wayold

Sorry if this question has been asked before: I'm trying to mount a Garmin Varia radar to the seatpost of my old Domane. At 1.35" diameter the seatpost is a bit too thick to work with the supplied o-ring mount. I was able to make it work by combining two o-rings together as shown. The result was a bit too loose so I padded it out with a spacer made from 6 layers of old inner tube. It feels reasonably firm now, but it does look pretty klujed together. What I'm wondering is whether that sort of cobbled together mount will be reasonably secure or if I'm just asking to lose the radar on the first semi-rough road.

I know I'm re-inventing the wheel here and you guys must have figured out years ago whether this or any other mount works well with thick seatposts like this. So please give me the benefit of your experience.

Polaris OBark

Get this:

wayold

What is the bore diameter of that part? I bought something that looks exactly like that but it has an ID of 31mm = 1.22" and is too small to fit on my seatpost. Even if I try boring it out the distance between the pin on one side and the bolt on the other is almost 1.35" - so close that I think the integrity of the mount would be destroyed if I bored it to that diameter. If versions of this part are made for thicker seatposts then I would be happy to order one.

If not I could fabricate something out of Delrin with a 1.35" hole that clamps to my seatpost and then cut apart the mount you recommended and bolt it to that Delrin piece, but that's a good couple hours work for me (amateur hack machinist). I may yet do that if folks here think my quick and dirty approach is unsound.

Barry2 

If you just want a better oring.
https://www.oringsandmore.com/
I've used these guys in the past.

Barry

surak

KOM Cycling makes a Varia mount that uses a knock-off BOA dial. I bought one because using the silicone band to swap the mount between bikes is a pain. I'm happy with the new mount, although it takes a bit of effort to ratchet it down as tight as I like.

biker128pedal

See if Trek has seat post reflector mount for your Domane. If so you can get a 3D printed Varia Radar mount. This is what I did for my 2021 Domane with its odd D shaped post. I wanted to mount it to the frame and not the seat post. The frame is 1.39 inch dia D shaped. The Garmin mount shown above does not fit. I tried. It may go up to 1.28 inches but does not flex much.

Tourist in MSN

When in doubt, add a small diameter cord as a tether.

Canker

or just go to a hardware store and look through their o-rings

sarhog

This mount is also incompatible with the Canyon/ Ergon split seatpost.

Polaris OBark

It is made by Garmin, and indeed 31 mm without the inserts is probably its maximum. It fit my wife's 31mm seatpost with a little bit of room to spare, so I thought it might be enough, but didn't bother to do the inch/mm conversion. Sorry.

Polaris OBark

Not if you put it below the split.

sarhog

The range is much better with it up as high as practicable on the post. Below the split the tire partially blocks the transmitter and adds false positives.

Polaris OBark

You can get one of those mounts that puts it up on the rails. There is also one that does this in such a way as to permit having a saddle bag as well.

Or you could get a different seat post.

sarhog

Thanks. I just added the comment for others that may be considering the mounting bracket.

Iride01 

I'm not sure why you think your tube is too thick and needed to be padded. All that is needed is for the tube to touch on on two points of the mount. One point on either side of the notch or v in it. No need for it to fit precisely and touch all along the curve of the tube and mount.

And Garmin, when you buy the product new, should have given you all sorts of different sized o-rings to fit many different tube sizes. For my Varia there were two differing mounts, one more fitting for a profiled tube and another for round tubes.

While you can purchase mounts that might look better and hold position better, I just took some electrical tape and wrapped it over the o-rings to keep my Varia pointed in the correct direction.

qnz

I have saddle mounts on all my bikes because the rubber band sometimes is loose or I've knocked the light sideways.
There are a few different companies that make their version of this:
magcad-designs.com/products/magcad-garmin-varia-saddle-mount

wayold

So here's what I eventually came up with. Feel free to critique.

I started with the clamp recommended by Polaris OBark that I'd purchased previously. As mentioned earlier its borehole is too small for my seatpost. However, it does contain a nice bayonet mount for the Varia which is easily removed:





Now I just had to find a way to attach that mount to my bike. So I spent a day messing around with some scrap Delrin in my machine shop and ended up with a clamp sized to my seatpost attached to a receiver that mates to the bayonet piece:




The bayonet fit in there nice and snug:



I then mounted all of that to my seatpost. A few details to note: I made the borehole a few thousands wider than the seatpost and filled the gap with some strips of old innertube so as not to damage the post by directly clamping against hard Delrin. Also note the 17 degree angle machined into the bayonet receiver so that the radar will sit verticallly when mounted to my 73 degree angle seatpost.




Finally with the radar attached everything looks good. I guess the proof is in the riding and I'll find out if it all holds together soon enough.

thin_concrete

That’s really cool - great job! Definitely let us know how it works!

Fentuz

I used one of these on all my bikes