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Pinch Bolt
When a round part is held inside another round part, but adjustability is desired, the outer part will often have a slot or gap. This gap will be bridged by a bolt that can squeeze or "pinch" the outer part so that it will clamp onto the inner part. Such a bolt is called a pinch bolt. Most bicycles use pinch bolts to secure the seatpost into the seat tube of the frame, and to secure the handlebars to the stem. Threadless stems usually use pinch bolts to secure the stem to the steerer. Many tandems use pinch bolts to secure their eccentric bottom brackets.
The bolt may fit through "ears" that are attached to the outside of the outer part, or it may close the gap of a split collar which surrounds the upper part of the seat tube.
A few older bicycles used a collar and pinch bolt to secure a handlebar stem inside of the steerer. This system is particularly common on folding bicycles to allow the use of a quick-release for the handlebar stem. This system required a compression slot to be cut into the steerer, and the slot could constitute a stress riser.
