Cycle versus car - false economy?

wafter

Über Member
Location
Oxford
Well, clearly not as we all know that cycling's infinitely cheaper in most respects, however..

Since justifying the purchase of my Fuji for utility rides earlier in the year I've been keeping a record of the journeys I do that otherwise would have been done in the car; and how much I've saved in petrol.

So far, two months in and I'm winning to the tune of anywhere between £13 and £19 saved in fuel... heady stuff indeed!

The process did set me wondering about the actual, energy cost of cycling - when offsetting a ride against fuel we all make the assumption that the riding's free, when of course energy is expended to propel my ample frame through the air - and like everything else in our grotty, consumptive society this costs money.

My faithful Civic typically manages around 45mpg; so at £1.65 per litre this is about 16.5p/mile. According to the internetz 1 litre of petrol contains around 31 Megajoules (MJ) of energy, so at around 10 miles / litre each mile is costing me around 3.1MJ. Conversely, on the bike I seem to average around 50Kcal (or around 210KJ) per mile. So... in terms of energy efficiency, it takes about fifteen times less energy to drag my arse to the shop on the bike than it does in the car.

This leads us on to the question of how much the energy expend on the bike is costing. Apparently one 50g Mars bar - at around £0.60 street value - contains about 230kcal of energy. On paper enough to propel me around 4.5 miles at a cost of around 13p/mile.

Taking a more relevant food choice, a decent grilled noshup in the house of Wafter might consist of 2x eggs (150g, £0.50, 150kcal), 2x slices of hippie GF bread (50g, £0.50, 150kcal) and 3x fat butcher's sausages (200g, £1.50, 450kcal). That's a total of around 750kcal for £2.50 outlay, or around 300kcal /£1 / 17p/mile.

Of course none of this takes into account the intricacies of physiological efficency (for every 1 mars bar consume you might output 0.7 mars bars worth of physical effort) or other sources of error (bite me, it's been twenty years since I had to write a proper paper).

Likewise, of course it also fails to take into account the other benefits of cycling (reduced immediate pollution, maintence and sunk vehicle cost; both financial and material).. plus of course the infinitely reduced desire to jump in front of a train post-ride; from which some us benefit.

In summary, absolutely not a reason to discourage anyone from the joys of utility riding; but perhaps a sobering reminder that despite how some of us try to escape we're all caught in the hamster wheel one way or another :rolleyes:
 
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ColinJ

Puzzle game procrastinator!
In summary, absolutely not a reason to discourage anyone from the joys of utility riding, but perhaps a sobering reminder that despite how some of us try to escape, we're all caught in the hamster wheel one way or another.
Some - yes; all - no! :okay:

I don't drive and these days only get a small number of lifts a year. Nearly all of my utility journeys are done by bike or on foot. Most of the other journeys are by train or bus. I don't eat extra to fuel any of them.
 
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wafter

wafter

Über Member
Location
Oxford
Some - yes; all - no! :okay:

I don't drive and these days only get a small number of lifts a year. Nearly all of my utility journeys are done by bike or on foot. Most of the other journeys are by train or bus. I don't eat extra to fuel any of them.

Commendable certainly - and you'll have lost all of the sunk costs associated with the car - tax, MOT, servicing, insurance etc :smile:

Unless you're getting markedly lighter with each trip to the shops you must be fuelling yourself somehow, though ;)
 

ColinJ

Puzzle game procrastinator!
Unless you're getting markedly lighter with each trip to the shops you must be fuelling yourself somehow, though ;)
I didn't say that I wasn't eating - I just don't eat any extra because of utility walking/cycling trips. Longer leisure walks and rides - yes, of course!

I AM getting lighter, but wouldn't notice it after a single trip to the local Lidl or Aldi... :laugh:

I am lucky in that I am very close to those shops. In fact, I deliberately extend my shopping trips to give me more exercise.
 

tyred

Legendary Member
Location
Ireland
A warning light came on on the dashboard of my Skoda. I ended up being at four different garages and spending the best of €800 before I got the light out and a usable car again.

So far, no warning lights have ever come on the dashboard of my bicycles and apart from a broken frame, I have yet to have a fault with my bikes that I can't fix myself.

Cycling has the added benefit of keeping me fit and thin(ish).
 

Jameshow

Über Member
Your food costs seem a little high esp the bread ...


"Taking a more relevant food choice, a decent grilled noshup in the house of Wafter might consist of 2x eggs (150g, £0.50, 150kcal), 2x slices of hippie GF bread (50g, £0.50, 150kcal) and 3x fat butcher's sausages (200g, £1.50, 450kcal). That's a total of around 750kcal for £2.50 outlay, or around 300kcal /£1 / 17p/mile."
 
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wafter

wafter

Über Member
Location
Oxford
Your assumption is that those who cycle instead of drive eat more than those who drive. But I don’t think that is proven.

I didn't say that I wasn't eating - I just don't eat any extra because of utility walking/cycling trips. Longer leisure walks and rides - yes, of course!

I AM getting lighter, but wouldn't notice it after a single trip to the local Lidl or Aldi... :laugh:

I am lucky in that I am very close to those shops. In fact, I deliberately extend my shopping trips to give me more exercise.

Well, assuming one's energy intake is balanced with their expenditure under normal circumstances, any additional energy outlay is either going to result in weight loss or increased energy intake to maintain a constant mass. That's just how it is..

The effects might be more pronounced for me mind, as the butcher's a 25 mile trip away, the supermarket 20 miles.. the least of which is around 2/3rds of a typical calorific intake so it's bound to be noticed!


Your food costs seem a little high esp the bread ...


"Taking a more relevant food choice, a decent grilled noshup in the house of Wafter might consist of 2x eggs (150g, £0.50, 150kcal), 2x slices of hippie GF bread (50g, £0.50, 150kcal) and 3x fat butcher's sausages (200g, £1.50, 450kcal). That's a total of around 750kcal for £2.50 outlay, or around 300kcal /£1 / 17p/mile."
Yeah, that's what I get for buying higher-end gluten-free stuff. Significantly more expensive than / not as nice as a quality sourdough, but then it doesn't make me utterly hopeless either - so there is that :laugh:
 

Ming the Merciless

There is no mercy
Location
Inside my skull
Well, assuming one's energy intake is balanced with their expenditure under normal circumstances, any additional energy outlay is either going to result in weight loss or increased energy intake to maintain a constant mass. That's just how it is..

Which will establish another equilibrium if they lose weight. Otherwise they were putting on weight when driving because they weren’t in equilibrium and cycling brought it into balance. The lighter you are the lower your basal metabolic rate. Thus the lighter you are the less you may eat even with the cycling.

Your assumption is that someone who replaces car trips with cycling is eating more. But the opposite is just as likely due to their lighter weight and compensatory mechanisms which means their overall energy expenditure over a day or longer is not higher but can be lower. Fat is not biologically inert.
 
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This reminds me of a review I saw in an old Car magazine many years ago

Peugeot had recently started selling a 10 speed drop handle bar bike at a very reasonable price (steel frame)
wonderful things - but I'm biased because it was my first proper bike and I loved it
it was somewhere around the early 1970s

Anyway the Car mag decided to do a comparative review of the bike against a cheap car - can;t rember what car they chose but it was all for comedy purposes anyway

They measure fuel consumption in pints of Double Diamond
and included the number of pints it required to get the researcher to agree to do the test

pre digital days (as you can tell by the dates) so no chance of finding it online
 

ColinJ

Puzzle game procrastinator!
The effects might be more pronounced for me mind, as the butcher's a 25 mile trip away, the supermarket 20 miles.. the least of which is around 2/3rds of a typical calorific intake so it's bound to be noticed!
Those would be 'proper' rides! :okay:

I lengthen my shopping trips to 7-10 kms and include 125-150 metres of ascent just to justify getting the bike out and carrying the lock.
 
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wafter

wafter

Über Member
Location
Oxford
Which will establish another equilibrium if they lose weight. Otherwise they were putting on weight when driving because they weren’t in equilibrium and cycling brought it into balance. The lighter you are the lower your basal metabolic rate. Thus the lighter you are the less you may eat even with the cycling.

Your assumption is that someone who replaces car trips with cycling is eating more. But the opposite is just as likely due to their lighter weight and compensatory mechanisms which means their overall energy expenditure over a day or longer is not higher.

A valid point to a point, however your BMR has lower limits and your energy has to come from somewhere..
 

Sharky

Guru
Location
Kent
When I first started commuting into London, I tried to avoid buying a season ticket. So when I was running late, I drove in instead. Yes you could drive in, in those days and park for a modest charge in "bombsite carparks". So I didn't really save any money.
In the end, I just renewed my yearly season ticket and cycled in on the days I wanted to.

So the London commutes didn't save any money. Later commutes outside of London did save the alternative cost of the petrol money, but this had to be offset against an increased appetite.

But for me, cycling has never been about cost savings.
 
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