Monday 9 September 2013


In my second to last post I discussed how visibility and speed contribute to the safety of your ride.

Today I want to say a bit more about speed.

First things first, say you are driving a car. Your perception of speed is compromised in a car, for a few reasons.

First, get out on the highway and get up to 100 km/hr or so. Then roll down all your windows.

LOUD and WINDY isn’t it?

Now, pull off onto a dirt road, feel the tires slide a bit, realize that your regular driving surface contributes to your traction and masks your speed.

Here’s another one. Look out the front window as you drive, you feel like you are moving placidly forward. Look perpendicular to your path and see the hedges or fences whipping by, suddenly you are very aware of your speed.

Look at the cars passing you. Relative to your speed, they are not moving that fast, perhaps 10 km/hr, but total speed they are going say 110 km/hr, very fast indeed.

So the car does several things to mess with your perception of speed:

1. It blocks the wind resistance making your environment calm and quiet.
2. It smooths out your contact with the road with tires and smooths bumps being on paved surfaces, both mask your speed.
3. It masks peripheral visual objects that would more accurately convey your velocity (you look forward for the most part when you drive).
4. Your available reference points (passing traffic) are moving slowly, relative to you, giving the perception that you too are moving slowly.

What does this mean?

Well, car drivers aren’t always that good at estimating how fast they are going, and therefore how far they require to stop. Physics doesn’t help either, as in addition to misestimating speed, we tend to underestimate the weight of the vehicles in question, and the greater the weight at a given speed the greater the momentum… and thus the harder it is to stop.

Since the car does the work, you have no sense of how heavy your vehicle is.

Try this. On a flat suface, have someone sit in the drivers seat and put the car in neutral, they can ride the brake to ensure nothing untoward happens. Now push the car. Its heavy, you can probably get it rolling, but you still get a sense for how heavy it is.

Now picture it hurtling along at 120 km/hr.

Impressive, yes?

It is very easy to underestimate your speed and the relative difficulty of stopping in a heavy vehicle like a car. You can know your speed exactly on the speedometer, but you underestimate how fast that speed actually is, how much momentum you have, and how hard it is to redirect or stop the vehicle in motion.

How fast is 40 km/hr? It feels slow in a car, but it is not.

So speed matters a lot. Drivers have to try to stay within speed limits, and use discretion when driving quickly around comparatively slower vehicles like bikes. Tailgating is out of the question, as stopping distances are easy to underestimate. Basically, you either pass or you maintain a respectful distance behind the bike. As a cyclist I would prefer you to pass and move along, but if you aren’t confident, just leave me space.

What about being on a bike?

Well, comparative speed is quite a bit lower, so you aren’t going as fast. Consequently you get more time to react to traffic problems, and it is easier to stop in a short distance.

The bike has some other interesting features:

1. It does not block the wind resistance, so it leaves you in a noisy environment full of traffic sounds. It is thus easier to perceive your speed.
2. Bike tires smooth out your ride, but less so than with cars, so you feel bumps and obstructions to a greater degree, and get a better sense of your speed
3. It also masks peripheral visual objects that would more accurately convey your velocity (you look forward for the most part when you ride).
4. Your available reference points (passing traffic) are moving quickly, relative to you, giving the perception that you too are moving slowly.

So cyclists have a mix of factors involved, in one way they are more aware of their environment as they are not cocooned inside a car with windows up. They feel the wind, the bumps on the road, and they hear what’s going on around them. I usually hear approaching cars before I notice them in the rear view mirror. In other ways cyclists are similarly challenged, they tend to look forward so don’t notice how fast they are going, and compared to passing traffic they appear to be moving quite slowly, when they are not.

These are perceptual limitations associated with the human senses and the human brain. We can’t do much to change them, but we can be aware of how they limit us. And here’s the thing. Cyclists have a bit of a split decision here in terms of good and bad, we feel  more of our speed but we still tend to underestimate it. So, by extension, the safest thing to do is to slow down, as we tend to underestimate our speed.

Slowing down gives you more time to react, means that when you do react you can do so in time, and reduces the forward momentum that can carry you into situations of harm.

Hold on to that thought. Slowing down might be a good idea.

Now forgive me a digression.

A respected American cycling advocate, John Forester, advocates that cyclists travel on main arteries, as main arteries get you there the fastest, and this is, according to Forester, the main concern of cycle commuters. He then proceeds to point out that many people do not choose to cycle as their commute time, compared to the car, is not good. So if faced with a choice of an hour long trip by bike and a 20 min drive by car, the bike loses. So Forester encourages cyclists to drive as fast as possible (20-25miles/hr is his target speed for urban commuting, approximately 30-40km/hr), and stick to the main routes despite the traffic. This is the only thing, according to him, that will make cycling desirable.

He does admit, that in certain cases, the congestion can be so bad that bike times are comparable to car times, but he treats this as an exception, and maintains that fast, main artery cycling is the way to go.

Well, queue my cycle commuting experience.

I have been working and living in the same places for about 10 years now. My job is about 18 km from where I live. When I first started working, I took the car. After that, it was the car and public transit. Then public transit for a while, then finally cycling, which is now my dominant transportation method.

I have tried many routes, on public transit, by car and by bike. And I have 10 years of data to go on. This has given me some fairly reliable comparative travel statistics. Let’s start with the car:

Car – Average time to/from work: 90 min round trip – 24 km an hour
Public Transit – Average time to/from work: 150 min round trip – 14 km an hour
Bike – Average time to/from work: 100 min round trip – 22 km/hr

Just for comparison, average round trip commute time in Toronto is 80 minutes. I have a long commute, so it’s not surprising I top the average time for all transport modes. I travel West and North through the city, from just North of Bloor at Christie to Jane and Steeles.

What is more interesting is the comparative data.

When Forester rejects cycling along side roads and bike paths he does so by citing speed considerations. But a look at my statistics should be illuminating.

In my car my average speed in my cross-city commute is 24 km/hr, public transit 14 km/hr, and by bike, 22 km/hr.

What this essentially means is that in Toronto, a city of long commute times and bad traffic, you are averaging around 24 kilometers an hour on a cross city trip in your car. Of course it can be less, and it can be more, but that’s the reliable average. If I can cycle at 22 km/hr, is that too slow?

So back to where we started. I have advocated for slowing down as it will increase your safety as you have more time to react to traffic situations, and you have a built in tendency to underestimate your speed.

But here is another argument, slow down as you will be competitive with the traffic, moreso for longer trips. Short hop trips can advantage the car if there are uncluttered routes, as long as traffic is not too dense the car can outrun you completely. But the longer the trip, the more likely the traffic back up, and the chance for the bike to catch up. And you tend to do better in rush hour, when the traffic is the worst, and you can pass beside cars that are bumper to bumper.

So the second argument for slowing down is that you are already doing well compared to cars if you have a long commute in a busy urban centre.

I know cyclists that would laugh at the suggestion that your average cycling speed should be around 20 km/hr. Forester targets a regular cycling speed of 30-40 km/hr. Why the discrepancy?

Two things, Forester is a touring cyclist first, he came to cycle commuting advice second, and he is pushing for touring cyclist needs. He advocates the swept down curled handlebar design to “reduce wind resistance”, and increase speed. He also advocates for the use of main arteries only, depicting bike paths as deadly spaces. They of course can be, but I suspect they would be less so if he wasn’t zipping through on them at high speeds.

I’m not going to insist that 20 miles an hour is somehow the target, it is an average by the way, so sometimes you go a lot faster, sometimes not. But the combination of bad speed perception and the reduced ability to respond to traffic problems makes for a serious safety concern. Slowing down helps with both, and in the end will not hurt your travel time as much as you think, particularly in areas were traffic is bad.

A few pics from my daily commute:

Beltline Trail, looking East. New cyclists have a tendency to want trails or bike paths for their entire commute, and that's hard to find, but there are still plenty of "short hop" trails you can use to supplement your road riding.

Caledonia Road, looking North. Caledonia is an excellent cycling road as it is one lane in both directions, with a seldom used turning lane in the middle, so cars give you plenty of space.

Lawrence Avenue, looking West. Here I am behind the traffic pack, so the road is empty.


Keele Street, looking North, and FRESHLY PAVED! So much better to ride on as the gutters are still clean and smooth.

Keele Street, looking North, at the bridge crossing the 401, thanks to the nice new "dead zone" between the exit to the highway and the right hand lane the approach to the bridge is considerably safer.

Keele Street, looking North just before Sheppard Avenue, notice that my lane is empty, and so is the left lane. The nice thing about long straight stretches like this is that the traffic quickly passes you and this can leave you with an empty road.



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