On Friday, I took a gamble and went on a Pedalpalooza ride that left the route up to chance. As luck would have it, myself and the 20 or so others on the ride got lucky and had a memorable excursion through the streets of Portland.
The ride was called “Get Lost” and was led by the Deacon of bike fun, Amos Hunter. Amos brought two big dice and the rules were simple. We roll to see where we go — an even roll means we go right as many blocks as the number on the dice, an odd roll and we go left.
Intrepid riders conquered stairs…
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and major arterials.
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Our group was a neat mix of people; old, young, male, female, a parakeet. Our first roll took us south from inner SE Portland (Belmont and 9th). We then headed west over the Hawthorne Bridge (which we counted as two blocks) and into downtown. We stopped at the park blocks between SW 3rd and 4th to roll again. 7 blocks south was our command, which took us past Keller Fountain and up the stairs and onto the SW Pedestrian Trail adjacent to Pettygrove City Park. Staying true to our rolls, we ventured east toward Naito Parkway through a parking garage and another set of stairs. From there, we headed south on Naito, eventually riding right through the Barbur tunnel.
After grinding up a few hills and getting a bit boxed-in between 99W and the South Waterfront (with the Aerial Tram overhead), our dice rolls pointed us back east over the Willamette River. As luck would have it, our route would have to be the Ross Island Bridge, which is a four-lane thoroughfare with no shoulder. And it was rush-hour. Thankfully there were enough of us to easily take the lane and we rolled across without incident.
can be downright pleasant in a large group.
Back on the east side, we crossed SE Powell/Hwy 26 using the non-motorized overcrossing and then somehow, miraculously, we pointed our steeds right back to Sparky’s Pizza on Belmont right where we started from. What are the chances?! We pondered that question with pizza and beer.
View my photo gallery of this ride here. For more great rides like this, check out the Pedalpalooza calendar.
… right back to Sparky’s Pizza on Belmont right where we started from. What are the chances?!
Ya rolled a natural 20!
WOOT!
Hope I’m not working next year, this sounded like too much fun.
Nice story. Rush hour on the Ross Island… wow. I need to find a way to turn this into a biking/drinking game. I’ll be rich!
There are two key theorems about 2-dimensional simple random walk, otherwise known as the Drunkard’s Walk:
1) The probability of returning to the starting location is 1. (That is, you will return to your starting location with certainty.)
2) The expected time to return to the starting location is infinite.
(The rules you used for creating your path are not those of simple random walk, but I have a feeling the theorems are still true. Mathematical analysis of your rules would be interesting.)
So it is not so much amazing that you returned to your starting location, but that you got back so quickly.
By the way, I used to lead an annual Random Bike Ride when I lived in Madison WI. We’d go out into the cornfields and roll dice and flip coins to create our route. The adventure of going out on a ride where you truly have no idea where you are going makes the trip way more fun.
I salute those who bravely ventured out into the stochastic routes of Portland.
odds are dice turn up even as many times as odd (unless your in vegas)…
glad no one rolled a natural 1 XD
I super bummed I had to work now! I really wanted to go on this ride! Next year, I’m taking the full two + weeks off from work to enjoy as much Pedalpalooza fun as I can!
This continues to blow my mind. When we rolled into that parking lot and I looked over and saw the Sparky’s sign I could not believe it.
Thanks for coming everyone, this will definitely be a recurring Pedalpalooza event.
3-speeder
1) The probability of returning to the starting location is 1. (That is, you will return to your starting location with certainty.)
2) The expected time to return to the starting location is infinite.
The dimensionality of your path is
1 <= D <= 2 where D approaches 2 as path iteration approaches infinity.
Given that most of us don't have the attention span or endurance to stick around for infinite iterations:
What is the probability of returning to the starting point when the number of steps is finite?
That looks like a lot of fun but, coincidentally, I (by myself) made my first trip over Ross Island round rush hour yesterday. The air quality from exhaust and kicked up dust was so bad, I was trying to spit the taste out of my mouth for the next couple miles. It gave me an idea for a ride next year… involving gas masks.
q`Tzal: The dimensionality of simple random walk refers to the dimension of the grid the walk is taking place on, not the dimensionality of the path.
The theorems I cited are for a rectangular grid on an infinite plane.
I realize that the Pedalpalooza ride was on a finite sphere (the earth), not an infinite plane. It also does not take place on a regular grid, but rather on an irregular street network. Extrapolation from a mathematical ideal to physical reality is always done at the modeler’s risk.
One could try to compute combinatorily the probability of returning to the starting location at some point during the first N dice rolls (say, for N=100). Or one could do a Monte Carlo simluation based on the acutal street grid of Portland to estimate this probability. But I don’t feel this calculation would create the same aura of adventure as the theorems I mentioned.
That being said, if someone takes the time to do such a calculation or estimation, especially if done over several values of N, I’d be interested in the results.
One time I stopped to enjoy a Clif bar on that overpass while I looked at traffic coming off of the bridge. A motorcycle cop must have thought I was up to trouble, because he actually rode his motorcycle up the ramp to see what was going on. He seemed to think that I was up there tagging the thing.