....If this is true?

[hubgearfreak]

Also a car is only around 25% efficient, whereas a bicycle is much more efficient that that (anyone know how much?).

it's not the bike that's converting food into muscle movement.

i think you could use 90% as a ballpark figure for a bike's efficiency, and 25% for the rider's ability to convert colories in into leg movement

And finally efficiency falls as speed increases

you're right. so a leisurely ride at 8-10mph takes little more energy that sitting driving a car does.

everybody still seems to be ignoring that the car's driver still needs energy, or that the cyclist will use calories even when he's not travelling

[Mick F]

I'm not.

I'm well aware of calorie usage whilst just sitting down, and any calorie figures I referred to up-thread includes "normal" usage.

If I were to sit down all day and do nothing, I doubt I'd use as much as 1,000cals for 24hours.

However, if I were to go for 40miles of hilly ride, I'd use 3,000cals (perhaps) on top of my 1,000cals for sitting down and doing nothing for the rest of the day and night.

Four strenuous hours on my bike in the Cornish hills equals 3,000cals.
Four hours of doing nothing uses 150cals. ie 5%.

[aek]

Another examination of energy use of bikes and cars, including the fuel used to make food: http://www.lafn.org/~dave/trans/energy/ ... nergy.html

This article seems to exclude the fact that a person will still eat about the same amount of food even if they are driving. Who said that cycling required more food than driving?
I started cycling about a year and a half ago, but i eat about the same as before. However, i don't consume petrol anymore, the only extra cost i've got is in terms of time because i wake up 45 minutes earlier than usual, but if i would be driving and wanted to keep fit as well, the time i would need to spend at the gym would be more than 45 minutes.
Then there's the debate that you spend money on a bike and that producing a bike takes energy as well, but how does that compare to the energy required to produce a car ? How about the environmental impact ?

If you just take a practical case as an example, you can easily see that cycling is more efficient in every way.

[meic]

Something a lot of people who bash on about vegetarianism and veganism don't realise is that foods like tofu actually take more energy to produce than good old British beef, which requires the most energy out of all of our usual meats.

After the beans have been grown (usually in the far East), processed, compacted and shipped over here you're much better off just buying British meat. Highly nutritious but most importantly, tasty.

There could be a reason why I dont realise.

Funnily enough, most of the soya beans coming into this country (I thought mostly from South America) are destined to be food for British cattle, rather than tofu.

Vegetarians dont exist off a diet of tofu, my family has just 200g* in one meal in the week.
We could eat the same beans that presently go to feed the cattle
Doesnt your British beef get processed before it is eaten too?


*Made and packed by R&R Tofu Ltd. Malton. North Yorks. (which isnt normally thought of as part of Asia )

[hubgearfreak]

I doubt I'd use as much as 1,000cals for 24hours..

you can double that for an average person. people use up power at the rate of a lightbulb...between 60 and 100watts. 1000Kcalories a day is 48 watts. i'm not calling you fat, but you're not 7 stone, ie. a small person that may be below 60w.

working off O2 consumption for 10 minutes, i'd take 3500Kc for 24hrs.

unless of course you are dim

[Mick F]

Recommended intake for men is 2,440cals.

This means "normal" men with a normal lifestyle.

Sit down all day, or stay in bed all day, and the only intake you need is to keep warm. I doubt sitting still for 24 hours would consume as much as 1,000cals.

[kwackers]

Recommended intake for men is 2,440cals.

This means "normal" men with a normal lifestyle.

Sit down all day, or stay in bed all day, and the only intake you need is to keep warm. I doubt sitting still for 24 hours would consume as much as 1,000cals.

Some of us also need to run our brains...

[hubgearfreak]

I doubt sitting still for 24 hours would consume as much as 1,000cals.

you may doubt it mick, but it doesn't make it so. have you tried googling it?

add - i've found a calorie calculator. you can enter non-existant as your activity level if you wish.

http://www.weight-loss-center.net/daily ... lator.html

[horizon]

I'm just pondering here that we are looking at miles per calories and not calories per hour. The theories on travel tell us that journeys are not related to distance but to time: an hour spent travelling by bicycle will produce exactly the same result as a car travelling on a motorway for an hour - we will simply have altered the location of our desired object (work, relatives, shops etc). In that sense a bicycle is hugely more efficient than a car in that our first decision on riding a bicycle is to reduce our travel horizons to take into account the lower speed. It is the myth of mobility that gives rise to excessive car use; once that myth is challenged, the bicycle once again becomes absolutely more efficient.

[Mick F]

I doubt sitting still for 24 hours would consume as much as 1,000cals.

you may doubt it mick, but it doesn't make it so. have you tried googling it?

No. My statement is based on common sense.

If an normal active male needs 2440cals to function normally, it stands to reason that if he were to do absolutely nothing for 24 hours, he would need less than half of what he would need to doing an 8hr day at work, commuting, life at home and leisure time.

If you think it takes more than 1,000cals, it must mean that the 2440cals is too low.

[kwackers]

I doubt sitting still for 24 hours would consume as much as 1,000cals.

you may doubt it mick, but it doesn't make it so. have you tried googling it?

No. My statement is based on common sense.

If an normal active male needs 2440cals to function normally, it stands to reason that if he were to do absolutely nothing for 24 hours, he would need less than half of what he would need to doing an 8hr day at work, commuting, life at home and leisure time.

If you think it takes more than 1,000cals, it must mean that the 2440cals is too low.

I think your problem is 'normally active'. Normally active is sat in a chair for most of the day. If you do physical labour the 2440 is too low. I would hazard a guess that lying in bed all day will still require around 1500+.

[hubgearfreak]

No. My statement is based on common sense.

fair enough, why look up the published figures from scientists that are available when we've got gut feeling

[Malaconotus]

Really - bicycle lifetime 525 miles?
That's not an illustration of how long a bike lasts, it's an illustration that people don't use them - and calls the sanity of the author(s) into question

Those are US calculations, and they are perhaps not unreasonable. The UK figure, according to my workings which I still have to blog properly, is 900 miles. The Netherlands is 8,275 miles. That would radically change the calculations, I think.

[[XAP]Bob]

Really - bicycle lifetime 525 miles?
That's not an illustration of how long a bike lasts, it's an illustration that people don't use them - and calls the sanity of the author(s) into question

Those are US calculations, and they are perhaps not unreasonable. The UK figure, according to my workings which I still have to blog properly, is 900 miles. The Netherlands is 8,275 miles. That would radically change the calculations, I think.

They are unreasonable - they are not measuring the lifetime of a bicycle, they are measuring how much an underused cycle is used.

A cycle can easily do 10,000 miles.
I'd hazard a guess that a well maintained (not ultra light) steel frame would outlast most cyclists.
My BSO 2nd bike has done 6 or 7k without (frame) issue*, and that's hardly been used for over a year now that I'm on a 'bent.

At 600 miles the chain will need a good clean, but (almost certainly) won't need replacing, nothing else will need replacing either. To say that the lifetime of bike is equivalent to the use most bikes see is completely absurd.

I could equally declare that the lifetime of a car is 3 miles because you can drive one out of the factory gates and leave it to rust.


Bob

* I've upgraded the fork for disc brakes and replaced wheels, chains, chainrings, freewheel... Almost all routine (but reactive) maintenance really.

[gilesjuk]

Something a lot of people who bash on about vegetarianism and veganism don't realise is that foods like tofu actually take more energy to produce than good old British beef, which requires the most energy out of all of our usual meats.

After the beans have been grown (usually in the far East), processed, compacted and shipped over here you're much better off just buying British meat. Highly nutritious but most importantly, tasty.

It's not just about energy, it is about land mass and water usage. Cattle need big fields, water and food. In the same land space you could grow a lot more food.

If you eat the food instead of giving it to cows then eating the cow you get 100% of the food.

If you give food to the cow and then eat the cow there will be only 10% of the food you gave to the cow.