Black ice

General cycling advice ( NOT technical ! )
samsbike
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Black ice

Postby samsbike » 2 Jan 2017, 9:23am

I try and commute on the bike. However I also keen to avoid ice as the cycle paths are not gritted.

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?

Thanks

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MLJ
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Re: Black ice

Postby MLJ » 2 Jan 2017, 9:30am

Black ice happens when a wet road freezes. If the road has been dry then a frost on it is white and often not slippery.

Vorpal
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Re: Black ice

Postby Vorpal » 2 Jan 2017, 9:34am

If it has been dry, it's generally okay, as long as you stay away from the edges and stick to where the cars go (i.e. ride in the inside wheel rut).

That said, I've set out occassionally, and found that conditions changed as I went. Once, I set off in good, but cold conditions, and when I got 4 or 5 miles from home, it was like I'd ridden into an new, and very icy country. I ended up riding to the next station and taking the train most of the way.
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eileithyia
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Re: Black ice

Postby eileithyia » 2 Jan 2017, 9:49am

If you have a regular commute it is always a good idea to learn where water tends to pool, ie I used to have a gentle left hand bend in front of some cottages on a camber, there was often water there as the drains never worked....... this could be spread across the road by cars which then meant it was a thin enough layer of moisture to freeze........ always kept as wide as possible near the centre or on the centre line......

I never used cycle lanes on icy mornings... and kept out from where the drains are etc........
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Cunobelin
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Re: Black ice

Postby Cunobelin » 2 Jan 2017, 9:55am

Listen, because the best indicator is your tyre noise.

You need know your bike, but basically if it starts hissing then it is frosty, but if the noise disappears then you are on ice

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Cunobelin
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Re: Black ice

Postby Cunobelin » 2 Jan 2017, 9:56am

.... or buy.a recumbent trike and solve the issue entirely

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freiston
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Re: Black ice

Postby freiston » 2 Jan 2017, 11:17am

My back wheel was spinning on the ice faster than I was travelling, going up a bit of a steep hill on Thursday - the only stretch on that ride where it happened - a lot of trees overhang the road there, which I reckon is where the moisture dripped from before freezing.
Disclaimer: Treat what I say with caution and if possible, wait for someone with more knowledge and experience to contribute. ;)

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Erudin
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Re: Black ice

Postby Erudin » 2 Jan 2017, 12:25pm

My experience is black ice gets you when you don't expect it to be there. In the circumstance of the o.p. I'd use studded tyres to be safe.

reohn2
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Re: Black ice

Postby reohn2 » 2 Jan 2017, 4:35pm

Erudin wrote:My experience is black ice gets you when you don't expect it to be there.

Yep that'll be right.
I fell a couple of weeks ago on black ice,didn't see a thing,didn't stand a chance.
Upright one second sprawling on the road the next,with a sore hip,elbow and sprained wrist.
In the circumstance of the o.p. I'd use studded tyres to be safe.

Or don't ride when it's below 3degrees C.
Better being safe than sorry IMHO.
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PhilWhitehurst
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Re: Black ice

Postby PhilWhitehurst » 2 Jan 2017, 4:36pm

Wet day followed by cold night are the days to avoid. Otherwise on a regular commute you'll be fine. On a country lane ride on the gravelly bit in the middle, camber means water drains to edge. Watch out on bridges as well, cold air underneath means they can be icy when everything else is fine. On a regular commute you'll know where a lane takes drainage and may be icy. If wheels start slipping don't be afraid to get off and walk for a few hundred yards. Icy stretches are rarely all that long.

tony_s
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Re: Black ice

Postby tony_s » 2 Jan 2017, 4:50pm

Black ice is horrid. It occurs when supercooled water droplets, be they rain or mist, come into contact with the road surface (or any other surface) and instantly solidify. "Supercooled" means still liquid but below freezing point, an unstable state that reverts to solid at the least provocation. Although the result is just ice, this particular deposition is near impossible to see, being the very thinnest of films around the road grit, hence the name. You usually don't see it, even when you look at it. When you run onto it it's just like having the bike kicked out from under you. Then you try to stand up and find you can't, not (only) because you're hurt but because the road feels as though it's covered in oil. Been there, done that, not recommended.

None of which is to minimise the hazard of any ordinary ice such as frozen puddles or hoar frost...

thirdcrank
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Re: Black ice

Postby thirdcrank » 2 Jan 2017, 5:02pm

If you are commuting, I presume you are using the same route regularly. In addition to eileithia's advice about watching out for the regular frozen bits, I'd pay attention to the gritting system, although if the Madeley's have not been stuck on the motorway recently :wink: , gritting is vulnerable to cutbacks. Policy varies with different highway authorities.

Typically, through routes especially bus routes are gritted. Side street generally are not. Look out for unexpectedly ungritted bits (eg because the gritter deviates and resumes further along.) Modern gritting techniques tend to apply a much finer spread than used to be the case, to the extent that the grit may not be obvious. The idea is that the passage of traffic spreads it out and that's why there's a marked difference between the part of the road taking the general run of traffic and the rest. Although the grit is aimed at the carriageway, flecks can reach the footway where they are visible as small dark spots against any surface frost. When turning off a through route, be alert to the likelihood that grit from the main road will be spread for a short way by vehicle tyres when that road has not been gritted.

With proper black ice, cars can be pushed about like giant curling stones.

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foxyrider
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Re: Black ice

Postby foxyrider » 2 Jan 2017, 5:23pm

Don't tense up if you think there's any chance of ice under your wheels - and stay sat in the saddle, if you are relaxed you will do less damage if you do hit the deck and you're less likely to hit the deck! Avoid braking at all if possible, but if you must certainly don't jam the anchors on and keep as straight a line as possible, any sudden change in direction is not good. Unclip your floor foot oh and run a bit less pressure in the tyres.

If only someone had given me this advice when I was fourteen! I've learnt all this the hard way and living where I do, I get plenty of chance to practice the techniques - the local snow/ice line is 50m below my domicile - it can be a full 5c difference down in the city to out here 200m higher on the edge of the Peak District !
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gaz
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Re: Black ice

Postby gaz » 2 Jan 2017, 5:29pm

January forecast is for a sustained period of cold frosty mornings. Studded tyres fitted to the commuter and I will continue to ride with care.
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Elizabethsdad
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Re: Black ice

Postby Elizabethsdad » 2 Jan 2017, 5:39pm

Cunobelin wrote:.... or buy.a recumbent trike and solve the issue entirely

Well, not quite entirely. I remember doing some rather impressive fish tails when I rode a 'bent trike in icy conditions.