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
Show HN: Open-Source eInk Bike Computer (opentrailpaper.com)
260 pointsby stingrae12 hours ago90 comments
Hey all, i just launched my Eink Bike computer project and think it is cool.
rjrjrjrj an hour ago
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)stingrae 36 minutes ago
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.
rjrjrjrj 26 minutes ago
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.
Rebelgecko 10 hours ago
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
pandaman 3 hours ago
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.
ehnto 2 hours ago
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.
pandaman 2 hours ago
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.
neoCrimeLabs 10 hours ago
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.
dongking 2 hours ago
This exchange is fantastic! I was immediately impressed, and I'm eager to try it out with my bicycle.
mholt 11 hours ago
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.
robot_jesus 10 hours ago
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!
mholt 9 hours ago
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.
matsemann 7 hours ago
For many, a separate device is a feature. Not using the phone battery and not poosibly damage my phone (fall) is good.
mmooss 10 hours ago
> 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.
mholt 9 hours ago
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.
WillAdams 8 hours ago
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.
ianburrell 7 hours ago
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.
carlosjobim 5 hours ago
They don't have better contrasts. They have blacker blacks, but eInk has much whiter whites.
pandaman 3 hours ago
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...
carlosjobim 2 hours ago
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.
pandaman 2 hours ago
> 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.
Gualdrapo 9 hours ago
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.
usern20260720 8 hours ago
LCD screen are pitch black by default. Eink can be white without extra energy
mmooss 6 hours ago
Yes, and there are many other tradeoffs. How do the tradeoffs fit this use case?
carlosjobim 5 hours ago
Because most people cycle outdoors and when the sun shines, and eInk is much better than any other display type in bright environments.
opello 7 hours ago
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.
stingrae 5 hours ago
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.
alabut 4 hours ago
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.
wiether 10 hours ago
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
30minAdayHN 10 hours ago
I agree. But this could be a fun and cheap project to do with kids for their bikes :)
flutas 10 hours ago
IMO at least a better one to do would be a transflective LCD like the original pebble watches used.
kccqzy 9 hours ago
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.
scottbez1 9 hours ago
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
Gigachad 8 hours ago
That’s what most bike gps screens are now.
mattlutze 10 hours ago
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.
wiether 10 hours ago
> But digging to invent a reason to hate it also doesn't seem necessary.
loeg 9 hours ago
Refresh rate does kind of matter. 1Hz imposes an average 0.5s latency on any update, which would be obnoxious in some situations.
matsemann 7 hours ago
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.
lostlogin 6 hours ago
> 0.5s latency on any update, which would be obnoxious in some situations.
What situation?
stingrae 5 hours ago
i can push it as high as 20Hz.
itsdesmond 6 hours ago
You’re responding really inappropriately to someone participating productively in a discussion.
schiffern 9 hours ago
>don't matter... don't matter... don't matter...
For others, some of those advantages do matter. Different strokes for different folks! Cheers mate.
jms703 8 hours ago
Well said. I don't understand who this would be for.
stingrae 5 hours ago
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)
kccqzy 11 hours ago
Wow. You managed to receive ANT+ via BLE hardware?! I didn't know these two protocols were so similar.
stingrae 11 hours ago
yes. they luckily the same phy, 1 Mbit/s GFSK modulation.
tuchsen 11 hours ago
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
monknomo 11 hours ago
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.
jeffbee 10 hours ago
It also got nuked from orbit by European regulators. The ecosystem has a huge installed base but no future.
Brian_K_White 4 hours ago
Isn't it only using standard ble hardware anyway? So what's the problem?
jeffbee 3 hours ago
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.
matsemann 10 hours ago
Ant+ is for connecting sensors and other stuff. Like heart rate monitor, power meter, control resistance on a trainer etc.
__d 10 hours ago
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.
stingrae 5 hours ago
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.
lostlogin 6 hours ago
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.
nickmcc 10 hours ago
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!
financetechbro 10 hours ago
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!
seemaze 10 hours ago
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..
stingrae 9 hours ago
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.
pilina 11 hours ago
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.
__mharrison__ 10 hours ago
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.
shrinks99 9 hours ago
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.
stingrae 9 hours ago
I hadnt heard of it. I will check it out.
steve_adams_86 3 hours ago
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.
evrimoztamur 11 hours ago
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...
matsemann 10 hours ago
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.
Finnucane 10 hours ago
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.
StrLght 9 hours ago
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.
stingrae 9 hours ago
yes me too. i may be working on something...
dinan 11 hours ago
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.
stingrae 11 hours ago
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.
carlosjobim 5 hours ago
Maybe they get air cooled if you pedal fast enough?
hi_hi 7 hours ago
There’s no mention of the wheel sensor. How does it get the bike telemetry?
dchest 7 hours ago
GPS
dumbmachine 11 hours ago
Wow, this is really cool.
I really needed something for my neo retro build, this might just fit the bill.
maxrev17 11 hours ago
Insane! Quality on the ANT too!
zsoltkacsandi 11 hours ago
I've found e-ink displays super fragile for this use case. They break from a little fall, or even from the constant shaking.
orbital-decay 10 hours ago
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.
memoryfault 11 hours ago
I love this. How do you house & secure your lily on your bike?
Lucasoato 11 hours ago
Any open source GPS locator for bikes?
bruce_wayne_ 9 hours ago
Damn, this looks cool
insane_dreamer 7 hours ago
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.