Cyclists pollute more than cars, claims Swiss economist; Scary HGV close pass video sparks cycling infra debate; Why can’t all cyclist v driver clips be like this? Cyclist hits van and apologises; Arty bike stand divides opinion + more on the live blog

Rich_cb wrote:

There are, obviously, a huge number of variables to take into account but it is interesting quite how carbon intensive exercise is. IIRC ebikes have a lower lifetime carbon footprint than regular bikes for that reason.

I think there's something to reflect on here, though I personally think it's more a fact of being aware of where our food comes from and the carbon-footprint of the food chain, rather than being a reasonable comparison of bicycle vs car.

To reach the conclusion he has, the professor had made so many hypothetical assumptions that don't exist in the real-world (assuming that all cyclists eat nothing but beef whereas drivers and passangers eat nothing, assuming that the cyclist would eat way more than they actually would for short (so, the majority of) journeys, comparing one cyclist to four passengers when most car journeys are probably single-occupancy, comparing the bicycle to a car with economy figures that are not representative of the average car, ignoring the many externalities of producing and running a car, ect).

I don't think the diet of the car drivers and passengers needs to be included.

Their diet is not fuelling their transport so can be ignored for the purpose of the comparison. Sitting at home on the sofa burns as many calories as sitting in the backseat of a car.

Cyclists will need to fuel their exertions and that fuel will have a carbon footprint.

Once you add in the manufacture of the car then the comparison is always going to benefit the cyclist but on an individual journey basis, Eg cycle somewhere or catch a lift with a friend who's going to the same place, it gets more interesting.

Rich_cb wrote:

I don't think the diet of the car drivers and passengers needs to be included. Their diet is not fuelling their transport so can be ignored for the purpose of the comparison. Sitting at home on the sofa burns as many calories as sitting in the backseat of a car. Cyclists will need to fuel their exertions and that fuel will have a carbon footprint. Once you add in the manufacture of the car then the comparison is always going to benefit the cyclist but on an individual journey basis, Eg cycle somewhere or catch a lift with a friend who's going to the same place, it gets more interesting.

If you're not going to include the maintenance calories of the car passengers, then you should also remove the maintenance calories of the cyclist.

I didn't include the maintenance calories of the cyclist.

But journeys you might go to / arrive at with a friend aren't going to be 100 km. The comparison does not reflect typical journeys of which over 60 % are 8km or less.
Also the claimed fuel economy is unrealistic.

A better measure is the marginal amount of calories to go the 8km or less.

Edit and you should be using more calories when driving as you should be using your brain !

Rich_cb wrote:

I don't think the diet of the car drivers and passengers needs to be included. Their diet is not fuelling their transport so can be ignored for the purpose of the comparison.

I think they should (or the ones for the cyclist shouldn't) up to a certain distance. I eat exactly the same breakfast/lunch if I cycle in to work or drive into work. I only eat more food than I otherwise would have done if I'm going for a long leisure ride. I'd expect that most cycle rides are short enough that no "extra" calories are consumed.

I don't think it's quite right to think of it as cyclists are always fuelling their exertions over the maintenence calroies of drivers, it's probably closer to the truth that drivers are in a calorie surplus generally and cyclists don't need to "top-up" until they hit a certain level of exertion (and it's only these "top-up" calories that should be counted).

BalladOfStruth wrote:

Rich_cb wrote:

I don't think the diet of the car drivers and passengers needs to be included. Their diet is not fuelling their transport so can be ignored for the purpose of the comparison.

I think they should (or the ones for the cyclist shouldn't) up to a certain distance. I eat exactly the same breakfast/lunch if I cycle in to work or drive into work. I only eat more food than I otherwise would have done if I'm going for a long leisure ride. I'd expect that most cycle rides are short enough that no "extra" calories are consumed.

I don't think it's quite right to think of it as cyclists are always fuelling their exertions over the maintenence calroies of drivers, it's probably closer to the truth that drivers are in a calorie surplus generally and cyclists don't need to "top-up" until they hit a certain level of exertion (and it's only these "top-up" calories that should be counted).

Am I the only one here who eats LESS when I cycle? Admittedly I'm not a 100k cyclist, more like 20-30 miles across two journeys. But the days I don't cycle I eat more.

If you're cycling then you're burning more energy than you would if you were sedentary.

You may not realise that you are eating more to compensate for that but you almost certainly are.

A long time ago I changed jobs and had to drive to work instead of cycle 6 miles each way as I had been doing. I didn't change my diet at all and within a few months was 5 kilos heavier. If you had asked me prior to the change if I ate more because of my cycling I would have said that I didn't.

To stop gaining weight I had to eat quite a bit less.

Rich_cb wrote:

If you're cycling then you're burning more energy than you would if you were sedentary.

But you're not necessarily eating more if you're cycling shorter journeys (eg commuting). We've got an obesity crisis in this country, and most people are going to be in a calorie surplus even if they're sat in a car (64% of people in the UK are overweight and 28% are obese). So you can't assume that drivers are eating exactly maintenece, and you can't assume that people who commute by bike are eating more to do so than thet would if they drove (I don't). Even if you did, a lot of people excersise and would view the commute as a workout replacement, so those additional calories would be consumed/burned anyway if they didn't commute by bike. 

Rich_cb wrote:

You may not realise that you are eating more to compensate for that but you almost certainly are.

I measure my food intake. I'm telling you, I'm literally not.

You cannae change the laws of physics.

Regardless of the length of the bike trip it will require more energy than being sedentary for the equivalent time.

That energy is derived from food.

That food has a carbon footprint.

The bike trip will therefore have a carbon footprint.

Excessive eating also has a carbon footprint. The existence of excessive eating however does not remove the carbon footprint of cycling.

I do agree with what you're saying, a bike ride does have a carbon foorprint, I just think that the food aspect has been oversimplified a little. Yes, you burn more energy cycling than sitting, that's true. But there are still other considerations:

• People don't eat exactly wha they require for the activity they're doing, some will eat more, some will eat less if they're thrying to get healthy (and there will be significant overlap between these people and people cycling to work).
• Active/healthy people excercise, and some will view their cycle commute as a replacement for some/all of this excercise. So if they didn't cycle, they'd work out and that energy would be consumed/expent anyway.
• Regular cyclists will get fitter and more effecient at using energy. So someone who's fit, and cycles to a desk job actually can burn less calories total, in a day, than someone who's unfit and drives to that same desk job.

To make the comparison in such simple terms, you have to make some non-real-world assumptions (like the professor has in his comedy scenario above).

So, you can't really count the 2500 cals I've eaten as part of the carbon foorprint of the bike ride, but totally ignore what the guy in the car next to me has eaten. It's "fuelling" his drive too - if he'd eaten nothing, he might pass out at the wheel. He also might have eaten more than me, even if he hadn't he might have eaten imported meat, whilst I've eaten vegetables I've grown myself, so the carbon footprint of his food is way higher. This is why you either have to remove the food from the discusion and make that it's own comparison, or include it for the driver (along with all of the other, significant externalities of driving).

What you'd probably be better off doing would be comparing a bunch of average cycle commuters' daily diet with the diet of a bunch of average car commuters who travel about the same distance. If you consider that most people in the UK (64%) are overweight or obese, you'll probably find that the average cycle commuter (just by a function of being a littel fitter) will probably eat less food, and not produce emissions from their vehicle (as well as not requiring the mining/refining of fossil fuels, having a vehicle that's way less damaging to produce). If you're going to make this comparison, you have to do it in a real-world way.

So yes, a bicycle ride will have a carbon footprint, but I don't it would ever be the case that it would be (as you suggested in your first post) more enviromentally friendly to take a car over a bicycle.

BalladOfStruth wrote:

I do agree with what you're saying, a bike ride does have a carbon foorprint, I just think that the food aspect has been oversimplified a little. Yes, you burn more energy cycling than sitting, that's true. But there are still other considerations:

• People don't eat exactly wha they require for the activity they're doing, some will eat more, some will eat less if they're thrying to get healthy (and there will be significant overlap between these people and people cycling to work).
• Active/healthy people excercise, and some will view their cycle commute as a replacement for some/all of this excercise. So if they didn't cycle, they'd work out and that energy would be consumed/expent anyway.
• Regular cyclists will get fitter and more effecient at using energy. So someone who's fit, and cycles to a desk job actually can burn less calories total, in a day, than someone who's unfit and drives to that same desk job.

To make the comparison in such simple terms, you have to make some non-real-world assumptions (like the professor has in his comedy scenario above).

So, you can't really count the 2500 cals I've eaten as part of the carbon foorprint of the bike ride, but totally ignore what the guy in the car next to me has eaten. It's "fuelling" his drive too - if he'd eaten nothing, he might pass out at the wheel. He also might have eaten more than me, even if he hadn't he might have eaten imported meat, whilst I've eaten vegetables I've grown myself, so the carbon footprint of his food is way higher. This is why you either have to remove the food from the discusion and make that it's own comparison, or include it for the driver (along with all of the other, significant externalities of driving).

So yes, a bicycle ride will have a carbon footprint, but I don't it would ever be the case that it would be (as you suggested in your first post) more enviromentally friendly to take a car over a bicycle.

I eat less when I cycle (or do other exercise in the morning). I don't know why but I suspect because I over eat when I don't exercise. I don't know how this works, possibly because exercise helps regulate blood sugar, possibly because exercise regulates mood. But categorically, I eat less when I cycle.

It all evens out.

How does that stack up if you power yourself with roadkill (or mangelwurzels that fell of the back of the truck, as appropriate)?  What does it do to the numbers as frequency of cars decreases and you have to add in the extra riding / lights / cricket bat for harvesting your own critters - or spade for rustling veggies?

If your bike photosynthesises (or more realistically collects some of its own electric power - like this one, someone else's calculations on CO2 saved here too) how much does that help?

I do find these kind of things interesting if ultimately beside the point.  (Because most of the people - and probably all of the people in charge - are not looking at those kind of calculations to make their decisions).

But people will be eating anyway and eating excess calories judging by the number of drive throughs.

No account of running costs though - you can't just say fuel is the only factor for CO2 emissions. Then you would have to adjust for short trips and the weather in the fuel economy.

It's never going to be a precise measurement but it is, ahem, food for thought.

There's a difference between imprecise - calories used for an hour of cycling and just ignoring things as the prof has done.

BalladOfStruth wrote:

Based his consumption-per-kilometre figures on what a cyclist would eat to fuel a long endurance ride and applied this to shorter rides where most cyclists wouldn’t eat anything extra (I never used to eat extra calories to fuel my commutes, despite his numbers assuming I’d need 200g of beef per day).

​

Exactly this, I consume exactly the same diet on the days I'm commuting a 50 km round-trip as on the days I'm not (if I'm not riding at all). The only time I take on extra calories for riding is if I know I'm going long or planning to go hard, and even then, even for a 100 miler, they amount to maybe a larger bowl of porridge and an extra banana with breakfast and a couple of flapjacks and protein bars en route.

It's also absolutely ludicrous that he is measuring CO2 output by theoretical beef consumption as well, chicken has a carbon footprint 10 times lower than that of beef, and tofu 20 times lower, it's about as valid as calculating the average motorist's CO2 output by assuming that every motorist drives a Humvee.

The other glaring omissions in the professor's ramblings is he totally ignores physiological effects of exercise.  It is no surprise that those doing regular aerobic exercise (ie sucking in more oxygen and burning more calories) tend to be lower weight. Also, depending upon the level of activity (in my case climbing cols several times per week), we have a physiology adapted to make more efficient use of energy. So in simple terms, while we may use more energy while exercising, we use considerably less when going about our daily business, because we are carrying less weight, and doing so more efficiently. If you don't believe me, walk up a couple of flights of stairs alongside a sedentary person, and see who is sucking in more oxygen at the top! 

I remember reading a similar story once upon a time, and usually the Big Media Company will just go ahead and use the art/video/whatever anyway, even without permission.  If caught out, they just apologise for any confusion and take it down.

its started...

No point in having nmotd unless we all reflect on what we could have done better. Hazard perception, risk assessement are all part of road craft regardless of your second, valid para.

As Muncrundle said before "if you are moving, there is almost certainly something you could have done to mitigate the risk. If you are stationary, there might have been something you could have done."

Is it not fair to do both if the situation warrants it? Every commenter here has acknowledged that the root cause of the problem is that the infrastructure is not sufficient, and that the HGV driver has driven into a compulsory cycle lane. But is it not also fair to say that if a clear and obvious danger has presented itself, it's perhaps best to back off?

The above video highlights the need for properly segregated infrastructure, but it also highlights the value of a little hazard perception. 

It doesn't miss the point at all. No-one is arguing the infrastructure isnt crap or that the lorry was competently driven but the cyclist displays little or no situational awareness. Cycling into obvious hazards will end up getting them seriously hurt or worse. The lorry encroaches on the cycle lane several times in that video. The first time was enough for me to be saying "he hasn't got the foggiest where his arse end is, time to back off and keep him in front where he poses no danger to me" and yet after that the cyclist goes back into danger by moving alongside, then gets far too close to the moving lorry rather than let the van out. Yes the van should not have been there but it was so resolve the situation safely not put yourself in more danger. Then, still not having reacted to the hazard, he almost gets trapped when the lorry encroaches again and still decides not to back off but to push on through and get into the blind-spot. To put this one bluntly, that was the cycling equivalent of putting your head in the lion's mouth, after it has already snapped and snarled at you a few times.

If the situation were reversed, would your opinion be the same? If the HGV came alongside a cyclist (and is therefore traveling faster than the cyclist) in a separate lane, and the cyclist wandered into the HGV's lane, do you think the HGV should hold back after the cyclist got back into its own lane? I wouldn't begrudge the HGV from continuing to pass the slower road user in a separate lane, and if the cyclist veered into the other lane again, it would be the cyclist at fault.

If passing other road users in separate lanes is considered an "obvious hazard", why do we do it on a daily basis? Why do we have multi lane carriageways at all? Why do we have cycle lanes? Or pavements for that matter (noting that the pavement is part of the highway after all).

Read my post again. At no point did I say that generically no cyclist should pass an HGV on the inside when in a cycle lane.

Risk assessment and hazard perception are simple concepts. If you spot an obvious hazards (in this case the HGV encroaching into the cycle lane in the first few seconds of the video) with potential consequences that you can't justify (in this case getting crushed by a 44 tonne artic) then look for a control measure that you can immediately put in place to reduce that risk. You can't immediately change the infrastructure to one that properly segregates, you can't immediately make the HGV driver aware of his surroundings or prevent the lorry from encroaching, the only thing you can do is position yourself in such a way to control as to remove yourself from the danger. The cyclist in this clip did not attempt to do that, rather he immediately re-entered what had already been clearly shown to be a danger zone without anything changing to make it safer. In fact the only apparent change, the van partially blocking his path, made the situation more dangerous and yet he ploughed on. Sorry but that is atrocious hazard perception.

To answer your question, if I were driving a car or HGV alongside a cycle lane and a cyclist in front veered into the vehicle lanes, then that would affect my calculation on when it was safe to pass knowing what I then knew - that this cyclist was perhaps not the most stable for whatever reason. In the real world, you can't rely on everyone around you to keep you safe, you need to play a part in keeping yourself safe. If the cyclist veered into the vehicle lane again would it be their fault? Not in the way you are meaning. I would be distraught if I hit a cyclist who had not seconds before demonstrated that they did the unexpected and I just ploughed on into them regardless as that would also demonstrate immensely poor hazard perception.

LeadenSkies wrote:

that would affect my calculation

But you would still pass them. Of course you would. It's not a criticism at all - I would too.

I find it interesting how as a society we place greater responsibility for preventing harm on those who are at greater risk of being harmed; and not those who are at greater risk of causing harm. We (myself included) wouldn't expect the HGV to back off and stay behind a slower-moving cyclist, but we do expect a cyclist to back off and stay behind a slower-moving HGV.