Pro tip: a bent chain at 7:15am on 8th Street taught me to always pack a quick link
I was halfway to work on 8th Street last Tuesday when my chain snapped, and I stood there on the curb for 20 minutes trying to fish the broken ends out of the derailleur with cold fingers. A guy passing by on a hybrid handed me a spare quick link from his saddlebag and I was rolling again in 5 minutes, which got me thinking I should never leave the house without one. What small spare part has saved your morning commute?