Wednesday, April 16, 2014

PamStroller - (How to conquer stairs)

It's very hard to imagine having a kid without having a stroller. One of the big complaints I have is having to move the stroller up and down the stairs. There's a big trade-off between having a huge SUV-like stroller with big wheels, and having a lightweight city/umbrella strollers with small wheels. In both cases, it is difficult to move up and down the stairs-- big strollers may have bigger wheels to climb stairs but are much heavier (20-30 lbs), while smaller strollers (8-20 pounds) have small wheels that are difficult to clear the stairs.

Last summer (2013) I started googling for strollers that can climb stairs more easily, but none of them are consumer ready and in production. So instead of waiting for one to come out, I decided to make one. After doing some research, tri-wheel base seems the most ideal configuration because of form factor, simplicity, and weight. Below illustrates how tri-wheel works:

The left most picture shows that intermittent but great amounts of effort is needed to either pull-up or move-down a stroller. The middle pictures shows that a super large wheel could gently spread the amount of effort needed (even though technically, the amount of "work" is the same), at the cost of weight and form factor. The last picture shows that with a tri-wheel, the amount of effort is similar to a huge wheel without as much compromise on weight and flexibility.

Here's a video of the prototype I made in action. I call it PamStroller:

PamStroller was prototyped by modifying the Chicco Lightweight Stroller. I also bought 2 extra wheel base from stroller parts store, and lastly the "Cosmos ® Pair of Replacement Stair Climbing Shopping Cart Wheels." Below are some pictures while making the prototype:
This is v1, mounted directly on the aluminum bar. It didn't work too well. The v2 version as shown on the video mounts to the plastic wheel mount, which allow me to easily exchange wheels (Chicco's original design to snap on/off wheels).

This is the original Cosmos wheels. First you take out the chrome pins.

Then, drill a whole in the center.

Add your own screws (about 4", I got these from Home Depot)

This is the extra wheel I bought, as I was about to destroy the permanent spoke, remove the rubber wheels, and replace it with Cosmos wheels.
It was a pretty fun project and took less than half a day! Is this a stroller you'd like to use? Would you like to see this readily available in stores? Are you interested in backing PamStroller on KickStarter? Please share and comment!

Wednesday, March 26, 2014

Bike Accident with a Toddler

I just looked at my blog history and find it interesting that the majority of my blogs are written months before I leave my job (i.e. most of them are written in 2009 Q2 & 2013 Q2). By inferring from historical data, I probably shouldn't be blogging now because I enjoy my time at work. However, I'm awake at 5am -- I keep having replay images of the bike accident.


I've made a lot of mistakes in my life, but this is an unforgettable mistakes that I made because it involves my 3 year old son Calvin. Calvin and I had a bike accident this weekend. His right side of the helmet cracked and he has some road rash on his right parts of the body (road rash pictures not show). I also have road rash on my lower legs and arms, and banged my right knee pretty badly. 

As we approached an intersection there were several cars in front of us. I decided to go around by swerving to the pedestrian lane (dumb!) and somehow, the front mountain bike tire got caught (on mere 1/2 inch height clearance) and *BAM* both of our heads went down first -- I can only remember hearing the sound of our helmets hitting concrete first -- and my son screaming and crying afterwards. It was the most awful thing I had experienced to date, and I caused it.

What amazed me was that after a few minutes of crying, he he said he wanted to go play in the park.

A few thoughts:
  • Always wear your helmet! There's a saying that falling from the bike is not a question of if, but when. Always wear your helmet!
  • If you must use systems similar to the WeeRide, iBert, rear seat, or anything that raises the center of gravity for the kid, DO NOT FALL because the head distance to ground is increased drastically.
  • I can no longer vouch for WeeRide. In fact I can't imagine using any system that raises a child's height, including the frontal iBert-style seats. BIG DISLIKE. I am switching to a trailer.
  • Don't underestimate a 1/2 inch height clearance even on a mountain bike. Always ride towards uneven surface by going perpendicular to it (see the Better green arrow above).
  • I just got a Burley Bee Bike Trailer. This is one of the best on Amazon (based on ratings and weight and quality). I highly recommend it. If you click on this picture and buy it, I'll get a few bucks from it too :)