At €70 a pop, my tyres get rotated front to back, as required.
Back wears out much faster.
Wider, more supple tires might do better than that, the 26x2.2 rear on my tandem is 2k miles in, and probably has another 50% of its life left. Tandems are kind of noted for eating tires due to the loads on them.
I used to use GatorSkins - as they are perfect for London cycling. I used to commute 29 miles a day, 5 days a week, plus complete a 60ish mile ride on weekends - so times that by 47 weeks (5 weeks leave where I wasn't commuting) gives 9,635 miles. My gatorskins easily lasted a year, usually more - in fact I still have one of my London tires on my good bike, 7 years later (as the front tire) (I no longer cycle commute and only ride for leisure now.)
So I think those miles really are possible on a good tire. I used to use cheapo tires but ended up changing them 3 or 4 times a year and burning through inner-tubes.
The tandem and wider tires are not the cheap ones though, they’re Rene Hearse, roughly 90eur or so. I’d say they’re worth it, but they are about the same price as my last car tires.
So if we also assume that during the lifetime of the vehicle the cost of fuel you'll burn will be in the same ballpark as the cost of the vehicle, then the total cost of riding the bike will only be around 50% of using a car.
Normally, one assume about 24% efficiency in human pedaling, so that 1kJ of energy going forward = 1 kcal consumed.
Now, fuel cost is anyways a small part of owning a car. My 1k bike + food has lasted me years, while that's less than a newer car loses in value each month.
600kcal is ~200g of bread + 20g of butter. Bread costs about 5€/kg, butter costs 2€ / 250g so 600kcal is roughly 1,25€.
My car uses about 6l gasoline per 100km, current price is ~1,60€ per liter, so 20km need 1,90€ of gasoline.
So if I just eat cheap food riding a bike is cheaper.
If I eat at McDonalds, then 600kcal is a hamburger with medium fries, which costs ~4,50€. Then taking the car is cheaper.
This is quite surprising!
The results looks absurd because the math is ignoring a lot of real-world considerations.
Healthcare burden, I'm not so sure. Even with the massive difference in usage, street car tracks in Seattle cause a lot more healthcare burden to bikers (and pedestrians) than car drivers. There's certainly a benefit from exercise, but bicycling also has more exposure to injury during use, and not all of them are superficial injuries. Add in things like poor form inducing nerve injuries and it looks even worse.
So it's not even comparable. It's probably multiple orders of magnitude better on a societal level to be biking. Even better if we got rid of the cars causing the cyclists to be killed.
All sorts of terrain issues that are minor for a car are dangerous for a bicycle, especially at higher speeds. Where I live, it's very hilly, so it's hard to go anywhere on a bike without hitting speeds of at least 25 mph at some point on the journey. Mechanical issues, unexpected objects in the road, or errors in piloting at that speed will result in an injury for sure.
[1] https://injuryfacts.nsc.org/home-and-community/safety-topics...
[2] https://www.nhtsa.gov/press-releases/2020-traffic-crash-data...
So I think the fatality rate per trip is probably about the same for bike vs car/etc; but the rate per mile for bikes is significantly higher. It'd be interesting to look at comparable rates from say the Netherlands or another country where bicycling is better positioned.
[1] https://nhts.ornl.gov/person-trips [2] https://nhts.ornl.gov/person-miles
Edit: Source: https://assets.publishing.service.gov.uk/government/uploads/...
It is a more complex equation than that..
Probably the hardest variable to quantify is the risk of injury/death.
While I agree it could be better if everyone used bikes, but in the current reality if I choose to ride my bycicle, I'm going to share the road with 2000Kg metal boxes which are sometimes driven by distracted drivers, and I'm not willing to take that risk.
So even if I combine all the costs associated with both options, and bikes are cheaper objectively, it will still be more expensive for me.
I have an older garmin that has told me I have burned 9000 calories in a weekend, and uh, I didn’t. No evidence for that, but I simply don’t believe it. Bicycle tourists would have to have wild food intake to sustain that for weeks.
It depends a lot on the bike and on the route. On a road bike going down a straight, flat road wearing lycra 20km/h is zero effort. On a city bike loaded with groceries going through urban environment with a bunch of traffic lights 20km/h average is quite an effort.
But I think there's some factors at play here. One is that if I didn't commute to work, I would have to work out some other way to get my daily movement in. So it's not necessarily that I eat more just to bike. I just use that energy to move myself to work instead of on a treadmill going no where.
Another interesting factor is what about electrical bikes? The amount of kWh needed to move a small person vs multiple tonnes of car should make it a huge win.
Let's say you start with brand new tires on both wheels. Let's further suppose that you completely wear out your rear tire in 1 year and your front tire in 4 years. If on the first anniversary you rotate and place the new tire in front, you'll need to repeat the procedure after 9 months, and then every 9 months after that. On the 4th anniversary you'll have bought 5 tires: on the 12th, 21st, 30th, 39th, and 48th months. If you simply replace each tire as it wears out without any rotation, on the 4th year you'll have bought 5 tires, 1 to replace the front tire once and 4 to replace the rear tire 4 times.