Rear radar

TomZ

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Pacific Northwest
Here's something I came up with to detect vehicles approaching from behind and overtaking. It's a rear radar unit called a Varia 315 that Garmin sells for bicycles. What this device does is detect vehicles approaching from as far back as 140 meters (about 450 feet). Although not intended for motorcycles, it is easily adapted as described below. For readout, I used an old cell phone and the free Varia app from Garmin. The app connects the phone and radar unit via Bluetooth. It displays multiple vehicles approaching from behind and indicates closing speeds by color changes. It generally does not show vehicles if they are traveling slower than the motorcycle, but it does show them as they pass through the blind spot or stop in an adjacent lane. I find that I use it much like the rear view mirror in a car by glancing at the phone display in front of me rather than having to look in the side mirrors. Also, it warns visually if a vehicle is up coming fast when I'm stopped.

For mounting, the bicycle seatpost mount that Garmin provides with it is easily taken apart to yield a small mounting puck that can be attached to a top case. One of the attached photos shows the mounted unit. It's unobtrusive: Most people would not even notice it or know what it's for. The unit attaches to the mounting puck with a twist lock (insert and twist 90 degrees to lock). To avoid having it come loose or be removed by prying hands, I mounted it in the topcase with a thumbscrew (see photo) that locks the unit in place but can be easily backed out to allow removal for recharging etc.

This is very much an experiment and strictly for my own use. I would like to have an audio alert of fast-approaching vehicles to my helmet communicator, but have not yet been able to do that. Also, I'm still thinking about where to best mount the phone, and about extending an unswitched USB charger to the topcase. What I can report is that the radar unit serves the intended purpose very well and gives me added safety when riding.
 

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Checkswrecks

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Thanks TomZ. I see that Triumph now has something like this built into the new Tiger 1200.

A bicycle friend talked about this and there are a number of ways to display alerts. The radar unit is $149 and Garmin has a couple of displays you can mount on the handlebars, or you can download their phone app, or third party GPS displays can integrate it.

One is this $99 head unit:
 

TomZ

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Pacific Northwest
Interesting. Any shots what is displayed on the phone?


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The display only indicates vehicles when they are approaching, so no photos taken when the bike is moving or in traffic.
The app display is very simple: Just two parallel lines indicating the road, car icons appearing at the bottom as vehicles are 1st detected and advancing to the top where the rider "is". A color band at the top of the display changes from green when no vehicle is approaching to amber as the approach is detected and red for high approach speed. The display indicates multiple vehicles but does not show which side they are on in multilane situations. The main thing is to realize that the vehicles are coming up behind you and then check the mirrors. I found the color alert especially useful to warn of fast-approaching cars when stopped at a traffic signal.
 

TomZ

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Thanks TomZ. I see that Triumph now has something like this built into the new Tiger 1200.

A bicycle friend talked about this and there are a number of ways to display alerts. The radar unit is $149 and Garmin has a couple of displays you can mount on the handlebars, or you can download their phone app, or third party GPS displays can integrate it.

One is this $99 head unit:
A couple of comments on this. As you said, there are other display options, including a watch. I considered the $99 head unit , but did not want to put much money in this. The Varia 315 was on sale before Thanksgiving for $99 with free shipping and the old phone was essentially free, so I'm only a little over 100 bucks into this including sales tax and the thumbscrew. As far as I know, the Varia integrates with some GPS units for bicycles, but not the ones for motorcycles, even Garmin Zumos. I could hope Garmin would take note and eventually adapt their rear radar to work with their GPS units and especially with Bluetooth helmet communicators. To my knowledge (I did not know about the Tiger 1200) there is no other product like this on the market.
 

blitz11

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I bicycle commute from August until May in Bozeman, MT. (I only work summers now.) previously, i've bicycle commuted year round for ~35 years in Minneapolis and in Iowa.

The problem with this is WTF are you gonna do on bike if you're gonna be hit from the rear? You can't accelerate, which leaves run off the road IF there's not a curb. Neither is a good option.

Beyond that, how do you accurately measure the trajectory of the vehicle approaching and estimate that it's going to collide with you? (I worked on ADAS/Autonomous vehicles for 25 years before moving here, so i know how lidar/radar work and perform.)

Cars pass me with 2' of clearance (often less) all the time. How is radar and the integrated signal processing going reliably estimate a crash?

Of all thing things I've seen, this is "top five" in worthless. ALL it possibly can do is provide a false sense of security.

If you're on a bike or a motorcycle, you're a vulnerable target. No two ways about it. A rear-looking radar/lidar is not going to help. Unbelievable.
 
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RCinNC

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How would a unit like this behave in traffic on a multi-lane highway, where there's the constant presence of traffic coming up behind you and passing you? Riding on a multi-lane highway seems like the one time where a proximity warning system to augment your side mirrors might come in handy, since it might tell you that someone was in your blind spot when you were about to change lanes, but that sounds like the type of environment where this sort of alarm would be going off constantly (which kind of negates its usefulness).

I ride a bicycle, and I can see some of the value of having this when you're on a slow moving vehicle relative to the other traffic on the road. It can be tough at times to hear an approaching vehicle when you're on a bicycle, so if you had an alarm like this, you'd have an early warning that a car was coming and you could ease over towards the shoulder for a little more of a space cushion with the approaching car. I'm not sure that I see the value of it to a motorcycle rider who's riding down a two lane road at the speed limit. Even if you had a warning that a car was quickly approaching you from behind as you're riding down the road, how would that affect the way you were riding? Would you suddenly swerve onto the berm or something?

I'm not knocking the concept; I'm just not sure what value it provides to a motorcycle rider that isn't provided by a pair of properly adjusted side mirrors.
 

TomZ

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It is amazing to me how much negative comment the idea of using the rear radar to detect vehicles coming from behind has generated. Most of the comment can be summarized as "my trusty old side vision mirrors are good enough for me." Personally I think the rear radar a great idea, and here's why. As a motorcyclist I want to be alert to what's going on around me all the time -360°. The motorcycle has 3 blind spots, not just the one on either side but also a much larger one behind the rider. In a car, we have a rear-vision mirror and would not think of relying solely on the side mirrors to see behind us. I use the rear radar system basically as a rear vision mirror that the motorcycle inherently lacks. I can see cars coming from more than 400 ft behind and judge how fast they are approaching. Also I have the display in front of me where I can see it without having to constantly check the side mirrors. That lets me focus on what's happening in front of the bike and to the sides while being aware of what's happening behind. If I see cars coming up and passing into the side blind spots, I can check them with the side mirrors just as I would in a car. Seeing a car appear way back might also help me avoid a speeding ticket.

To a certain extent, the rear radar system also shows vehicles in the side blind spots. I would not rely on it for that, but it helps. Several motorcycle manufacturers have started to incorporate side blind spot detectors: Dukati, Triumph, KTM and Kawasaki either have BSDs or have announced plans for them for certain models. These side blind spot detectors for motorcycles (as on many cars) are very different from a rear radar. They work at much shorter short range and they serve a different purpose to warn the motorist of unsafe lane changes. Dukati has a Utube video showing theirs in operation, with indicator lights at the top inboard corners of the side mirrors. Having the blind-spot indicator lights appear directly in front of the rider would be a lot better. Kawasaki also recently announced plans to have rear blind spot detectors (one on each side) as well as side BSDs. Rest assured the factory add-ons will be very pricy.

As to comparisons with bicycle riding, motorcycles and bicycles have very different safety issues. The motorcycle can easily accelerate to match or exceed the speed of traffic when riding on single or multi-lane highways. In contrast the bicycle is generally much slower than traffic and is constantly being passed. Good luck to the gentleman bicycle commuter from Montana where highway speeds are up to 80 mph. I feel much safer on motorcycle. With the rear radar system, the motorcyclist has a better chance to detect a potential rear end collision and avoid it.
 

WJBertrand

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I wonder what radar band it uses? I think some kind of rear warning system is good idea. How many folks remember to ALWAYS check their mirrors EVERY time you stop? I know I’ve had cases where I saw no one behind me as far as I could see when I stopped, only to notice someone there a moment later! Where the heck did they come from??

Getting back to the radar band question, if it uses an X, K or Ka band, they could be a bit of nuisance if your riding group runs radar detectors.



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Checkswrecks

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If somebody wants to run pink paint, fuzzy dice, and handlebar twirlers - I'm glad it makes them happy. Heck, even if it's a beak on a Super Tenere it makes them happy with their motorcycle so that's just fine.

As for the radar thingie, I can see it being a benefit for bicyclists around here. Most ride along the edge but every now & then they swerve with no freaking warning into the middle of a land to avoid some roadkill or bad pavement. If something warns them not to, that's a good thing for everybody involved. Cars with blind spot warnings get slightly lower insurance rates for a reason and I can't see why the improvement wouldn't be just as applicable for a motorcycle.

So while I'm not rushing out to install one I sure am open to anybody who wants to.
 

Lstayner

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Sep 18, 2020
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Central IA
I bicycle commute from August until May in Bozeman, MT. (I only work summers now.) previously, i've bicycle commuted year round for ~35 years in Minneapolis and in Iowa.

The problem with this is WTF are you gonna do on bike if you're gonna be hit from the rear? You can't accelerate, which leaves run off the road IF there's not a curb. Neither is a good option.

Beyond that, how do you accurately measure the trajectory of the vehicle approaching and estimate that it's going to collide with you? (I worked on ADAS/Autonomous vehicles for 25 years before moving here, so i know how lidar/radar work and perform.)

Cars pass me with 2' of clearance (often less) all the time. How is radar and the integrated signal processing going reliably estimate a crash?

Of all thing things I've seen, this is "top five" in worthless. ALL it possibly can do is provide a false sense of security.

If you're on a bike or a motorcycle, you're a vulnerable target. No two ways about it. A rear-looking radar/lidar is not going to help. Unbelievable.
One of the reasons I quit riding bicycles is when a cement truck passed me without moving over at all. Scared the crap out of me. Now I would only ride on a bike path even though state law requires drivers to give the full lane to a bicycle.
 
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