Rear radar - any good?

[PaulSB]

Fair. I guess the timing of signal before manoeuvre is driven by the time it'll take to reach the junction and this trumps waiting till there's no vehicle behind. As for "no point in shoulder checking till the vehicle has passed" I reckon, perhaps it's my wishful illusion, that the movement of a rider's deliberate look behind increases most drivers' focus on the obstruction ahead and deliberate passing (or not) with due care. Rear radar offers info on what's behind. Whether that's actionable info is moot. We've all been surprised by 'quiet' passes: info from rear radar reduces that surprise.
Mike's "turning off the A61" (right) sounds like a niche case.

I would agree with this. I feel attempting to make eye contact with the driver can have a significant influence on the driver's actions. I use the technique in many situations as a matter of routine. I'm told, by an ex police officer, it's part of the driving skills taught to all police drivers.

 

[PaulSB]

Looking at a head unit takes your eyes off the road on a drop bar bike. Where as visually with a mirror you can process both forward and rear views at same time.

I don't agree with this. My head unit position is such the radar warning light will catch my eye, glancing at the screen is no different to checking a rear view mirror. One can also have an audible alert. I don't because it's a potential irritation to those around me.

A friend I ride with uses a mirror that to my mind is incorrectly positioned. She slightly drops her head and looks down to the right. I've seen her ride into the back of another rider who slowed while she mirror checked.

Clearly several things wrong there but my point is a correctly positioned head unit or mirror can be seen without losing concentration. Incorrect positioning of either will distract the rider.

 

[HLaB]

Yes I get all that and agree the advance warning is good to stop the sudden fright of a speeding car going past but my point is it doesn't do any more than a mirror as it won't help in a close pass situation, that is the cyclist is still as vunerable and exposed to danger. I've had instances on a road where cars have gone past me at 60mph+("quiet" A roads which are good to cycle but cars able to drive fast) so even if I see them approaching from behind you never know how they will pass you as they are upon you and past so quickly especially if it's an incline and I'm doing say 15mph max in comparison.

Again, I'm not trying to downplay or be negative about the radars, just wondering about effectiveness to keep me safe.

Anyway, it's club ride today so unless I bail due to forecast I know the ride leader is a recent advocate of rear radar so I'll also quiz him on it.

Probably too late today but multiple users can connect to one Varia, you could ask the ride leader if you can connect to his or somebody else's in the group if you have an ant+ head unit.

 

[PaulSB]

Probably too late today but multiple users can connect to one Varia, you could ask the ride leader if you can connect to his or somebody else's in the group if you have an ant+ head unit.

Oh, we've had fun and games with that sort of thing. The best to date is when I connected to my buddy's HRM, his HR is generally 30bpm higher than mine. 🤣

 

[Alex321]

Looking at a head unit takes your eyes off the road on a drop bar bike. Where as visually with a mirror you can process both forward and rear views at same time.

You ill see the orange flash in your peripheral vision, you don't need to take your eyes off the road for that.

 

[cougie uk]

Probably too late today but multiple users can connect to one Varia, you could ask the ride leader if you can connect to his or somebody else's in the group if you have an ant+ head unit.

This is how my pals got their radars. I jumped first with just the sensor and they would connect to me on the sunday rides.
After two weeks they both had their own.
Go for the radar & light though - the battery life on that is longer than just the sensor.

 

[freiston]

I've only read the first page and this last page. I've been on a few rides with people with the rear radar and my anecdotal observation is that generally, with my hearing and my rear view mirror, I am aware of motor vehicles approaching from behind before the rider with the radar is. I haven't investigated why. I suspect that I'm seeing/hearing them before the vehicle is in radar range, and that the rider with the radar isn't looking or listening out, instead relying on their computer screen to indicate the vehicle.

 

[HLaB]

I've only read the first page and this last page. I've been on a few rides with people with the rear radar and my anecdotal observation is that generally, with my hearing and my rear view mirror, I am aware of motor vehicles approaching from behind before the rider with the radar is. I haven't investigated why. I suspect that I'm seeing/hearing them before the vehicle is in radar range, and that the rider with the radar isn't looking or listening out, instead relying on their computer screen to indicate the vehicle.

Do you actually know they haven't been aware; they might have been aware but just not needed to look back or alert the group to a cars presence until it was closer and they have a better picture of its approach speed (threat level). And were able to keep looking forward all the time, I'd only look back when I want to do a manoeuvre and if in a group only alert them to an actual threat I think most good radars have a detection range of 150m which is ample for me and there's no blind spots.

 

[geocycle]

I've only read the first page and this last page. I've been on a few rides with people with the rear radar and my anecdotal observation is that generally, with my hearing and my rear view mirror, I am aware of motor vehicles approaching from behind before the rider with the radar is. I haven't investigated why. I suspect that I'm seeing/hearing them before the vehicle is in radar range, and that the rider with the radar isn't looking or listening out, instead relying on their computer screen to indicate the vehicle.

Hearing is indeed really important and probably my main way of detecting vehicles behind. I often hear something before the radar sees it, at other times I hear an unattributable noise and then the radar confirms if a vehicle is approaching or not. There are some instances where road noise and wind means the radar is ahead of the game.

 

[Mike_P]

My Varia certainly detects vehicles a fair distance behind well before its heard over the noisevid traffic in the opposite direction and the wind. Thats probably why the resulting speeded up flash rate has not lead to anyone being challenged on having a light with a variable flash rate.

 

[freiston]

Do you actually know they haven't been aware; they might have been aware but just not needed to look back or alert the group to a cars presence until it was closer and they have a better picture of its approach speed (threat level). And were able to keep looking forward all the time, I'd only look back when I want to do a manoeuvre and if in a group only alert them to an actual threat I think most good radars have a detection range of 150m which is ample for me and there's no blind spots.

No I don't; it did cross my mind that they might be waiting until the cars were closer but I couldn't determine anything to suggest either way except that I thought some of the warnings were late. Your info on range might have a bearing too. On one ride, where I particularly noticed that the (nominated on an organised ride) rear rider with the radar wasn't giving (imho) timely warnings was when we had to go onto a very fast single carriageway A road - the sort that often has double white solid lines in the middle. By my reckoning, vehicles travelling at 60-70mph would only be in range about 5 seconds before they would be overtaking (and less before they start their manoeuvre to give passing space). I suspect that some cars were travelling faster before coming into range.

 

[lazybloke]

I don't deafen myself with headphones or straps that catch the wind over my ears.

I've heard a suggestion about straps causing noise, but have never experienced it.

Simple test: find suitable long downhill and acquire sufficient speed for wind noise 'from straps'. Here comes the dodgy bit: achieve appropriate balance, let go of handlebars to unclip and remove helmet; realise the straps weren't causing the noise at all. Attempt to put helmet back on.

(witnesses might hear an 'oh ####!' as a cyclist suddenly rides into a hedge).

Back to topic: i have just about enough flexibility to look behind me when cycling, but usually hear cars before they're visible thanks to my preference for low-traffic roads. Even so, i'm occasionally surprised by overtaking cars, and that's something i really don't like. Haven't been tempted by radar yet, but i like the concept.

 

[Psamathe]

... that the movement of a rider's deliberate look behind increases most drivers' focus on the obstruction ahead and deliberate passing (or not) with due care.

Maybe also tells the driver that you have seen them (even without eye contact). A lot of my cycling is on narrower/single track roads so I do end-up pulling in to let cars pass (when convenient) - I'd rather have a happy driver in front of me than a frustrated driver behind me. Of course a lot depends on the nature of the roads and where there is space (roads wide enough) the driver behind can wait for clear visibility ahead. Just on narrower roads with fair distance to any opportunity for a safe pass I'll make the effort.

 

[Webbo2]

No I don't; it did cross my mind that they might be waiting until the cars were closer but I couldn't determine anything to suggest either way except that I thought some of the warnings were late. Your info on range might have a bearing too. On one ride, where I particularly noticed that the (nominated on an organised ride) rear rider with the radar wasn't giving (imho) timely warnings was when we had to go onto a very fast single carriageway A road - the sort that often has double white solid lines in the middle. By my reckoning, vehicles travelling at 60-70mph would only be in range about 5 seconds before they would be overtaking (and less before they start their manoeuvre to give passing space). I suspect that some cars were travelling faster before coming into range.

Going off subject. Cars shouldn’t be overtaking you where there a solid double white lines unless of course you were travelling at less than 10mph.

 

[freiston]

Strictly speaking, they cannot cross/straddle the white line to overtake unless the vehicle (including bike) being overtaken is travelling at 10mph or less - but can overtake vehicles travelling faster than 10mph if they do not cross/straddle the line. There were opportunities on the road in question to overtake legally (whether due to lines, space or our cycling speed).