What wouldn't you be without......

[Ripple]

A bike.

 

[TheDoctor]

My Brompton

 

[All uphill]

Allen keys

 

[alicat]

My mini track pump. So much easier to pump tyres up after a p**cture.

 

[tyred]

Guinness

 

[froze]

It sounds like you mean in terms of safety, I won't ride without a helmet, to me that's huge. In second place comes lights, even during the day in flashing mode because of all the idiots looking at their phones instead of driving and paying attention.