I only have a saddle-rail mount for track bike, but they are pretty hard, tough nylon, and on the stem-mounts the standoffs are steel. Whether they are ideal or not, I don't know.
Ah, I didn't know they used metal inserts. Makes sense.
@Brommers started
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I only have a saddle-rail mount for track bike, but they are pretty hard, tough nylon, and on the stem-mounts the standoffs are steel. Whether they are ideal or not, I don't know.