A column.
I once had the chance to talk with an overseas keyboard designer about the key travel I prefer.
I generally prefer around 2.8–3.4 mm.
Personally, this key travel feels right to me, regardless of whether the switch is MX-compatible or low-profile.
KawamuraMany Kailh Choc V2 switches have 2.8 mm of key travel.
I also prefer shorter travel in Cherry MX-compatible switches.
These are often called “speed switches.”
As we talked, something I’d vaguely sensed for a while started to catch my attention.
Could there be some kind of compatibility between key travel and the shape of a keycap’s top?
More specifically, I think the link between the two may be “typing style.”
This time, I’ll explore that idea a little further.
Is Low-Lift Typing Related to Short Key Travel?
When typing on a laptop keyboard, many people probably move to the next key without lifting their fingertips very much.
Sometimes they slide their fingers while keeping them in contact with the keycaps; other times, they lift them slightly and move along a nearly horizontal path.
Here, I’d like to define both as “low-lift typing”.
What caught my attention was the relationship between this finger movement and key travel.
Let’s take a standard CHERRY MX-compatible switch with “4.0 mm travel” as an example.
If adjacent keys start at the same height, pressing one all the way down creates a 4.0 mm height difference between it and the top of the key that hasn’t been pressed.
With 1.5 mm of travel, that height difference would be 1.5 mm.
Of course, if you release the pressed key and lift your finger well clear before moving to the next one, this height difference doesn’t necessarily become an obstacle.
But with shorter travel, the difference between the pressed position and the key’s original position is smaller.
If a keyboard makes it easy to type without moving your fingers far up and down, it should also suit a low-trajectory finger movement—in other words, a low-lift typing style.
KawamuraFor now, I’ll set aside the “actuation point.”
The assumption here is that keys are pressed all the way to the bottom.
That brings us to the shape of the keycap top.
Let’s imagine a keycap with a very deep dish.
Depending on the direction you slide your finger, you may need to lift it out of the dish before moving to the next key.
A flat keycap, on the other hand, lets you slide straight across.
Many laptops today use scissor switches with extremely short key travel, and their keycaps are almost always flat.
The tendency to pair short travel with flat keycaps may not be purely a matter of appearance or thinness.
Considering Three Keycap Shapes Through the Direction of Finger Movement
In an article for PFU’s “HHKB Life” that I contributed, I explained keycap shapes.
As mentioned there, keycap tops can be broadly divided into three types: flat, cylindrical, and spherical.
Flat keycaps have the familiar level surface seen on Apple keyboards, for example. Their tops are less likely to get in the way of fingertip movement in any direction.
Cylindrical keycaps are exemplified by the Cherry profile. They are curved mainly from side to side.
Spherical keycaps, found in profiles such as SA, have dips in both the front-to-back and side-to-side directions, giving the fingertip a sense of settling into the center.
In terms of tactile guidance for finger placement, flat tops provide the least, while spherical tops provide the most.
Cylindrical tops fall somewhere in between.
On the other hand, even spherical tops might offer both tactile guidance for finger placement and support for low-lift typing if their dips are shallow.
However, I think that may not hold true depending on the key switch’s travel.
Flat for Short Travel, Spherical for Long Travel?
Personally, I feel there is a certain compatibility between key travel and keycap shape.
With shorter travel, low-lift typing—moving the fingertips close to the surface—feels like a good fit, allowing the advantages of flat keycaps to shine.
With longer travel, you’re more likely to lift your fingertips and bring them down onto the next key.
In that case, the dip in the center of a spherical keycap can help you sense where your fingertip is.
As for cylindrical shapes, at least when they follow the original Cherry design, their curvature is not particularly deep. Personally, I find them relatively suitable for key travel of almost any length.
KawamuraFor these reasons, I mostly use cylindrical keycaps.
On the other hand, for a deep, clacky typing sound, I like tall spherical keycaps such as SA, MT3, and KAT.
It’s interesting that there are surprisingly few tall keycaps with flat or cylindrical tops.
Thinking about typing sound too would send me too far down the rabbit hole, so I’ll leave that aside for now.
Seen this way, the three shapes can be arranged from short to long travel in this order: flat → cylindrical → spherical.
Of course, this does not mean one shape is better than another.
In actual typing, sliding and lifting movements are mixed, and typing style is not determined by key travel alone.
Even so, a keycap is both “a surface for pressing a key” and “a surface you touch when moving to the next key”, and I feel there is value in seeing it this way.
That said, I don’t want to claim that flat keycaps are better for shorter key travel.
Personally, I prefer keycap shapes that give my fingertips some sense of orientation over flat ones.
Reading the Ideas of Earlier Designers in the Shape of Their Devices
It’s interesting to look at typewriters and laptops through this lens.
Many old typewriters have round keycaps with raised edges.
The act of typing a character—in other words, a single keystroke—may have involved much more travel than modern typing.
At that travel distance, there may not even have been a concept of low-lift typing; people may instead have tended to target each key precisely and press straight down. The keytops may also have been shaped to “resist deflecting force applied directly from above.”
Laptop keyboards, by contrast, use low-profile switch mechanisms to keep the chassis thin, and the combination of short key travel and flat keytops has become widespread.
This is where I’m a little unsure. I get the impression that flat keytops were probably simply necessary because, with a folding design, the screen would otherwise touch them—not because flat keytops made low-lift typing easier.
Still, the low-lift typing style probably emerged as a result of this combination of a thinner design and flatter keytops.
Keyboard design changes how people type, and those typing habits are reflected in the next generation of products. It would not be surprising if the two were connected in this way.
Conclusion: It’s Interesting to Consider Keycap Shape and Key Travel
That concludes this column on the relationship between keycap shape and key travel.
There really are many interacting factors here, and other considerations could come into play too: how shape affects typing sound; switch characteristics such as linear or tactile; the actuation point; physical layout (row-staggered, column-staggered, or ortholinear); and the keyboard’s overall size.
There is clearly a lot of room for personal preference here, and a person’s “typing philosophy” is probably a major factor too.
It might be even more interesting to see switches selected and keycaps developed with these philosophies in mind.
What kind of keycaps and key switch travel do you prefer?
- First published:
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- Reporting method: None (original column)
- Sources and references: None (original column)
- Conflict of interest: Products provided: None; monetized links in this article: Yes (Amazon links)
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