# Weird happenings in spacetime

#### Matthames

##### Über Member
On my commute there is something weird that happens. I cycle the exact same distance going there and coming back, yet the journey home is 1/10th of a mile longer

What is going on? Although there is a possible explanation in that I have to negotiate a couple of roundabouts, however it is difficult to actually see that it would add that much of a difference.

#### GrasB

##### Veteran
if you actually think about it around 150 meters isn't that far & you'll be surprised how much of a difference being on the inside & outside of a long sweeping bend will make.

#### marinyork

##### Resting in suspended Animation
All probably within the accuracy that you can measure it (externally to the odometer).

#### Dayvo

##### just passin' through
You're on the other side of the road, so if you ride on a curvy, crescent-shaped road, your distance will differ!

Maybe!

#### robz400

##### Well-Known Member
I have the eact same thing, to work is 9.52 miles and home is 9.64?

#### GrasB

##### Veteran
Dayvo said:
You're on the other side of the road, so if you ride on a curvy, crescent-shaped road, your distance will differ!
Very true, the difference between using the offside rather than the nearside lane (ie flowing in the traffic as the road is marked rather than keeping to the nearside) for about 3/4 of a mile results in around 0.1 mile difference in the journey distance. Then the difference between taking a free line over the flyover or keeping to secondary, when there are cars about, is another 0.05 miles.

#### Globalti

##### Legendary Member
Are you riding west-east going home?

That's the reason.

#### Arch

##### Married to Night Train
Matthames said:
I cycle the exact same distance going there and coming back, yet the journey home is 1/10th of a mile longer

Doesn't the second half of that sentence automatically deny the first half?

Like others said, it's down to being on the inside/outside of bends and so on. Not wierd at all. After all, anything more than a 100m race in athletics, they take the bend of the track into account with the starting positions.

#### Davidc

##### Guru
It's global warming - the earth's expanded while you've been at work!

#### ColinJ

##### Puzzle game procrastinator!
Arch said:
Like others said, it's down to being on the inside/outside of bends and so on. Not wierd at all. After all, anything more than a 100m race in athletics, they take the bend of the track into account with the starting positions.
I used to think that it wouldn't make that much difference but then I did the calculations.

A 400 metre athletics track effectively consists of a big circle with four 90 degree arcs separated by 2 long straights and 2 short straights (which could be of zero length). The straights are the same length no matter what lane you are in. Athletics track lanes are 1.22 metres in width so if r is the radius of your lane then the radius of the next one out is (r + 1.22). That means that the second lane is 2 * pi * 1.22 metres longer than the inside lane or 7.67 metres - near enough 2% longer. That's quite a difference!

A 200 metre race is run in lanes and so is a 400 but the 200 only goes round 1 bend so the lane stagger would have to be 3.83 metres for a 200 metre event and 7.67 metres for a 400 metre event.

#### dondare

##### Über Member
This is a logic problem.
The explanation is that the calibration of your measuring-device changes between morning and evening. It depends on the circumference of the wheel with the sensor, which can change with tyre pressure.
So logic dictates that you must have a slow puncture.

#### Sheffield_Tiger

##### Guru
I wouldn't mind some weird happenings in spacetime...

..if it meant that Amy Pond paid me a visit