why Superhuman has been successful so far. The main reasons people cite are the elegant design, UI responsiveness, and “exclusivity” factor. But I believe their success comes from a clever set of techniques that combine to change the behavior of their customers.

Not just a pretty face

Since its early days, Superhuman has been criticized as “just a collection of browser extensions” with “a pretty UI” (the ultimate faint praise for designers). After all, behind the scenes it still uses Gmail (and only Gmail–no Outlook or other services are yet supported) to do the heavy lifting of sending, receiving, and storing emails, as well as filtering spam. Unlike the newer Hey service, Superhuman doesn’t change the basic mechanics of how email works–anyone can still email you, and you still deal with messages one at a time.

Superhuman’s interface (originally concepted with Ueno) is certainly elegant, packing a lot of information and power while still feeling simple and lightweight. Their keyboard shortcuts, and especially the CMD-K master shortcut (introduced with a clever interactive tutorial) are efficient and let them simplify and eliminate the visual clutter of buttons. The context panel updates to show helpful information about message senders and your schedule. And their dark mode is one of the best I’ve seen, good enough that I use it all the time. There’s certainly room to criticize (lack of visual contrast is a common issue), but overall it lives up to the “premium” design bar that their marketing promises.

The app is also very responsive. Superhuman makes offline access first-class, feeling like a native desktop app despite being built on web technologies. They promise “the fastest email experience ever made” in their marketing, and back it up with detailed engineering optimizations. Gmail has always prioritized speed, but Superhuman–especially with their desktop app focus–makes it significantly faster.

In theory you can combine a few browser extensions and settings (Simplify, Flash, Clearbit, Gmail offline, Mixmax, etc) to simulate the Superhuman experience. I think the packaging Superhuman has done is a significant improvement, and lots of extensions are likely to torpedo your UI responsiveness, but the basic features are available cheaper (or free) elsewhere.

The team has indeed built a beautiful interface to email, with clever interactions and impressive responsiveness. But Superhuman’s slick UI hides the fact that what they really sell is behavior change.

Superhuman’s behavior change techniques

Some former Superhuman customers have said that the biggest value they got from the app was changing their workflow. Superhuman is designed around the belief that you should empty your inbox every day (“inbox zero”) and most of its features and tips are aimed at helping you do that. Many people (and apps) have tried to implement the inbox zero philosophy, but most find it too difficult to continue.

While that can be used as a criticism (“You don’t need the app, just change how you do things”), it’s actually much harder to change someone’s behavior than to simply help them with their current behaviors. Entire professions exist to help people change their behaviors, and even they struggle to make a lasting impact. Email is a daily activity for billions of people, and for “an app” to change your behavior around it is an impressive achievement.

Superhuman combines a number of behavior change techniques to help ensure that you change your behavior and stick to it.


  • Superhuman requires a personal referral to even sign up (which you probably have to ask someone for, using your social capital)
  • Every new user is required to attend a (video) getting started call with a Superhuman employee (committing your time)
  • Part of that call is a step-by-step process to get to inbox zero before you hang up.
  • They also ask you to move the app icon into your dock (and hide your “old” email app icon once that’s done)
  • And of course, they ask you to pay, up-front, setting the expectation that “this is valuable”

All of these contribute to the commitment effect which keeps you invested in continuing the behaviors long enough to become your established workflow.


  • The name “Superhuman” itself signals that this is a product for above-average, important people. Of course you fit into that category, right?
  • Their “Sent from Superhuman” email signature on by default. You don’t have to pay to remove it (you’re already paying!) which frames it as a “feature”, rather than a “tax”. And as someone who values their time, wouldn’t you want to make that clear to others?

These aspects build up the social identity of the user, one of our most powerful motivators, and tie it to attributes of the Superhuman product. You can’t stop now–you’re superhuman!


  • Your personal onboarding contact follows up with personalized checkins after one day and one week, to see how you’re doing and help you stay on track to making Superhuman a habit (one quote: “Have you opened Gmail since our call? If so, how come? 😢”)
  • You get daily, personally-addressed emails from CEO Rahul Vohra for 30+ days
  • They show you a pretty picture when you get to inbox zero. Plenty of people tweet this out as a #humblebrag.

The more that Superhuman can reinforce your new behaviors, the stronger they become. Video games are the gold standard for this; think about all the “Level up!” and “Achievement unlocked” celebrations a typical game employs. Vohra regularly speaks about how they use game design techniques to build Superhuman.

The hidden feature

The first rule about behavior change…is you do not talk about behavior change.

One of the interesting aspects of Superhuman’s marketing is that they don’t mention behavior change at all. Their homepage is entirely focused on speed and product features; their tagline is “THE FASTEST EMAIL EXPERIENCE EVER MADE.” Despite the benefits of inbox zero and the value of the commitments in their process, neither of those things make the homepage.

In an interview, CEO Rahul Vohra noted that they draw their marketing copy from the testimonials of their happiest customers. So this focus on speed and product features is something that their customers share.

So why isn’t anyone talking about the new behaviors (besides the former customers mentioned above)? One theory is that nobody wants to change; they want to want to change. Telling people that they’re doing something wrong, and asking them to change, is rarely well-received.

On the other hand, telling people that they are good (and busy, and important), and that their current tools are holding them back, is flattering. Lots of people will identify with that kind of messaging, and reflect it back to others.

The combination of these techniques leads to a feeling that:

1) You are important and your time is valuable 2) The creators of Superhuman care about you and your success 3) You’re indebted to the person who referred you.

It’s a powerful combination, and one that I haven’t experienced from any other software application. The closest analogous experiences I can think of are a professional development course, a therapist, or a university education.

Why I paid

I’m not the target Superhuman customer. I don’t get all that much email, nor handle important, time-sensitive information that way. I don’t subscribe to their “inbox zero” philosophy. As a designer of productivity software, it’s interesting for me to see their design choices, but I don’t need to pay $30/month to do my email with Superhuman.

And yet I did pay them, for a long time, because I felt that by canceling I’d be disappointing Paula, Rahul, and my referrer David, who had all invested in my success. I’d have to move my old email apps back into position, and set up the shortcuts and extensions that I do use from Superhuman in another email client. I’d be admitting that my email messages aren’t all that important after all–and that maybe I’m not either =) And I’d miss those regular reinforcements that I’d done well at a difficult task.

So while I admire the beautiful design and speed of Superhuman’s apps, I was really paying for the commitment, signaling, and reinforcement techniques they used to change my behavior.

Changing apps is easy.

Changing yourself is hard.

Kudos to Superhuman for understanding the real challenge for their customers and designing to support them.