What does a bike alarm need?

Alert people in the surroundings

Act as a layer of deterent

There could be a light that would light up

Lock

Make loud noises

Needs to fit a range of bikes

Buzzers / Sirens

Sensors

LED

Lightbulb

Different colours

Key

Could fit on the bike frame

Could fit on the bike handle

Could fit on the bike seat

Automaticbell

Strong locking mechanism

Could lock wheels in place

GPS tracker

Some sort of password

Combination lock