AUPET Water Bottle Bag Carrier,24oz/32oz Insulated Neoprene bottle Sling Holder Case Pouch Cover for 1000ML/750ML Bottles with Shoulder Strap for walking

I would not bother with a drink holder. I have tried several and none of them work well. Even with the front suspension on the G3, any significant road shock will travel right up the stem, into your drink holder, and eject the cup right out the top. Unless you can find one that fastens over the top of a cup to hold it down, you will lose your cup or bottle fairly easily. I now just carry a water bottle sling with me that works much better, e.g. https://www.amazon.com/dp/B012S9FZL4