A bicycle is made of many parts, and bolts help to hold the parts together. However, all bolts are not all the same, and they can differ in size and type.
When a bolt becomes loose, a hex wrench or a Torx wrench should come in handy to tighten the bolt. You rarely need to replace a bolt unless it falls off or wears off due to frequent adjustments, especially with the wrong tools.
Below are a few types of bolts on your bike, their location, purpose, and the right tool used to tighten them.
1. Brake Bolt
This bolt is found above the wheels on the rear brake bridge and top of the front fork. It is used to attach the braking system to the front fork and braking bridge and can be tightened by a 5mm hex or tox wrench.
2. Faceplate Hex Bolt
Located at the front faceplate, this bolt is used to secure the handlebar to the stem. It is tightened by a hex wrench 4 or 5 mm.
3. Top Cap Adjusting Bolt
This bolt is located on top of the stem. It aids in holding the headset connecting the fork to the frame. For this bolt, you will need a hex wrench tool.
4. Seat Binder Bolts
These types of bolts are found on the clamp above the seat top tube. They are used to secure the Seatpost and adjust the height. It can be tightened with a 4, 5, or 6mm hex wrench.
There are more bolts holding a bike together, and you can learn more about them with a little online search.