This is great, I just saw your post on X. I'm also building a bike computer!
eInk is the right display tech. I think this will do really well. It might need a UV filter.
That said, I don't love needing a separate device (hence, I don't own any bike computer). This is just my preference, but I really prefer to just plop my phone on my handlebars. So I'm building a bike computer app for iPhone: https://x.com/mholt6/status/2090529441944687087 (trying to get Apple to approve my developer account / business info, but they're hung up on my website of all things).
Phones are definitely not ideal in terms of display and energy use, but, I have found that with proper optimizations, energy use is a non-issue. To offset display problems, the app has several ride modes: a rich map display with 3D road or satellite view; a high-contrast wireframe map that looks great at both high and low refresh rates because it has no analog-style gauges; an instrument panel dashboard view; and a voice-only mode that has big touch zones for on-demand voice updates, using a state of the art mobile voice synthesis model. For connected radars, the app also renders radar data and has a screen like Tesla/Rivian's autonomy displays.
The app automatically manages thermals by switching modes to preserve battery life.
In my testing so far, by managing energy, making really good voice feedback, and using high-contrast screens (every mode other than the "rich" map), even a dimmed iPhone display is quite a usable bike computer in high-altitude sunlight.
But man, that eInk looks so clean and nice. Definitely the superior display! Nice work and I hope to learn some things from it!
EDIT: Woah, you got ANT+ support using BLE radio? I am not surprised that that is possible, but dang, that must have been a clever LLM.
note using a phone mounted to a bike or motorcycle can cause damage over time to the camera assembly especially the motors used for OIS. depending on how much you ride or the quality of the roads you ride, it could be an issue.
your project does look amazing. sorry that the appstore team is holding things up.
RE: ANT+, a hackrf one and fable was key to the hack.
I use my phone as a bike computer too but it only works on short rides around town. Anything longer gets cooked by the sun until the screen dims and battery stops charging.
That’s why the head units in my bikepacking groups have screens that double as solar displays. The Coros Dura is probably the most popular one for all day or multi-day trips.
I used a transflective LCD. Works fine. You don't need UV protection nor have temperature issues. (Yes also build my own two years ago but I don't do pr so no slick website).
eInk does seem like an awesome choice for this to me too.
I've gone without a bike computer for the same reasons as not wanting a second device. I used my phone for years in a water proof front frame bag with a transparent cover. Usually for not more than 3 hours at a time. Only on my Pixel 7a did I end up with burn in from the Wahoo Android app's status screen, where "n/a" for not having a power meter ultimately burnt in after about 2 years, at least that's when I noticed it. Now I just go without being able to glance down and see ride stats or directions. More planning or stopping if I reroute is required, but I didn't want to damage the phone... :(
Presumably an app could cycle displayed screens, if that's what you meant by switching modes, to avoid burn in? But I really thought AMOLED was past that when I never saw it on previous phones.
To each their own and the e-ink computer is a neat project. But I'm personally with you on not wanting a separate device. I have my iPhone and a quad lock case I swap on for rides.
Not sure I'm 100% on board with the visual style of your interface (some of the metrics look like they'd be nearly impossible to read while riding 30mph down a gravel road) but I'd love to check it out once it's released.
Do you have a way to sign up for release email or updates for your project?
Thanks; not yet unfortunately, I have been too busy to set up a mailing list, but that's a good idea.
The video preview I linked to only shows the rich maps and instrument modes. There's also a wireframe map view that is higher-contrast and much more practical for your gravel rides: https://i.imgur.com/lZF20Xz.png -- and I am still tuning of course, we can make the map smaller and the characters larger, etc.
Maybe follow @mholt6 on X for updates when I have them... whenever Apple will let me in.
In my humble experience the gold standard for bike computer screens was the Wahoo Elemnt Roam 2. It had like 64 colors or so but you could see it everywhere.
That being said, seeing that there are now eink displays capable of 60Hz, I wish they (and projects like this one) could take over in this specific market.
eInk is like a piece of paper, which gets MORE visible in the sun, but standard touchscreen LCDs/OLEDs get harder to see. I am not sure about the physics/reasons for this. Phones also aggressively dim screens to conserve energy and lower temperatures. Phones absorb a lot of sunlight, so a white eInk display is brilliant in that regard.
Refresh rate is a solved problem for eInk as well, but it comes with energy tradeoffs and... might still be proprietary. But 60-120 fps eInk exists AFAIK.
Transflective LCDs, which most bike computers use, are also reflective but have better contrast than eink making them more visible in sunlight. They are different than phones.
They obviously do. E-ink display in this topic, for example, is 12:1[1]. The best (contrast wise) e-ink displays available commercially are around 20:1. The trashiest LCD, on the other hand, will be around 500:1.
Measuring the contrast within the display means practically nothing compared to measuring the contrast in the real world environment, which in this case is outdoors and hopefully in the sun.
Compared to the full contrast range of the sun lit real world, all displays emitting light function in a very narrow and very dark contrast range. An eInk display does not emit light, so in that environment you have a clear separation between bright and dark.
> Measuring the contrast within the display means practically nothing compared to measuring the contrast in the real world environment
Even if it had been true, claiming the e-ink has the same or better contrast as LCD is still false. The sun-lit world has higher contrast than any display, yet it does not make e-ink's contrast any good. In fact it makes the low contrast display much worse as you are likely to be looking at much brighter scenes than your bike computer's screen immediately before looking at it and thus having even less ability to distinguish slight brightness variations on the low contrast screen. A transflective TFT display in bike computers also does not emit light, it's still higher contrast in the sun than e-ink.
A paper with printed text on a desk in candlelight is harder to read than any LCD monitor with full brightness emitting its own light. But out in the sunshine, the paper will have hundreds of times better contrast than any LCD. The same is true for eInk.
Frankly, I don't understand why you are arguing, when it is so ridiculously easy for anybody to test for themselves. Just bring your LCD or OLED device out in the sunshine along with your eInk device and see which one you can read from more easily.
TFT displays are really good in the sunshine, but eInk is still a bit better, only beaten by paper for real world contrast.
Has it been a long time since you've used eInk? Maybe they were worse in the past? My oldest eInk device is from 2018, so I wouldn't know about the screens that were before.
>TFT displays are really good in the sunshine, but eInk is still a bit better, only beaten by paper for real world contrast.
You obviously have not done what you are suggesting. Paper is low contrast too, on the level of e-ink.
>Has it been a long time since you've used eInk? Maybe they were worse in the past?
No to both questions. E-ink inherently is low contrast and there is no way to enhance it in this technology: both black and white are done with a pigment, same as print, which caps at ~30:1.
Maybe you live in a place where the sun doesn't shine that strongly? Because otherwise you could do a real life test and know that I'm right in 5 seconds.
I read books on my Kindle outdoors in the blazing sun, and so do most of the millions of people who have Kindles or similar devices. Contrast is excellent. In the same conditions an LCD phone is just a black mirror which you can hardly make out any kind of information form. An OLED is better, and you can see everything on the screen dimly if you strain your eyes. A TFT is even better, but none of them compares to eInk or paper.
So maybe you live in Britain or in Norway, or somewhere similar where it's cloudy all the time? You saying that paper is low contrast baffles me, actually. It seems like you are hung up on the contrast within the device, which is irrelevant for outdoor use, where the only thing which matters is the contrast as part of the real world environment.
Let me ask you, who is the faster runner: The fastest runner on your street or the slowest runner in the Olympics? Because you seem to be arguing for the former because of measuring within limits that do not confirm to the real world - where there is a sun.
I live in Texas. I think you are just confused about meaning of the word "contrast" because you keep using in a way that makes no sense for contrast but makes some sense for brightness. Contrast in this context is the ratio of luminosity between brightest and darkest areas of a display. For a non-emissive display such as e-ink or LCD in a bike computer the ambient light level makes zero difference: the white pigment in e-ink will reflect/diffuse ~15 times more light than the black pigment in the same. Light areas in an LCD screen will reflect 1000 times more light than dark areas. The absolute amount of light above quantum level makes zero difference, it's the same for a candle, Sun or a supernova star - the ratio i.e. contrast remains the same. An e-ink display can be brighter than a reflective LCD though due to higher albedo, this is likely what you are talking about.
Also, if you really try to do what you suggested - you should not use an LCD phone, phones do not have reflective LCD displays but use backlight instead so the contrast on those decreases with increase of the ambient as both light and dark areas reflect the same amount of ambient light and the only difference is the backlight's emissive portion, the higher is the ambient, the lower of the ratio i.e. contrast.
"this is just my preference, but I really prefer to just plop my phone on my handlebars"
It's not a preference. There are a slew of issues around physical damage. Running out of power is far more of a problem than you make it out to be. There are major visibility issues (thankfully Garmin is working on this by continuing their idiotic OLED push /s) and water ingress issues. 1M submersion rating is NOT "driving rain while riding at 15-20mph."
The only people I see with phones on their handlebars are newbies.
eInk is the right display tech. I think this will do really well. It might need a UV filter.
That said, I don't love needing a separate device (hence, I don't own any bike computer). This is just my preference, but I really prefer to just plop my phone on my handlebars. So I'm building a bike computer app for iPhone: https://x.com/mholt6/status/2090529441944687087 (trying to get Apple to approve my developer account / business info, but they're hung up on my website of all things).
Phones are definitely not ideal in terms of display and energy use, but, I have found that with proper optimizations, energy use is a non-issue. To offset display problems, the app has several ride modes: a rich map display with 3D road or satellite view; a high-contrast wireframe map that looks great at both high and low refresh rates because it has no analog-style gauges; an instrument panel dashboard view; and a voice-only mode that has big touch zones for on-demand voice updates, using a state of the art mobile voice synthesis model. For connected radars, the app also renders radar data and has a screen like Tesla/Rivian's autonomy displays.
The app automatically manages thermals by switching modes to preserve battery life.
In my testing so far, by managing energy, making really good voice feedback, and using high-contrast screens (every mode other than the "rich" map), even a dimmed iPhone display is quite a usable bike computer in high-altitude sunlight.
But man, that eInk looks so clean and nice. Definitely the superior display! Nice work and I hope to learn some things from it!
EDIT: Woah, you got ANT+ support using BLE radio? I am not surprised that that is possible, but dang, that must have been a clever LLM.