Started by the Pedalwise team from official manuals, support pages and repair videos

Hex keys (also called hex wrenches or Allen keys) are L-shaped or handled tools that fit the six-sided sockets in most bolts on a bike or scooter. They are the tool you will reach for most often.

What it's used for

Park Tool notes that most of an e-bike is ordinary bicycle hardware, and that a metric hex set handles handlebars, seatposts, saddles, bottle cages and cable work (Park Tool e-bike tools). On disc brakes you will also use hex keys for caliper bolts and some pad retaining pins (Park Tool pad guide).

What to look for

• A metric set, ideally one made for bicycles, as Park Tool suggests (Park Tool).
• Star-shaped (Torx compatible) bits too if your bike uses star fittings, since some e-bikes do (Park Tool).
• Hex keys don't cover everything. Many hub motor axles use nuts that need a box-end metric wrench, typically 15 mm and sometimes 18 or 19 mm (Park Tool). Check your owner's manual for the sizes your model uses.

Using it safely

• Make sure a bolt threads in straight. Park Tool warns that a cross-threaded bolt will not tighten properly (Park Tool torque guide).
• Don't tighten past what the weakest part can take, and use a torque wrench where the maker gives a value (Park Tool). See Torque wrench.
• Seat posts need only enough clamping to stop slipping, so avoid overtightening them (Park Tool).

Guides that use it

• Replace disc brake pads
• Adjust mechanical disc brakes
• Clean and true brake rotors
• Adjust a rear derailleur
• Fix a flat on a rear hub motor wheel

Sources

• What tools do I need for my e-bike, Park Tool
• Torque specifications and concepts, Park Tool
• Disc brake pad removal and installation, Park Tool