With this pack the post mount will be too low, so I went to amazon and found the clip mount, but Canondale's tab on the back of the pack is oriented sideways. That's why the pen is inserted, to show the orientation. Most packs seem to have the strap attached so the 'clip' would insert from the top.
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I also saw the mount that attaches to the seat wires, but the pack's attachment straps look like they'll block that as well.
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Any ideas on how I can mount the radar?
Edit to add
Bike Cannondale Topstone 1
Cannondale Medium pack
https://www.cannondale.com/en-us/gear/equipment/bags/saddle-bags/contain-medium-saddle-bag
Garmin Varia RTL515
by NeedzCoffee