I would be more concerned about the rubber bands popping off more than I would be from the twist lock. I solved this by getting a Garmin twist lock adapter that attached to my saddle rails.
https://www.amazon.com/LICHIFIT-Bicycle-Support-Seat-Post-Rearview/dp/B0832D9DMW
I have a ‘D’ type post and had similar issues. I wrapped part of the post with a rubber tape to aid in providing friction for the mount.
I just bought a saddle mount that works much better.
I have something very similar and love it.
LICHIFIT Bicycle Saddle Support Seat-Post Mount Tail Light Holder for Garmin Varia Rearview Radar / RTL510 https://smile.amazon.com/dp/B0832D9DMW/ref=cm_sw_r_cp_api_glt_fabc_4WN0X9M5XWDP9J4VX5MN?_encoding=UTF8&psc=1
The aero mount fit my bike just fine but I now use this because it looks way cleaner https://www.amazon.com/gp/product/B0832D9DMW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
This is the saddle mount I use for my radar. That said I used the rubber band on my specialized venge for years without any problem whatsoever. https://www.amazon.com/gp/product/B0832D9DMW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Mount link: https://www.amazon.com/gp/product/B0832D9DMW/ref=ppx\_yo\_dt\_b\_search\_asin\_title?ie=UTF8&psc=1
Extension (if you use a saddle bag): https://www.amazon.com/gp/product/B01IQPD9DU/ref=ppx\_yo\_dt\_b\_search\_asin\_title?ie=UTF8&psc=1
Pictures: https://imgur.com/a/SB9s8Fk
Mount link: https://www.amazon.com/gp/product/B0832D9DMW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Extension (if you use a saddle bag): https://www.amazon.com/gp/product/B01IQPD9DU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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Pictures: https://imgur.com/a/SB9s8Fk
Saddle Bag: Silca Seat Roll Premio (I believe this model was discontinued for their newer one)
Mount: This amazon mount (https://www.amazon.com/gp/product/B0832D9DMW) with this extender (https://www.amazon.com/gp/product/B01IQPD9DU)
Looks like this: https://imgur.com/a/SB9s8Fk
I have mine mounted to my saddle, maybe this might be of use to you?
Pictures: https://imgur.com/a/SB9s8Fk
Mount link: https://www.amazon.com/gp/product/B0832D9DMW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Extension (if you use a saddle bag): https://www.amazon.com/gp/product/B01IQPD9DU/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Purchased off Amazon
- Tail Light Holder for Garmin Varia Rearview Radar
- Same Direction Straight Joints Mount for GoPro (I bought this to extend it and use my saddle bag)
I've had great luck with this
LICHIFIT Bicycle Saddle Support... https://www.amazon.com/dp/B0832D9DMW?ref=ppx_pop_mob_ap_share
LICHIFIT Bicycle Saddle Support... https://www.amazon.com/dp/B0832D9DMW?ref=ppx_pop_mob_ap_share
Thanks! It's this mount
LICHIFIT Bicycle Saddle Support... https://www.amazon.com/dp/B0832D9DMW?ref=ppx_pop_mob_ap_share
I got one of these to mount to my saddle rails instead: