Black ice

General cycling advice ( NOT technical ! )
hamster
Posts: 3172
Joined: 2 Feb 2007, 12:42pm

Re: Black ice

Postby hamster » 20 Jan 2017, 6:31pm

Don't forget local variations, shadowed areas and frost pockets will always consistently differ from a forecast.

nez
Posts: 1607
Joined: 19 Jun 2008, 12:11am

Re: Black ice

Postby nez » 21 Jan 2017, 10:40am

Threevok wrote:
pwa wrote:Never tried the studded tyres, but thy sound like a bit of a faff, considering how few days of the year are icy around here. Maybe a better idea if you have a second bike that can be left with studded tyres on over the winter, to be used when in doubt.


There are indeed a faff, with the constant on and off - especially if you use them in conjunction with slime tubes. Also, some days, you just don't know what the conditions are going to be, until the morning - a bit of a rush to change them beforehand, if you commute.

As you mention, I have my second bike set up already, which is a lot easier. When I only had the one bike, I would leave the spikes on - from the beginning of November to the end of February.

Spare wheels night be a cheaper alternative. I've got my spiked tyres on an old set of wheels.


I'm a trendy consumer. Just look at my iPad using Tapatalk

nez
Posts: 1607
Joined: 19 Jun 2008, 12:11am

Re: Black ice

Postby nez » 21 Jan 2017, 10:45am

horizon wrote:
samsbike wrote:
What I am unsure about is when to expect ice. Tonight it's down to around -3c and then staying there or thereabout so tomorrow should be cold. Today it's dry so am I safe to assume that the likelihood of black ice is greatly diminished?



I went for a ride this afternoon in bright, cold, sunny conditions. The road was nice and dry and the forecast was for 6 deg. I reached the point where I know ice can form as water runs across the road from a hillside. And sure enough there it all was: across the road in thin sheets, in puddles by the side of the road and icicles hanging from the bank. This stretch of lane is in shadow for much of the day in winter. I turned back, albeit with some slipping and sliding (I had dismounted). This is southern Cornwall BTW at sea level, not Scotland.

My point is that I don't recall the forecast being below 3 deg overnight but I don't know how to check this (any ideas?). My rule of thumb is that if the forecast or actual temperature falls below 3 deg overnight for your area then the studded tyres are justified in the morning. A lot will depend on local conditions and whether you cycle on main roads but I presume the forecast is for the weather conditions at the local weather station and won't take into account shady or wet spots.

UPDATE:
I've checked the forecast on the Met Office website:
http://www.metoffice.gov.uk/public/weat ... rification
This gave a minimum of 1 deg so quite accurate but still not freezing.

Freezing conditions for road surfaces is considered to be plus 4


I'm a trendy consumer. Just look at my iPad using Tapatalk

Phileas
Posts: 192
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: Black ice

Postby Phileas » 21 Jan 2017, 11:17am

mjr wrote:Look at "minimum ground temperature" on forecasts like http://www.weatheronline.co.uk/weather/ ... NOREGION=1

Typically, it's at least 4°c below the air temperature given in the main forecasts, plus you can usually deduct another couple of degrees in winter for the countryside outside the given town.


But remember that this is wind dependent. The forecast "air" temperature is for 2m above the ground. In still conditions there can indeed be a 4C difference at ground level due to the ground radiating heat and the air stratifying above. In windy conditions, the air is being constantly mixed so cold air next to the ground is quickly replaced with milder air.

User avatar
horizon
Posts: 9551
Joined: 9 Jan 2007, 11:24am
Location: Cornwall

Re: Black ice

Postby horizon » 21 Jan 2017, 1:33pm

The problem is we don't really know. So do you take the studded tyres or not? I would say as a rule of thumb 3 deg (forecast air temp) is about right but people seem to be saying even 4 deg is worth thinking about. What we are all agreed on is that you don't need to wait for zero, which answers the OP's question.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

nez
Posts: 1607
Joined: 19 Jun 2008, 12:11am

Re: Black ice

Postby nez » 21 Jan 2017, 1:40pm

Given the difficulty of mounting them I would say changing tyres for the entire winter season is the trick, unless you have super thumbs. At least no one will be able to say 'I never heard him coming'

User avatar
horizon
Posts: 9551
Joined: 9 Jan 2007, 11:24am
Location: Cornwall

Re: Black ice

Postby horizon » 21 Jan 2017, 2:00pm

nez dans le guidon wrote:Given the difficulty of mounting them I would say changing tyres for the entire winter season is the trick, unless you have super thumbs. At least no one will be able to say 'I never heard him coming'


For a short commute or a trip to the shops, I agree that it's worth just leaving them on. Someone else has suggested a spare pair of wheels (that's what I have) or even just an old mountain bike. People say that for the UK winter it isn't worth thinking about studded tyres but for all the anxiety and uncertainty caused by the possibility of ice, it seems a small price to pay. It's not as though cycling on studs is that bad - just a slower ride and a rumble. At least you get there in one piece and with an easier mind.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

nez
Posts: 1607
Joined: 19 Jun 2008, 12:11am

Re: Black ice

Postby nez » 21 Jan 2017, 2:03pm

Yes I put them on some old wheels so I can swap back and forth. The trouble is as you get older the results of falling off don't mend so quickly, so I've decided to err on the side of caution.

Phileas
Posts: 192
Joined: 18 Feb 2009, 6:12pm
Location: Bristol

Re: Black ice

Postby Phileas » 21 Jan 2017, 2:18pm

Yes, I bought a spare pair of wheels which I could "simply" swap as required. Unfortunately I didn't give it enough thought when I bought the wheels and ended up with rims which are significantly wider than the other pair so I have to fiddle around with the brakes when I swap over. :oops:

Vorpal
Moderator
Posts: 17190
Joined: 19 Jan 2009, 3:34pm
Location: Not there ;)

Re: Black ice

Postby Vorpal » 22 Jan 2017, 12:22am

I keep studded tyres on my winter bike, and any time there is a serious possibility of ice, I use it.

I have ridden my road bike a couple of times and discovered that it was icy a bit further from home. I just went cautiously, and took my time, and mostly stuck to the main roads. When it was on my way to work it cost me some time.

I've also ridden on studded tyres a couple of times when I didn't need to, and frankly I'd rather that, as much work as it is, than risk a fall.
“In some ways, it is easier to be a dissident, for then one is without responsibility.”
― Nelson Mandela, Long Walk to Freedom

robc02
Posts: 1658
Joined: 23 Apr 2009, 7:12pm
Location: Stafford

Re: Black ice

Postby robc02 » 22 Jan 2017, 11:16am

At the first sign of ice, usually in November, I fit my summer touring bike with studded tyres. I leave them on until around March. I am fortunate in having another winter commuter for when studs aren't necessary, but when in doubt I commute on the studs and put up with the slightly longer ride time.

There are one or two sections of my rural commute that are often icy even when the temperature at home is a few degrees above freezing. My old test of checking the garden bird bath and/or car windscreens for ice has let me down a few times so now I take the "better safe than sorry" view!

Ruadh495
Posts: 413
Joined: 25 Jun 2016, 11:10am

Re: Black ice

Postby Ruadh495 » 23 Jan 2017, 12:52pm

Got "black iced" this morning. Rode into work as normal (though the freezing fog was "interesting"), put the bike away, stepped outside the building and sat down rather suddenly. The shallow concrete ramp which serves as a doorstep was almost frictionless with an invisible coat of ice.

It can be lurking anywhere, and it'll get you even if you fit studs, it just waits for you to get off the bike. Seriously, though, if the back doorstep was iced I must have ridden over a fair bit of it, I used several lanes and cyclepaths that don't get gritted. Studs work.

Threevok
Posts: 195
Joined: 30 Sep 2016, 3:11pm

Re: Black ice

Postby Threevok » 23 Jan 2017, 1:04pm

Ruadh495 wrote:It can be lurking anywhere, and it'll get you even if you fit studs, it just waits for you to get off the bike


Wear studs on your feet also. 8)

User avatar
mjr
Posts: 13736
Joined: 20 Jun 2011, 7:06pm
Location: Norfolk or Somerset, mostly
Contact:

Re: Black ice

Postby mjr » 23 Jan 2017, 4:15pm

Threevok wrote:
Ruadh495 wrote:It can be lurking anywhere, and it'll get you even if you fit studs, it just waits for you to get off the bike


Wear studs on your feet also. 8)

The bargain shops have been selling ones that clip over shoes - although they might be selling out by now - but I've not tried them.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

Threevok
Posts: 195
Joined: 30 Sep 2016, 3:11pm

Re: Black ice

Postby Threevok » 23 Jan 2017, 7:21pm

mjr wrote:
Threevok wrote:
Ruadh495 wrote:It can be lurking anywhere, and it'll get you even if you fit studs, it just waits for you to get off the bike


Wear studs on your feet also. 8)

The bargain shops have been selling ones that clip over shoes - although they might be selling out by now - but I've not tried them.


Indeed. I use the single strap type myself