Top all-time · #19771
Robin Grell
Personal blog · grell.dev/blogsecurityprogramming
Robin Grell's personal blog at grell.dev covers security and programming. Since 2025, 3 different Hacker News readers have linked it 10 times, most often “I gave the AI arms and legs then it rejected me”. It is still writing: the last post was on 2025-07-07, and you can follow it by feed.
Too few sampled comments (1) to say how often HN recommends it.?
Why HN links it
Posts by Robin Grell on electronic bicycle components and security, including an attack on Shimano Di2 electronic shifting. The one HN comment quotes the post's claim about attack range and pushes back on it.
Summarised by Claude from a sample of 1 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Open-source developer and security researcher. Linux, GTK, and input simulation.
Most-linked posts?
- /blog/di2_attack2 people · 4 mentions · first linked 2025-07-02
- I gave the AI arms and legs then it rejected me2 people · 3 mentions · first linked 2025-07-07
What Hacker News says?
You can find the writeup of how I downgraded the firmware here: https://grell.dev/blog/di2_downgrade The actual attack is described here: https://grell.dev/blog/di2_attack
Comment linking /blog/di2_attack
on “Ask HN: What Are You Working On? (June 2025)”Submitted I gave the AI arms and legs then it rejected me as a story · 809 points
HN discussionI am the maintainer of a library to simulate keyboard and mouse input. I didn't start the project but took over the maintenance and have since rewritten pretty much all of the code. I recently found out that Anthropic is shipping it in Claude Desktop for some unreleased feature which is probably like "Computer Use". I noticed they had an open position in exactly the team responsible for the implementation and applie…
Comment linking /blog/ai_rejection
on “Ask HN: Have you ever regretted open-sourcing something?”Submitted I gave the AI arms and legs – then it rejected me as a story · 5 points
HN discussion> https://grell.dev/blog/di2_attack > must be within a couple of meters of the bike The range of radio transmitters/transceivers can be increased, and accidental transmissions from various things could affect it. Choosing to allow any kind of remote control over a manned vehicle is a risk. There can be benefits, but winning a race may not be worth giving up your life. Similarly, I don’t want IoT devices and won’t co…
Comment linking /blog/di2_attack
on “Every part on a bicycle is safety critical”Modern bikes allow novel attacks too. I wrote a blog post about how to downgrade the firmware of a Shimano Di2 groupset and doing a replay attack to shift someone elses bike. https://grell.dev/blog/di2_downgrade https://grell.dev/blog/di2_attack
Comment linking /blog/di2_attack
on “Every part on a bicycle is safety critical”Fun read! Now that some bikes have electronic shifting, you can attack the bike itself. I wrote two blog post about how to downgrade the Shimano Di2 shifters and do a replay attack to remotely shift it. You can find them here: https://grell.dev/blog/di2_downgrade https://grell.dev/blog/di2_attack
Comment linking /blog/di2_attack
on “Reverse engineering Lyft Bikes for fun (and profit?)”