Use cases for Garmin’s new traffic radar

In case you missed it, Garmin announced their Garmin Varia rearview bike radar, which signals the rider of traffic approaching from the rear.

Garmin Varia bike radar

There’s tremendous interest in this gizmo and I’m sure I’ll see at least a few on-bike radar devices after this product launches in October, but I’m curious: what is the actual benefit of a rear radar for cyclists?

Garmin Varia Bike Radar

Garmin purchased the assets of iKubu, a startup that attempted a crowdsourced bike radar they called the “Backtracker.” A number of gadget and fitness blogs have remarked on the amazing ability of Garmin to redesign and launch this product within six months. Garmin announced Varia this week, but actual product launch is scheduled for October. I’m on a design team for servers that sell for $50,000 and up, and these aren’t your basic low-cost rackmount units using generic reference designs; if we can’t get product out within ten months, we cancel the project. But I digress.

Alien motion detector

Garmin’s marketing copy capitalizes on fear from the rear. The threat is real. That’s why getting some extra help knowing what’s sneaking up behind you is an important breakthrough.” Is this useful in preventing hit-from-behind collisions? Although hit-from-behind are very rare, this is indeed the type of crash that is mostly likely to kill you as a cyclist in the United States.

The Varia device keys on micro-changes in air density to detect alien death creatures approaching from the rear. This information is sent to either the dedicated display unit designed for the Varia, or to a compatible Edge cycling computer via Garmin’s wireless ANT+ interface. This display shows the relative speed, distance, and “threat level” (Garmin’s words, and good grief) of approaching chestbursters, predators and motor vehicles so you can jump out of the way or take other countermeasures.

Aliens Colonial Marines

Use cases?

I still don’t see how you’re supposed to know when a car will hit you. Although several people online have already commented on the questionable utility of this bike radar, Garmin obviously believes there’s a market for this device.

Varia has a more useful feature that Garmin doesn’t talk about as much: the tail light unit included with the radar flashes brighter and faster as the vehicle approaches. When I’m taking the lane on a narrow road, I typically use the “slow down” hand signal when I hear traffic approaching quickly from behind me. I really like this flashing light feature.

But what about that display? Does it really help knowing there’s traffic approaching from behind? After all, isn’t that kind of our default assumption when cycling on the road?

I can think of five scenarios where this bike radar might be helpful.

  1. Two abreast riding. You and your buddies are riding two (or more) abreast on an otherwise empty shareable road. The bike radar signals “car back!” and everybody moves over to ride single file. When the way is clear again, you can ride two abreast and resume your conversation.

    Aliens Ripley

  2. Stiff neck. You have a left turn or you need to merge left up ahead in possibly busy traffic. A stiff neck makes the head check difficult, so instead of constantly scanning back to look for that gap in traffic, maybe you can glance down at your M314 motion detector for the gap, then do your head check to confirm the gap and perform your merge.
  3. Sometimes I play in traffic. This has happened to me: I’m on a country road with no traffic and I’m riding very slowly while shooting bike selfies or otherwise goofing off in the middle of a shareable lane. While riding no-handed, I check my self-portrait on the phone and notice the car behind me, with the driver waiting patiently for me to get out of the way. Ooops!
  4. Seat warmer. Radar operates in the microwave band. Point that up and a little forward on a cold day and warm your tush!
  5. Traffic calming device. I don’t know which specific band Garmin uses, but if it uses one of the police radar bands, maybe you can trigger the radar detectors in every car behind you, encouraging these drivers to slow down. If a different frequency band is used, how hard would it be to hack one of these units to transmit on a speed gun band?

These can be handy functions, but is it really worthwhile to spend $200 to $300 for functionality that can be performed equally well with bicycle mirrors?

Interesting product with possible benefits, but color me dubious.

DC Rainmaker got his hands on an advance review unit and gives what seems to be good review.


  1. Now if they could add in a real radar detector for finding those ranger speed traps up on the MTB trails, fire roads and MUT paths, they might have something. I even sent a feature request to Garmin about putting in some sort of audible speed indicator to sound if a certain speed (like 15 MPH) was exceeded but do date have heard nothing about that. Save one bike speeding ticket and you could pay for the device.

  2. I like the “hack it to set off radar detectors” idea. I’m thinking that Garmin is having *lots* of meetings to try to find features you can’t get on a phone app… but wonder how many actual riders they asked about this one.
    Now, if they had airbags that came out *behind* your seat, we might have something to talk about…

  3. I am not sure this gives any more benefit than a $10 clip-on mirror. Which also has the advantage of being battery-less.

  4. Might have a minor benefit:

    The qualities of Fredliness:
    1. Rides in a T-shirt
    2. Has a rear-view mirror attached to his/her helmet
    3. Has mountain bike pedals on a road bike
    4. Has a kickstand
    5. Wears safety glasses instead of Oakleys
    6. Uses goofy “Trekking” handlebars
    7. Rides a frame far larger than an elite racer would ride
    8. Sets the handlebars up so they are as high as the seat

    Of course having a $300 rear view radar on a $200 bike might negate the Fred-reducing benefit of no rear view mirror 😉

  5. Hey RBrown,
    Come ride on the streets of L.A. you will grow to love a mirror on your helmet!
    Better a Fred then Dead! Haha!

  6. 7 years later, it turns out the Garmin Varia radar is an excellent device. I never go road biking without it. It’s very sensitive and tells me how many cars are behind me, their distance. It even shows different colors for their rate of speed. (red for fast approaching). The cyclists I ride with consider it one of their best ever bike purchases, and so do I. It even senses other cyclists approaching at a faster speed.

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