Garmin Varia RTL515 installation on Trek Madone SL6

Hi All,

After reading a thread about not so friendly drivers and the additional safety Garmin Varia rear radar provides I have decided to invest in one. The challege with Trek bikes is that everything is geared towards Bontrager accessories and installing Garmin Varia radar with supplied mount options is not an easy task.

One of the options would be to get a seat rail mount with a quarter turn socket and mount it right under the seat, but that negates an option to mount GoPro camera at the same time. After some digging on Garmin forums and googling various options I have found a 3D printed adapter that might do the trick:

radar 2.JPG-640x480

I am willing to give it a try at the same time I would like to hear any opinions or suggestions you might be willing to share.

Thanks in advance,


I just got a 515 and it comes with three different mounts for seatpost ( round, flat and v shaped). I think this is designed so it fits any seatpost / mast.

I would try the stock ones first and then see if you need to do anything else. I think one of the stock ones will work.

I have tried using the stock adapter and pads that came with the radar. The two elastic bands it came with are too short and I had to resort to household elastic bands (not a road ready version, but good enought to check the fit and the looks).

One of the pads fits the rear side of the seat post just fine. At the same time it is far from ideal slick and solid setup. And I am pretty sure that over time it would rub against the paint enough to leave a mark/scratch.

I have seen on Garmin forums that people hack through the adapter and the pad to make a hole and just bolt it to the frame.

I see your issue. I have a saddle mount on another bike that does work well. If you are worried about paint you could put some helicopter tape on it ( the clear stuff you sometimes see on chain stays). Basically invisible and will protect the paint.

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Status update: the 3D printed thingy got delievered today. Of cause, I had to install it right away. The end result looks pretty good. Road test is scheduled for later tonight, subject to weather conditions.

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Looks pretty slick. How sturdy is it?

It fits super tight. I had to use a screw driver as a lever to twist the adapter and mount it to Varia radar first before I could attach the whole thing to the bike. So, now I am thinking that I would need to charge it without taking it off (fortunately the charging port is at the bottom and easily accessible).

And it is not a quater turn, but more like 135 degree turn. And the whole structure is pretty solid.

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Looks good and where can you buy it ?
Can you share the link ?


Hi Sammy,

Sure, here is a link to the website where you can order this 3D-printed part:

Kind regards,

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Thanks Alex !

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Hey Alex,

Bringing this thread back form the dead a bit. I just got a similar mount from shapeways. How has yours held up? Mine is a little rough in places so I’m thinking of sanding it gently. How has the colour lasted? I hear the black can fade. Did you treat yours with anything e.g. wax or sealant?

Hi Oliver,

I have used mine over the summer and it worked great. I keep the Varia radar mounted at all times and just charge it once in a while. And I haven’t really noticed any discoloration or any material degradation.The mount is still pretty sturdy.

Kind regards,


Valve caps -5 :wink:

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As an option and something working very well for me is this under seat mount from Amazon. It is very secure and puts the Varia at the right height. If you are riding with a seat mounted bag (I am not, all my items ride in my jersey pockets…this might not work for you…

Also, this will pretty much fits any bike.