Quill stem adapter 22.2 , this part allows you to put a modern threadless stem on older bicycles that use a quill type stem, the size of this quill is 22.2mm (1 inch ), the area the a threadless stem fit on is 28.6 mm (1 1/8 inch ) .
the reason many people convert to this system is that you have many more options in the length and angles of stems available in the threadless style , then existed in the old one piece cast type. another nice thing about the modern threadless types is most have a removable face plate, this allows the stem to be easily changed with out taking parts off your handlebar.
A few notes
1. The clamping area for the stem on the adapter is 40mm, see the photo of the stem for an example of this a stem with approximately 40mm for clamp area will be the best fit .
2. Stems have minimum amount of the quill that needs to be in the fork, this quill needs to be inserted 70mm in to the fork.
3. Always grease the quill when you insert it in to the steertube of the fork.
4. this sale is for just the quill adapter , threadless stems are not included .