Show HN: Open-Source eInk Bike Computer | Hacker News Reader

Show HN: Open-Source eInk Bike Computer

opentrailpaper.com

424 pointsstingrae134 comments

Hey all, i just launched my Eink Bike computer project and think it is cool.

Another tidbit, in the crazy things that AI has done... It has helped create a ANT (common sensor wireless protocol used in workout/biking) implementation for ESP32 by messing around with undocumented registers: https://github.com/RaemondBW/esp32-ant

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The semi-interactive walkthrough on the website is really cool, great way to show the UX.

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

If you mean that you push a 18650 inside the steerer tube and have the display at the cap level - how do you preload the headset then? You need to pull the steerer up somehow and it's done via that cap and a bolt that goes through it into a compression plug/star nut inside the steerer. If you place something under the cap it needs to fit between that bolt and the inside of the steerer tube, which 18650 can't.

Some modern headset designs don't use the top cap to do that. There's a bunch of products that exploit that to put toolkits, spare CO2 canisters or whathave you in that spot.

Sure, threaded headsets (hardly modern, but they do still make bikes with those) don't use top cap, but they also don't have a hole at the top, which products you are talking about?

PS. I searched and found some in-steerer storage. It's not a headset but essentially a hollow compression plug replacement with a top cap moved to the bottom. I have never seen a road fork with a hole at the bottom so it is likely limited to MTB forks and, since there is no compression in that thing, it might be not very safe with a carbon steerer.

Frame storage is my dream feature for a road bike. You see it on gravel bikes and it makes me very jealous.

I ride several bikes so I would not know what to use the in-frame storage for. I want the things like repair kit (with batteries) and lights (also with batteries) to be movable between bikes so the batteries are charged in time. Even if all my bikes had in-frame storage it would be a chore to move its contents.

Some newer road bikes have it too. Canyon Endurace and Trek Domane, for example

Trek dropped that (and "suspension" whatever it was called) from the new Domane.

After you clamped the stem, the preload job of the cap is done and it can be replaced.

Mm. Yes, but I wouldn't trust that.

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.

"Exposure to vibrations, like those generated by high-powered motorcycle engines, might impact iPhone cameras" https://support.apple.com/en-ca/102175

I attribute my iPhone 7's camera failing with mounting it on my bike.

> camera failing with mounting it on my bike.

I’ve wondered about this. Does it shake a lot less when it’s in a pocket for the same ride?

Presumably yes, as every cyclist ever does that.

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.

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.

> eInk is the right display tech.

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).

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?

Good luck!

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.

Alas, no X account but I'll set a remind to check in again in a month or two. Cheers.

For many, a separate device is a feature. Not using the phone battery and not poosibly damage my phone (fall) is good.

> eInk is the right display tech.

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.

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.

Trying to outbright the sun on a battery-powered device is an approach I've always found questionable.

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.

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 don't have better contrasts. They have blacker blacks, but eInk has much whiter whites.

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.

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

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.

> Contrast in this context is the ratio of luminosity between brightest and darkest areas of a display.

That is the internal contrast of a screen or printed material. I agree, and that type of contrast is important if the screen emits its own light.

However, for outdoors use the only contrast that matters is relation to the real world, aka physical reality. And brightness of course becomes the main factor.

Also, thanks for pointing out you are talking exclusively about transflective/reflective LCD. It seemed to me for a while you were talking about any type of LCD. But even so, eInk and paper has better contrast in real life outdoors use, because we have to measure contrast in the human eye and not within the device.

The human eye adopts to the brightness in the environment and makes a contrast "scale" according to this. The nearer your screen's black color is to the black of the human eye's black in that situation, the better. And the nearer your screen's white color is to the human eye's white, the better.

If either your black or your white is too far from the human eye's calibration, then your screen is no good to use, no matter how good the internal contrast of it is.

There is no limit to how bright things can be or how dark things can be. So the internal contrast between a very deep pitch black and a very dark gray can be 1:10.000, but within a real world sunlit environment it all just looks like black. And this matters, because direct sunlight is 30.000 - 100.000 lux, while an office is maybe 500 lux.

>However, for outdoors use the only contrast that matters is relation to the real world, aka physical reality.

For you perhaps. I, for one, use screens to get information encoded in symbols and graphs, if all these symbols and graphs had no contrast with background I would not be able to distinguish them from the background. You seem to only care to compare the screen's brightness to the real world, perhaps losing your screen and then finding it in the real world, aka reality, is the main usage mode for you?

> But even so, eInk and paper has better contrast in real life outdoors use

You need to give a citation for this which would be pretty hard since we are already discussing a 12:1 device as shown by the spec sheet I've posted earlier. Or are you using "contrast" do describe brightness? In this case I agree - eInk's "black" is just a darker shade of gray so it reflects more light i.e. contributes to higher albedo. It's not great when you are trying to read from that screen but if you are just looking for the lost screen in the wilderness it won't hurt I guess.

You seem to be unfamiliar with bike computers but appear to be using your imagination instead of looking it up so I will state for the record - bike computers are affixed to bikes, a rider checks the computer during the ride and it's always in the same position, bike computers are not thrown into the wilderness to be searched for afterwards so locating one in the real world is rarely a problem facing a bike computer user. If one is detached in a crash, they always have radio and often speakers for more reliable mode of finding than the light reflected from the screen.

This thread was highly entertaining. Thank you two for arguing the topic and special thanks goes out to pandanman for his patience and composure. I guess I just found my next rabbit hole to investigate.

Because most people cycle outdoors and when the sun shines, and eInk is much better than any other display type in bright environments.

LCD screen are pitch black by default. Eink can be white without extra energy

Yes, and there are many other tradeoffs. How do the tradeoffs fit this use case?

"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.

My phone is the root of trust of my life. I would never put on in my handlebars where it can be easily snatched while unlocked, or broken.

Do you hold it in your hand in public? Far more risk of it being easily snatched while unlocked.

Nope. You gotta be careful. I had my Pixel snatched out of my hand in Cambodia. I no longer wave it around in public.

Within 10 seconds I was convinced I needed to try this.

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.

Perhaps Endurain? https://codeberg.org/endurain-project/endurain

intervals.icu?

Looks good, but unless I'm severely mistaken it's a SAAS, not self hosted. As long as it's on someone else's service I don't own it and it's not under my control.

I openly admit, I have not spent much time researching this subject, was just in the back of my brain as I migrate away from SAAS and IAAS.

Wow, amazing work.

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.

I've found e-ink displays super fragile for this use case. They break from a little fall, or even from the constant shaking.

For all their readability benefits under direct sunlight, prolonged exposure also damages or kills them. You need at least a UV blocker for outdoor use, but the heat cannot be avoided.

This is great. One suggestion I have (for these types of projects in general) is to include a BoM and price estimates. Make those front and center. Even though prices shift they give people ballpark estimates for deciding "do I want to spend time on this" or not. It also shows a log of clearly supported hardware and even makes it easier to track tweaks for different hardware as people contribute to your projects.

Very cool! Did you consider Protomaps for the map tile format at all? It's a pretty clever way of storing everything in a single file and their tooling is pretty nice.

I hadnt heard of it. I will check it out.

PMTiles is the underlying technology I believe. We use it on oceanconnect.ca and in my opinion it’s pretty awesome. Very efficient to store and retrieve, and cut our S3 PUT request costs by something like 90% across the project.

Wow. You managed to receive ANT+ via BLE hardware?! I didn't know these two protocols were so similar.

yes. they luckily the same phy, 1 Mbit/s GFSK modulation.

The protocols aren’t the same by the physical link is. Same with 802.15.4 aka thread aka zigbee.

Hey this looks neat, I’ve been thinking on trying something similar. I’ve not encountered the ANT protocol, what bike ya using? Is it a higher level thing that your display is giving you, or something your controller uses? I know Bafang uses CAN protocols in their newer e-bike systems and a lot of manufacturers (especially Chinese) use a proprietary UART protocol to stitch things together on the cheaper end.

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

ANT+ is basically dead because of an EU legal requirement to ensure that personal information is encrypted. So no new devices will be supporting it, and everything has to move to BLE.

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.

what is insane, is that ble is largely unsecured in modern implementations. when testing, i kept picking up everyones whoops/assorted ble devices spamming out heart rate data to whomever wanted to connect.

You don't need AI to decode these protocols. People have already done that. If you look a bit further than asking you favourite LLM for obvious answers there is plenty of OS code available for the LS, KT and Bafang uart protocols. Still recommend you avoid them, they are pretty poor and CAN is way more reliable.

Ant+ is for connecting sensors and other stuff. Like heart rate monitor, power meter, control resistance on a trainer etc.

ant+ is a garmin protocol that is very common with fitness gadgets and in the bike world. It's a bit like bluetooth, but lower energy usage.

It also got nuked from orbit by European regulators. The ecosystem has a huge installed base but no future.

Isn't it only using standard ble hardware anyway? So what's the problem?

They are both using the same physical layer, but the ANT+ protocol scheme is more amenable to ultra-low-power implementations than BLE is. The European belief that my wheel rotation sensor needs privacy through encryption has effectively outlawed the low-power attributes of ANT+ for future hardware.

I think it’s more about the ANT+ sport heart monitors.

This would be a pair great with Gadgetbridge and Endurain.

https://gadgetbridge.org/

https://endurain.com/

Very cool! I made something similar recently with my Xteink X4 ereader - difference being it served as a UI for sensors connected to my phone. Getting the ESP32 to communicate directly to ANT sensors is pretty wild!

Do you have any resources for playing around with the Xteink outside of just reading? I got mine this week and would love to push its utility!

Would love to see video of the application in action. Was recently researching eink displays for motorcycle navigation, but the refresh rates were not up to par for realtime automotive navigation..

i have been using it in my car during commutes for testing. modern eink displays can do pretty high refresh rates. i think i can hit 20hz.

Battery of my Cubot King Kong Mini is slowly dying. I use it with OpenTracks to record my commutes and use as bikecomputer and sometimes Osmand+ for offline navigation. I am searching for alternative, which needs to be waterproof and cheap (my commutes luckily includes downhill trails sometimes - I dont want to break expensive device). The title gave me high hopes, but I suppose I need to keep searching.

Very cool. I was messing around vibe-coding an HR monitor on a LilyGo T5.

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.

This exchange is fantastic! I was immediately impressed, and I'm eager to try it out with my bicycle.

awesome stuff. I have a Wahoo bike comp but would love to use an OSS alternative

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.

I also have a wahoo. Pretty great. Especially its week of batterylife

Love the project and progress made, along with the ESP32 ANT!

But to be more involved and support a project like this I really would need it to be based on a board with proper weather resistance! Hope you find that as an option in the future.

I can't imagine using this in the Netherlands with random rain. The tradeoffs are hard to accept, wondering how it looks and performs in various weather conditions, and if a physical buttoned shell is worth it...

My experience with touch is it works ok as long as you do some arbitrage. I've implemented four touch quadrants on my display and it works good enough in the rain (quadrants are linked to play/pause/next etc for music) that it doesn't do anything I don't want it to do. Only downside is sometimes it misses a hit in the rain.

Weather sealing is quite doable if you accept you need a boatload of glue and you coat your 3d printed case with proper car lacquer or at least a thick coat of acryl. Use reinforced filament, and at least something 70c+ resistant (so no ordinary PLA).

I've driven it plenty in the rain in NL (not this display, my own).

Garmin Edge 10X0 series is touch only (except for pause and lap button). Was a bit apprehensive myself moving to 1040 from my old 5X0 series with buttons only, but no issues in weather so far. More reliable than a phone display with droplets.

I gave up on bike computers years ago after a couple of tries to find one that would survive New England winter. Then I realized I didn't really need to give a crap about anything a bike computer was telling me.

Does this work well in direct sunlight? I know a lot of e-paper panels struggle to refresh in strong sunlight. The waveshare panels look very faded if they update while exposed to UV.

i have ridden with this unit over five hundred miles and not had any issues. though SF Bay Area summers arent as tough as other places.

Maybe they get air cooled if you pedal fast enough?

Cool project. Not sure I'd use it, as my iPhone works quite well for this purpose. iPhones have had always on display since the 14 Pro and 17, and they've had good water resistance since forever. No problem reading it under any conditions.

  - iPhone 15 Pro with quadlock case 
  - various Quadlock mounts 
  - Quadlock mag charging mount with a USB C battery in the top tube bag for long rides
  - Apple Watch (paired to SRAM Powermeter on bike)
  - Record rides using Apple Fitness on Apple Watch
  - Apple fitness syncs to Strava and other services
  - Ride With GPS, Apple Maps, or Google Maps for turn-by-turn (when necessary)

be careful how you mount it, make sure that there is enough dampening. people have had issues with excessive vibration and damaging the OIS and focusing motors in the cameras.

Thanks, hasn't been a problem for me.

~15,000km with this phone. Tens of thousands more on older phones all the way back to the 5s. Which of course wasn't nearly as good: no always-on display and had to use the Quad Lock "poncho" in the rain.

My road bike handlebars killed my iphone camera fwiw. Into the saddlebag it goes now.

Quadlock makes a special dampening mount for this reason.

This is cool, but I bet it will be a grind trying to get to Garmin levels of battery life. They just have it nailed, and an Edge 550 that's ¼ this size can run for over a day, despite its emissive display, and they don't seem to suffer from display scaling since the larger Edge 1050 runs for even longer. That is to say that the larger battery in a larger device more than compensates for the higher display power requirement.

Anyway one thing I think would be nice is if the GPS radio can become a peripheral. Then with that architecture could the head unit just get GPS from your phone?

Only a day? COROS has it beat by having 100+ hours of GPS riding.

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.

> Only a day? COROS has it beat by having 100+ hours of GPS riding.

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.

> and they don't seem to suffer from display scaling since the larger Edge 1050 runs for even longer

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)

Yes, that's my point. You might imagine an advantage for eink if you can make the display as big as you want without blowing out the power budget, but in practice it already doesn't matter.

For some use cases, reliance on a phone is sub-optimal. Multi-day wilderness bikepacking, ultra distance racing, etc -- phones just use too much power when you can't get a few hours of charging every day or two.

Wow, this looks amazing!

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

yes me too. i may be working on something...

Wow, this is really cool. I really needed something for my neo retro build, this might just fit the bill.

Great project. I'm tired of all the brands that stops updates ect.

Do you have a mounting system already ?

Insane! Quality on the ANT too!

There’s no mention of the wheel sensor. How does it get the bike telemetry?

Since the ANT+ protocol implementation seems to already be there, it seems a likely/sensible future path is to implement wheel sensor support. It provides much higher accuracy of speed/distance than GPS and lower power draw.

On that note, this is a world I've recently taken a dive in to. I was about to roll a Pi Zero / ESP data logger to track distance travelled on my commuter bike for planning service intervals. Was keen on a solution that didn't involve draining a phone battery and remembering to start trips, a full bike computer, or smartwatch. After a bit of research I picked up a Garmin Speed Sensor 2 - highly recommend as a bit of stupidly effective tech.

The device straps around your hub and is essentially a coin battery and mems rotation sensor. In addition to running as an ANT+ peripheral it will operate standalone and log the last 300 hours of ride time then sync next time you open the app. Speed and distance is then inferred based on wheel circumference.

I really appreciate this info. I went old school when I hacked my own esp32 bikeputer together with a wheel magnet and reed switch. It was fun to put together, but pretty janky with wires tapped up and it wouldn’t survive any off-roading.

I wasn’t aware of the more modern ANT+ approach. Looking forward to a V2.

GPS

Why eInk? The display updates often, that's a perfect choice for Sharp MIP displays. Also: Please use a fixed-width font for numbers. Seeing the values wobble around looks like a generic website, not like a serious product.

I love this. How do you house & secure your lily on your bike?

Any open source GPS locator for bikes?

Cheap chinese tracker, prepaid sim and traccar instance? That's what mine has.

Wow that's nice ! I especially like that you clearly explain the tradeoffs.

One surprised me though:

> No pressure sensor. There’s no barometric altimeter, so climbing is derived from elevation baked into the map tiles rather than measured — total ascent is an estimate.

The gps from the device do not provide the altitude or is it not precise enough ?

Damn, this looks cool

Funny, I just got done researching the Coros Dura, another eInk bike computer.

technically i dont think the coros uses an eink display. but it is definitely one of the cooler bike computers.

great!

Excellent job! I had no idea about the LilyGo platform. Amazing. I was just in the market for a Garmin cycle computer and I will absolutely give this a go. Thanks!

I love my eInk displays, I love my bike head unit.

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

Anyway, as long as you have fun doing this and some people enjoy it also, congrats!

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

Apparently current GPS screens are compatible with your eyes and the viewing conditions you find yourself in. Congrats! May your eyes never darken and your trails be easy!

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

This device has a backlight enabled by a physical button, and navi refresh rate doesn't matter because you're riding and not staring at it. 1Hz is fine for a reference.

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.

I don't see where I expressed any kind of hate towards the device.

Refresh rate does kind of matter. 1Hz imposes an average 0.5s latency on any update, which would be obnoxious in some situations.

Quite normal on most bike computers already with a slow refresh, even if they're able to refresh faster. You can't really read a number if it keeps changing all the time.

> 0.5s latency on any update, which would be obnoxious in some situations.

What situation?

i can push it as high as 20Hz.

For me, it matters only when I'm futzing with the map: dragging around or zooming. For the rest of the info on the display, anything more than 500ms interval seems like a waste of power.

You’re responding really inappropriately to someone participating productively in a discussion.

IMO at least a better one to do would be a transflective LCD like the original pebble watches used.

I already have a transreflective screen on my current mass-produced bike computer. I don’t see a need to make another one, whereas I’ve never seen an eInk one; I think that’s genuinely cool and the main innovation here.

Heh, I just got a waveshare RLCD to play with sunlight visible higher refresh rate, but then I compared it side by side with the exact e-paper display for this project and I felt buyer’s remorse; the contrast is soooo much worse on the LCD.

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

That’s what most bike gps screens are now.

refresh rate is sort of a non issue. i can push the refresh rate to up to 20Hz, it is largely unnecessary for this project.

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)

I find colour useful for a navigation map, mostly. I think the 4-colour eInk displays would be plenty for that, although they have refresh constraints iirc.

A good UI design would mostly avoid the need for colour.

I agree. But this could be a fun and cheap project to do with kids for their bikes :)

Well said. I don't understand who this would be for.

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