Corki Varia Radar and Seatpost Mounts for Garmin Varia RTL510

I needed a way to mount my varia radar to my Trek Speed concept. The seatpost mount Garmin provides does not work as the seat post is too deep for the included o-rings.I was decided to use a K-edge go-pro seat rail mount and Garmin's quarter turn to "friction mount" / GoPro adapter (Part 010-12494-00). Garmin support confirmed this should work. They were incorrect.The Garmin adapter is both 90 degrees rotated from what you need (||| vs =) and the wrong mount "gender". GoPro mounts have three prongs, GoPro cameras have two prongs. All GoPro extensions have three prongs on one end and two on the other. The Garmin adapter has three prongs same as the mount. Finding a 2-prong to 2-prong adapter was difficult. There was one on eBay, but the quality was questionable.So instead I ordered this. The GoPro to Garmin 1/4 turn adapter works perfectly. It's the correct orientation and allows you to change the orientation if needed. It is als the correct end of the GoPro mount, two prongs. I'll see how it holds up, but at first look it is as secure and sturdy as the Garmin parts.I already had the K-edge mount on my bike so I did not use the included seat rail mount. Having said that, this one seems fine. The opening between rails for this mount a bit wider than the K-edge and hence a bit wider than my seatpost clamp. If used you'll need to mount it as shown in the picture, a bit up and towards where the seat rails flare out. Doing this you avoid needing a short GoPro extension as my setup required with the K-edge.I've spent ~$70 on getting the garmin adapter and k-edge mount working. This gets the job done for roughly a third of that. I wish I purchased this first, it would have saved me money and frustration.

Other reviewers have noted that the machining and overall quality on this mount are excellent. They are. It is a solid product. Others have noted, too, that it doesn't work with all saddles. I can understand that too, but the fact that the quarter-turn mounting plate can swivel up or down is important. If you can get the little brackets to fit on your seat rails, you can make the light work. What you can't do is attach this mount to your saddle, then expect to put a rucksack-sized seat pack down there. The attached photo shows the mount with the Varia radar light attached to a Bontrager Nebula saddle, and a Bontrager Elite Small Seat Pack (fully loaded) mounted in front. This setup works well if you are using your seat bag only for "emergency" items, and don't have to access it frequently. That suits me fine, as the mount keeps my $200 taillight secure.

The biggest challenge here is "will it fit YOUR saddle rails?" The metal clamp has two grooves which hold tight to the under-saddle rails. But there is no real adjustment available.Most bicycle saddles have rails that are very narrow at the tip of the saddle, and gradually get farther apart towards the back of the saddle.And once the rails make an upward turn along with the bike saddle, they usually spread apart a lot.For my saddle, which is a standard saddle size common on many road bikes, this clamp would only fit in the 'downward' position. Meaning, it would NOT allow the Garmin radar light to face rearwards; only downwards.So the solution is to get GoPro type extensions to angle the light upwards. I did this, like another reviewer, and it's not ideal. You can see the black extension arm in my photo. Without this extension, the Varia light would be angled down at my rear wheel :(The other negative on this is that the white part you see in the product photo is like a 3D printed plastic piece. It's very hard plastic. It's like the standard GoPro adapter (3 on one side and 2 on the other) When you push it in to the metal adapter for the first time, it is a VERY tight fit, and the metal actually CUTS the white plastic pieces. I was left with plastic shavings on the floor!After a few times of shoving it in, it wasn't so tight, which could be a good thing, depending on your preferences.If they made the clamp fit a wider range of saddle rails, and accounted for the fact that most saddle rails spread apart (are angled) and not perfectly straight, this would be a fantastic product.Also, don't forget you can simply NOT use the Garmin twist lock adapter, which renders this clamp a basic saddle/seat rail GoPro mount that could be used for a camera or something.-----Update after 1 YEAR:I uploaded a photo. On the left is the clamp under my saddle. On the right is the GoPro type adapter (yellowed-white plastic is showing its age and use). The middle is an extension bar I got, which allowed me to angle the Garmin Varia properly. With my saddle, this particular product did not work out of the box with that extension.The plastic 'gopro' type adapter continued to get loose over time. Every large bump would mean it slipped, causing the radar light to angle down at least 20° Not good.My solution was to use spray adhesive on the two halves of the GoPro adapter piece. This has held up now over a few hundred miles. It's not a fully permanent bond, so I could remove it if needed.My immediate family now all have varia lights, so I'll be getting more of these adapters, but I know, going into it, that it is not a one-size-fits-all solution, so depending on my kids' bike saddles, this specific adapter may or may not work. And/or I'll need extension bars to get the light angled level again.If the manufacturer came out with a new version that had multiple rail slots and fit various saddles, it would be perfect. (Oh, and upgraded the plastic used in the GoPro adapter pieces. The plastic is too 'slippery' which means you have to crank down hard on the screw, which strips off some plastic, which means you have to use spray adhesive like I did! :)