The rear derailleur skips on the third gear when I push hard

Back to list2026-08-16
You

The rear derailleur skips on the third gear when I push hard.

ChatGPT

Cable tension first: a quarter turn on the barrel adjuster while pedalling usually finds it. If it only skips under load and shifts cleanly otherwise, suspect a worn cassette paired with a new chain, which no amount of adjustment fixes.

Tool steps: 3 (reasoning summary, call to python, execution output)
reasoning summary
Checked the query plan, then compared index options.
call to python
rows = run_sql("EXPLAIN (ANALYZE) SELECT ...")
print(rows[:3])
execution output
Seq Scan on events  (cost=0.00..812431.00 rows=41203122 width=16)
  Rows Removed by Filter: 38996878
Planning Time: 0.214 ms
Execution Time: 11842.663 ms
You

What is the most common way people get this wrong?

ChatGPT

Doing it once and never verifying. The setup is the visible part, so it gets attention, and the check that would catch a silent failure never gets written.