Speed and the fear of falling off

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Peter F
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Joined: 25 May 2020, 8:16am

Speed and the fear of falling off

Postby Peter F » 1 Jun 2020, 10:03am

So yesterday I hit a cats eye and suffered two punctures and a bent front rim. The front tyre went down pretty quickly but fortunately not fast enough to cause me to lose control and come off. I was mid bend, going down hill are had just hit 40mph when it happened. The surface is high grip so had I come off it would have been very nasty.
Once the the initial annoyance at the damage had worn off I started to think a bit more about how I was actually lucky to have stayed on the bike and not been injured, or worse.
Since returning to cycling back in 2012 my confidence in what the bike can do has grown and I now find myself getting to some fairly high speeds on descents. I can hit 45mph on the way to work. However an I pushing my luck?
I'm interested to understand how other road riders feel about this. How far are you willing to push and how much does comming off worry you?
Below is the bend in question
Screenshot_20200601-094907_Maps.jpg

Tangled Metal
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Re: Speed and the fear of falling off

Postby Tangled Metal » 1 Jun 2020, 10:20am

When I moved up here I had a regular loop with a long downhill that I could easily top 50mph. I used to try and beat my 58mph top speed. Did it twice there and when younger I did 58mph on a hill towards great Harwood IIRC. I never bested that but regularly got 54 to 56mph. All on typical, very rough country roads!!

Now I keep it to below 35mph Indeed I rarely get that fast these days with family cycling my main activity. Either way I could never get close to 50mph because I've learnt to fear those speeds. I was in my twenties with a lower perception of risk than now. Plus I was into whitewater kayaking and even dabbled in canoe polo. So my hand eye coordination and reaction speed was faster than now. It's very possible that I could survive stuff then that my slower reactions and dulled coordination would wipe me out now. I've lost those reactions because you do with age and without practise or training that demands that coordination.

Fear is good and bad. You need to control it but learn to understand what it's telling you. Enjoy your fast riding but be aware of the risks. Good assessment and hazard awareness is good. Were you going to fast try react and avoid the cats eyes for example. On my fast hill I once encountered a car whose driver hesitated then came out then stopped half out. I only just got round the bend avoiding his car. I never went as fast there again. I scared the whatsits out of me then. Going around the bend an inch away from the car at speed was now a risk I wasn't happy living with.

Now speed isn't where my fun comes from. We change with time.

mikeymo
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Re: Speed and the fear of falling off

Postby mikeymo » 1 Jun 2020, 10:50am

I don't cycle faster than about 25 mph. Even then only if I know the road, and it is clean and dry, with a good surface, little or no traffic, and few or no junctions.

A doubling in speed from 10 mph to 20 mph results in a trebling of stopping distances, from 6m to 18m, on a dry road with a 5% downhill gradient, if the rider is "alert", according to John Franklin in Cyclecraft.

This calculator:

https://www.exploratorium.edu/cycling/brakes2.html

gives quite different raw figures. I wonder if it is not including reaction time? As it gives a stopping distance of 1.15 metres at 10 mph, I assume it is just measuring the braking effect.

However, it does allow us to compare the ratio between speeds of our choosing.

Let's make my usual maximum speed 22.5 mph (half of yours). On a dry road the calculator above gives me a stopping distance of 5.85meters.

At your maximum speed of 45 mph a stopping distance of 23.41. That's a ratio of 4:1

To be honest both of those look way too optimistic. At 22.5 mph I might, just, be able to stop in 5.85 metres, assuming perfect braking technique and road surface.

More here:

http://www.muggaccinos.com/Liability/BrakeCalcs/Braking_formula/TwoDistanceToBrakeToStopFormulae.htm

Which I don't really have time or that much interest to study in detail.

One thing seems true though, that there is non-linear relationship between speed and stopping distance. Mathematicians, feel free to contradict/correct my observation.

I wouldn't ever cycle on a public highway at 45 mph. Perhaps an indoor velodrome or similar, where coming off the bike might not result in life changing injuries.

We all have a different attitude to risk, or course.
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Cyril Haearn
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Re: Speed and the fear of falling off

Postby Cyril Haearn » 1 Jun 2020, 11:13am

40 mph is much too fast to cycle
I get my kicks going uphill :wink:
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roubaixtuesday
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Re: Speed and the fear of falling off

Postby roubaixtuesday » 1 Jun 2020, 11:13am

Peter F wrote:So yesterday I hit a cats eye and suffered two punctures and a bent front rim. The front tyre went down pretty quickly but fortunately not fast enough to cause me to lose control and come off. I was mid bend, going down hill are had just hit 40mph when it happened. The surface is high grip so had I come off it would have been very nasty.
Once the the initial annoyance at the damage had worn off I started to think a bit more about how I was actually lucky to have stayed on the bike and not been injured, or worse.
Since returning to cycling back in 2012 my confidence in what the bike can do has grown and I now find myself getting to some fairly high speeds on descents. I can hit 45mph on the way to work. However an I pushing my luck?
I'm interested to understand how other road riders feel about this. How far are you willing to push and how much does comming off worry you?
Below is the bend in question
Screenshot_20200601-094907_Maps.jpg


I wouldn't regard 45mph as excessive per se, but certainly a speed which should be treated with respect. If you hit something at 40mph hard enough to bend a rim, then you're at high risk of coming off.

It's really important to ride within your confidence and capability. Don't ever feel "on the edge", err on the side of caution. Don't try to beat maximum speeds on downhills. Take account of the conditions, road surface (cateyes!) and other road users. There are many roads I can think of where 45mph would be the height of stupidity, but others where it is very safely achievable, but just for instance, I would never go that fast on a wet road. Others appetite for risk and skill level would doubtless be different.

But remember, most risk is at junctions, from motorists - that's where you really need to be concentrating.

All purely my own opinion.

roubaixtuesday
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Re: Speed and the fear of falling off

Postby roubaixtuesday » 1 Jun 2020, 11:19am

mikeymo wrote:I wouldn't ever cycle on a public highway at 45 mph. Perhaps an indoor velodrome or similar, where coming off the bike might not result in life changing injuries.


Ha ha - you're a obviously a much better sprinter than me (this is not a high bar, mind). I no longer ride on the track, but never once bested 35mph when I did!.

mikeymo
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Re: Speed and the fear of falling off

Postby mikeymo » 1 Jun 2020, 11:21am

Here's an observation.

I wondered where Birk Brow Road is, in case I knew it. I don't.

Is that road the same now as it is in your Google Street View picture?

If it is - look at your Google Street View picture. You see that red car coming the opposite way (Suzuki mini 4x4 maybe)? It doesn't go straight on. It does a U-turn through the gap just before the crash barrier starts. Here's a picture from the opposite direction.
Image I assume the gap is designed to allow down hill traffic to turn right, but unfortunately allows U turns.

So somebody in a sports car realises they've made a mistake and needs to turn round quickly. They are low down so their vision of oncoming traffic may be impaired by the crash barrier and the many signs in the central strip. In fact they may barely be able to see anything. Especially a cyclist in the drops trying to get up to speed. Plus wearing the "cyclists' invisibility cloak". They're not really paying attention, because they've just remembered they left the gas on so need to get home fast, hence the U-turn. Even if they can see, that's a bend you're coming out of. In fact, just looking at it now, for traffic coming from the opposite direction, who may or may not decide to make a sudden U-turn, visibility is even worse, as your side of the carriageway is lower down. You might very well literally be invisible coming down there. But you would know, maybe you also sometimes drive the road in the opposite direction. How much of a cyclist (or something the same height) can you see?

Just put yourself in the place of that Suzuki driver. I think a U turn there is dangerous (for a cyclist coming the other way) even if the driver is alert and takes care. If they're not, well...

As a driver I hardly ever make U turns. I think they're way too dangerous (whether that is supported by evidence or not I don't know). But the disturbed vision, during a U turn, the way that nothing you see in the mirrors is any use during the manoeuvre, yuk. Plus they're really confusing for other drivers. I'd rather drive a long way out of my way, and find another way to turn round.

If I'm ever cycling down Birk Brow Hill I'm going to go very very slowly.

Just a thought.
Last edited by mikeymo on 1 Jun 2020, 11:32am, edited 2 times in total.
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whoof
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Re: Speed and the fear of falling off

Postby whoof » 1 Jun 2020, 11:30am

Everyone is different and will perceive risk in a different way.
Cyclists that i know and have had serious injury; broken ribs,collar bones, legs, pelvis and vertebra and a couple who have been killed. Every one had the same cause, being hit by motor traffic either from behind or the side. My last off was about two and a half years ago travelling at about 10mph and hit by a car.

mikeymo
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Re: Speed and the fear of falling off

Postby mikeymo » 1 Jun 2020, 11:34am

roubaixtuesday wrote:But remember, most risk is at junctions, from motorists - that's where you really need to be concentrating.


Yes indeed. See my in-depth analysis :wink: of that very junction.
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roubaixtuesday
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Re: Speed and the fear of falling off

Postby roubaixtuesday » 1 Jun 2020, 11:36am

mikeymo wrote:
roubaixtuesday wrote:But remember, most risk is at junctions, from motorists - that's where you really need to be concentrating.


Yes indeed. See my in-depth analysis :wink: of that very junction.


Yup, I'd take speed off way below 45mph before a junction of any kind unless a very clear line of sight showed it empty of all traffic.

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squeaker
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Re: Speed and the fear of falling off

Postby squeaker » 1 Jun 2020, 11:42am

I no longer see the point of 'pushing' downhill. That said I probably do take risks on known roads. In particular, a hill close to home: it will either be a heart attack going up it, or a crash coming down (there's a bumpy bend near the bottom). I once came around said bend at night to find some dark cattle wandering in the road - bit of a surprise :shock:
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mikeymo
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Re: Speed and the fear of falling off

Postby mikeymo » 1 Jun 2020, 11:51am

There are many warning signs coming down that hill:

Gradient, engage low gear, skid risk, farm traffic, right hand bend with side road, dual to single carriageway.

Image

And a 25 mph maximum speed.

I know speed limits don't, legally, apply to cyclists. But maybe all that signage is a bit of a clue, eh?
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[XAP]Bob
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Re: Speed and the fear of falling off

Postby [XAP]Bob » 1 Jun 2020, 12:22pm

Ate least as relevant is that to hit a cat's eye you weren't sticking to a lane, and with that junction coming up I'd really want to be in lane 1.

The risks on a bent trike are somewhat different, and I'd be happy doing 40+ down that road from the looks of it, but I'd be in the middle of lane 1, not near a cat's eye.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
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Mike Sales
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Re: Speed and the fear of falling off

Postby Mike Sales » 1 Jun 2020, 12:34pm

I was descending the north side of the Crimea Pass, where I have hit 54 mph because I was happy with the run out.
I moved into the other lane to overtake another rider, and once I was past the cat eye spacing closed up. I did not feel sure of crossing back in a gap so I had to stay there until the cat eye gaps lengthened.
Getting a speed wobble on the same descent was probably my most frightening time on a bike.
I have managed to survive into pension age without an off at speed, in spite of enjoying letting gravity take charge, so perhaps my judgement was good. Or my luck.

tatanab
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Re: Speed and the fear of falling off

Postby tatanab » 1 Jun 2020, 12:37pm

mikeymo wrote:And a 25 mph maximum speed.

I know speed limits don't, legally, apply to cyclists. But maybe all that signage is a bit of a clue, eh?
That is not a speed limit. It is an information sign showing a recommended maximum speed.