How to Harden a Soft Food Delivery Bag - Simple DIY Reinforcement for Bike Couriers

A soft food delivery bag can collapse, shift food during rides, and put stress on zippers and seams. One simple way to improve stability and durability is to add internal structure.

In this video, we show a step-by-step DIY method to reinforce a delivery bag using cardboard. The cardboard frame creates rigid walls, improves food stability, and adds an extra layer of insulation — without buying a new bag.

The process includes measuring the bag interior, cutting and folding cardboard, reinforcing corners, and fitting the finished frame inside the bag. At the end, the upgraded bag is mounted on a bike and taken for a short test ride to show how it behaves in real delivery use.

This is a simple, low-cost upgrade for bike delivery riders who want their existing bag to work better and last longer.

(The bag shown is mounted on a Granny Wheels rear rack expander.)

Chapters:

00:00 Cutting and flattening a cardboard box
00:10 Marking cardboard width to match the delivery bag
00:13 Tracing the cut line with a Japanese knife and steel ruler
00:18 Cutting the cardboard
00:28 Laying out the long cardboard piece for folding
00:31 Measuring the inner length and height of the delivery bag
00:37 Marking folding lines on the cardboard
00:42 Scoring the folding lines (partial cuts)
00:46 Folding the cardboard to form the box
00:54 Gluing the box flap
01:00 Clamping the glued seam
01:03 Reinforcing the walls and corners
01:18 Inserting the cardboard frame into the delivery bag
01:29 Installing a rack expander (Granny Wheels)
01:48 Mounting delivery bag on bike rack (with bungees)
02:00 Test ride

Read the complete guide on our website:
https://grannywheels.com/2025/12/16/h...