Rear radar - any good?

[PaulSB]

Agree with every word. Very comprehensive summary.

Thank you.

 

[Sea of vapours]

I suggest that seems like interpreting the code to support one's prior belief. The standard requires that you make effective use of the mirrors and checking them too often for the situation is likely to be as ineffective as not checking them enough.

Indeed, the standard says: 'make effective use of mirrors and other aids to vision to identify and monitor other road users and hazards'. Many people do interpret that as typically, 5-8 seconds. Personally, I think that's reasonable in many situations, but not all. I agreed on the 'not all' bit so you have nothing to disagree with there. I'll explicitly agree that checking mirrors over frequently - 90% of the time for example - would be highly ineffective for safely driving forwards. That's entirely obvious and really not worth stating, so I didn't.

Serious question: how strong does a headwind have to be to prevent sound transmission? And would many still be cycling into it?

Fair point. That would be literally 330 m/s, which is 'brisk'. The relative wind speed in a strong headwind, or a fast downhill, does, however produce a lot of wind noise so approaching vehicles are being masked, not the sound removed altogether. And some helmets will indeed make that worse, as you pointed out.

As I already asked, "what can you do anyway?"

Plenty of things, up to and including throwing yourself into the hedge / whatever. A couple of days ago, for example, I moved into a very strong primary position on a wide-ish B road, approaching a right hand bend, since I could see a line of vehicles coming towards me and the radar told me of a rapidly approaching vehicle behind. For whatever reason, I'd not heard it. it was 140m back when detected and I was concerned that it would move out to pass me and swerve back in, still at high speed, when it saw the oncoming line of traffic. I moved out; it slowed to my speed and passed safely afterwards. The very early warning from the Varia enabled this method. I don't know when I'd have heard it otherwise, but closer than it was, and quite possibly too late to move, rightward *into* the road. I might have had to move to the extreme left, which I'd not regard as desirable. That sort of thing happens relatively often; once or twice in a thousand kilometres or thereabouts.

On the large / small vehicle thing: I don't wish to be hit by a cyclist either. Many cyclists pass way too close and I'd like to know they're coming. They typically make very little noise too, so the radar is really handy in that respect. And that is also a good example of things even those with the very best human hearing can't hear.

They really aren't worth the cost and faff for many, but I fully support you using them, and it's great fun for others repeatedly racing up behind one and triggering the beeps, then dropping back to repeat.

I'm pretty sure nobody here suggested that they were 'worth the cost and faff' to everyone? I certainly didn't. They're a tool that some find useful and you don't, so do carry on not using one :-)

 

[mjr]

I don't have a problem. Got two mirrors (one each side) though as much to avoid moving them around in ferry ports (in UK left mirror of limited help).

A bit more limited with fully laden panniers but doesn't take much to lean a little and no problem.

Then you found a way to look behind you. Not all do.

 

[Dogtrousers]

It has, however, piqued my interest. A rear camera would have been useful but I'd never heard of a radar. Does anyone have one? Do they work? Or are they just another annoying bit of tech that has to be charged before every ride?

If it is/was a Garmin Varia with camera, the camera part of it got a pretty scathing review from DC Rainmaker (non image stabilised, crappy software). So there will be better cameras out there. Although Garmin may have improved it since the review which was a couple of years ago.
https://www.dcrainmaker.com/2022/05/garmin-rearview-bikelight.html

As to the Varia radar sans camera, as noted there are lots of threads.

 

[mjr]

I'm pretty sure nobody here suggested that they were 'worth the cost and faff' to everyone? I certainly didn't.

You replied to disagree with part of a post where I said exactly that before, so I hope my confusion was understandable to most readers.

 

[Sea of vapours]

You replied to disagree with part of a post where I said exactly that before, so I hope my confusion was understandable to most readers.

Ummm..... Do please read my most recent post again. There is no 'not' preceding the 'worth the cost and faff'. You most certainly did say something close to 'not worth the cost and faff' before, yes; no argument there. Nobody said 'they *are* worth the cost and faff, however. Various people merely expressed their liking for them to different degrees. And the part of your original post I addressed was that which I quoted, not the 'not worth it' aspect. As I said, please do carry on not using one!

 

[wafter]

A mate has one and swears by it; although we tend to be diametrically-opposed on many things bike...

Personally I don't see the point - if I'm going to manouver I'll look anyway, while simply knowing something is behind you doesn't really alter prospective courses of action or outcomes. Presumably these devices do nothing to suggest that a vehicle might be about to pass dangerously closely and even if they could there's not much you could do to avoid the consequences.

 

[Dogtrousers]

As is often the case with new things these tend to be appreciated by those who have used them, and deprecated by those who haven't.

My experience is that they can be handy for early awareness of vehicles behind that are out of hearing range or quiet (like other cyclists). They're not of much use in traffic-dense environments like towns.

It's just another piece of information.

There's no faff, beyond setting up the initial connection with the GPS. There is, undeniably, cost.

 

[PaulSB]

A mate has one and swears by it; although we tend to be diametrically-opposed on many things bike...

Personally I don't see the point - if I'm going to manouver I'll look anyway, while simply knowing something is behind you doesn't really alter prospective courses of action or outcomes. Presumably these devices do nothing to suggest that a vehicle might be about to pass dangerously closely and even if they could there's not much you could do to avoid the consequences.

I'm 100% with you regarding the need to look prior to making a manouevre, no device not even a mirror, on a bike, is a substitute for a shoulder check. The highlighted piece is where I need to correct your presumption. I'm using a Varia RTL515, light and radar, with a Wahoo Roam Gen 2. This is what I have displayed on the Wahoo screen, coloured band down the RHS and lights across the top:

• Solid green - clear road behind
• Solid green with car icon/green light flashes - vehicle behind
• The car icon gets closer as the vehicle does. While the vehicle is travelling at the same speed relative to mine it remains green
• Solid green changes to orange - the vehicle speeds up and begins to overtake
• Solid orange/orange light flashes/car icon - vehicle approaching at faster speed than my own
• Solid red/red light/car icon - vehicle approaching at high speed. Do the family know where the will is??
• If there is only one vehicle approaching one icon shows, more than one vehicle then multiple icons show
• As each status changes the device beeps

I feel this is comparable to the view I have in my car mirrors, see my next post to @Sea of vapours The warnings provided inform me a shoulder check could be necessary and/or I should take action. What that action is will be based on the road situation, shoulder check and perceived threat.

I've been using one for 6 - 8 weeks and had two red warnings in that time.

 

[PaulSB]

Many people do interpret that as typically, 5-8 seconds. Personally, I think that's reasonable in many situations, but not all.

Apologies but I don't have time to find your original post on the frequency of mirror checks while driving. I was out in rush hour this morning to collect my granddaughter on a mixture of A roads and motorway. I don't know why but I suddenly became aware of my mirror use which set me thinking about your posts on this. I realised with a slight sideways eye movement I constantly monitor both the rear view mirror and offside wing mirror. This doesn't need a head movement and is momentary, not enough to distract from what is happening ahead of me. I believe I'm fully aware of what is behind me perhaps 99% of the time. I also realised that when I prepare for a manouevre I move my head and take a longer look.

My nearside mirror seems to be mainly used when manoeuvring, primarily pulling in after an overtake.

I don't disagree with your figures but for myself I am checking many, many more times than you seem to suggest and I suspect it could be similar for many drivers. There are clearly those who aren't even aware a car comes equipped with a mirror!

This took me by surprise and without your comments I don't think I would have become aware of it. My actions have become instinctive.

 

[craigwend]

A cycling friend who is deaf has the flashing light / radar version and is quite invaluable for him. He also runs a social cycling group, so if he's at the front as he can't hear the 'car' (up/down/sideways etc) call can be helpful.
Personally I don't need one now, but could see how they could be helpful

 

[Marchrider]

As is often the case with new things these tend to be appreciated by those who have used them, and deprecated by those who haven't.

My experience is that they can be handy for early awareness of vehicles behind that are out of hearing range or quiet (like other cyclists). They're not of much use in traffic-dense environments like towns.

It's just another piece of information.

There's no faff, beyond setting up the initial connection with the GPS. There is, undeniably, cost.

I think I would find them useful on windy days, riding into a big wind makes you deaf to what might be about to pass, and I hate that.

I generally ride on very quiet roads and I like to watch every vehicle past, I hear them I know they are there, I hear them slow down, I would even claim to hear them move out to pass, what class of vehicle it is or if it has a trailer - but I always like to look back so they know I am watching them, this tactic seems to promote a far wider more careful pass, and if it is a type of vehicle that gaives me extra concern, a logging truck, a range rover, an audi, an idiot with a lunatic exhaust. I fully turn round to watch them, right hand on seat sort of look back! that really does make them drive carefully

so yes a radar for heading into the wind would be good

Anyway, on this perfect day its time to get on the road and knock some miles out

 

[Sea of vapours]

I realised with a slight sideways eye movement I constantly monitor both the rear view mirror and offside wing mirror. This doesn't need a head movement and is momentary, not enough to distract from what is happening ahead of me. I believe I'm fully aware of what is behind me perhaps 99% of the time. I also realised that when I prepare for a manouevre I move my head and take a longer look.

I concur on all that. That's exactly what you should be doing and I do the same. The 5-8 second thing is a guideline and probably comes with 'not less than ...' in most cases where it's stated. It's harder on a bike due to having to turn your head, and bike mirrors are considerably less good than car mirrors, if present. That's precisely why the radar helps, as you've said. It's simply adding another tool for constant situational awareness.

 

[PaulSB]

I concur on all that. That's exactly what you should be doing and I do the same. The 5-8 second thing is a guideline and probably comes with 'not less than ...' in most cases where it's stated. It's harder on a bike due to having to turn your head, and bike mirrors are considerably less good than car mirrors, if present. That's precisely why the radar helps, as you've said. It's simply adding another tool for constant situational awareness.

I've never used a bike mirror and only know two people who do. One of those is unable to physically turn and shoulder check. In this case I recognise it helps significantly but it also creates a danger. Riding behind it's very clear the individual looks down and to the right with a head movement. I've seen this result in failing to notice the rider in front has slowed quickly and ridden into the back of that rider.

I know this person well enough to raise the matter critically. I've been assured every possible mirror position has been tried.

 

[Sea of vapours]

That's certainly a hazard, yes, though presumably, if this person could look behind them 'properly' the same issue would apply if they did so whilst close behind someone else who then changed speed? As has been said, all these things are tools and using them correctly / safely is critical since using them poorly may be overall less safe.