I've always wanted to use a round display and an 18650 to plop a mini bike computer into my headset (replacing the cap). There was a Kickstarter years ago for a project doing that, but it seems to have fizzled out

For me, the next step for this is taking all the sensor data recorded for a ride, and loading it into my own fitness tracking database that I own, control, and isn't tied to someone else's profits.

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.

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.

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.

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?

Good luck!

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.

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.

It's interesting and I clicked on the OP, but why? The variable ambient light conditions, refresh rate, etc would seem to favor standard LCD/etc.

Battery capacity isn't much of an issue for a small screen, and weight carried by the bicycle.

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.

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.

E-ink, instead just lets the sun reflect off of it, does want some sort of light in the dark, but, perfectly visible in full-bright/direct sunlight.

1. https://www.panelook.com/ED047TC1_E_Ink_4.7_EPD_parameter_25...

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.

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.

But I don't see how they both fit together honestly.

  The pros of eInk:
  - low energy usage -> don't matter, current GPS units have +30 hours of battery life already
  - low eye strain -> don't matter, you don't look at the screen for hours at a time
  - visibility -> don't matter, current GPS units adapt to ambient light
  - angle visibility -> don't matter, the screen is right in front of you

  The cons of eInk:
  - refresh rate -> yeah, I don't want the map display to be laggy
  - visibility in the dark -> tunnels, tree cover... I don't want to my GPS to be invisible
  - lack of color -> colors provide lots of information on the map display

  >don't matter... don't matter... don't matter...

For others, some of those advantages do matter. Different strokes for different folks! Cheers mate.

Not sure why needing less battery or having better at-a-glance visibility would be such a bad thing.

One need not love a device, that's ok. But digging to invent a reason to hate it also doesn't seem necessary.

  > But digging to invent a reason to hate it also doesn't seem necessary.

What situation?

it has a nice backlight (basically identical to a kindle display)

color is fair, but i dont miss it.

i do absolutely love how readable it is in direct sunlight (when im mostly riding)

Maybe it would have fared better if I was out in sunlight viewing them, but seeing this thing in person sold me on e-paper for this use case

My use case is a bit more basic than most. I am nearly always on routes I know and just want a few basic stats, but…

I require a bike radar to work. I use a Varia. I like the beep, and need the indication for a car behind. Is there any compatibility with this?

If this question is already answered somewhere, apologies.

The mess of different implementations makes it really hard to hack on and share this kinda stuff.

AI does make it really easy to figure out these protocols now so that’s nice I guess. I just flipped my bike upside down and hooked up a logic analyzer and it took LLM no time to figure it out… it is really impressive

It was quite a rich ecosystem of sensor devices, especially for cycling, including speed and cadence sensors, heart rate monitors, power meters, lights, radar, etc.

It has been extremely popular over the last 20 years.

My thought was I'd love to set an HR zone and then connect it to my e-MTB and have it change power to keep me in a zone.

The refresh rate on my device was horrible, and the models (this was a few months ago) struggled to create a historical line plot of my HR.

I hope we can get a better suited hardware though. Larger buttons, smaller device overall. 4.7" sounds huge, almost size of a phone.

the dealbreaker for me is whether it could eventually work with the Garmin Vario radar (which the Wahoo supports with a nice visualization) -- that is _literally_ a life saver and I no longer ride without it.

And I think GPS is the key power consumption part here. Have you tried opening one of those background location tracking apps that would require your phone to receive GPS all day long? That significantly reduces battery life on your phone. You really want your entire GPS stack running on a power-sipping processor, not on your phone’s application processor.

If my memory is correct, at the price of only be able to sync your rides and routes using a proprietary app that probably also send all your data to mothership.

Why would they suffer from display scaling? At the same device thickness, larger devices have the same volume per cm² of display. And it gets better:

- if they need the same volume for electronics (likely mostly true; you may want a slightly faster CPU and more memory, but don’t need a larger GPS, second WiFi chip, etc), that means more battery volume per cm² of display.

- at small sizes, I guess/expect wall thickness of the case to scale slower than the dimensions of the case, giving larger cases relatively more internal room.

(Googling, I see the 550 is even slightly thicker than the 1050; 16,8mm vs 16,3mm)