I’ve used both. Pro Ones are a pure road tyre, and less robust than the earlier ‘Ones’ but good grip, speed and suppleness. G-One Speed what used to be called S-One is more of a do-anything tyre, so slower, heavier but more robust than the Pro One. Pays yer money, makes yer choice. Depends on what you are riding on. G-One Speed will take rough roads and the odd towpath. Pro One is just road.
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