1. Rear frame: Many road bikes and mountain bikes have rear frames, which can be used to place backpacks, bags and other items. If your car doesn't have a rear frame, consider installing one, or fixing the bag on the rear wheel with a belt.

2. Handlebar: You can use the strap on the handlebar to fix the bag on the handlebar. The disadvantage of this method is that if the bag is too big or too heavy, it may affect your riding and handling.

3. Backpack: If you only need to carry some light items, such as mobile phones, wallets, keys, etc. Small backpack can be considered. This kind of backpack can usually be easily fixed on your back or waist without affecting your riding and control.

4. Pockets: If your cycling route is relatively fixed, consider adding some pockets to your clothes to hold things. For example, adding a pocket at the back of cycling pants can easily carry mobile phones, wallets and other items.

It should be noted that no matter which way you choose to place the bag, make sure that the weight and position of the bag will not affect your riding and handling. In addition, in the process of riding, attention should be paid to maintaining balance and stability to avoid affecting safety due to the movement of the bag.