Here are all the photos from our August 17th meeting at John Baron's shop, with Alan Ball. Sorry, no time to do nice organizing.
Here's what we were looking at:
1. Can we replace the expensive, heavy gas spring with shock cord "spring".
We tried this with a few bungee cords, and it worked rather well. See the videos in the next post. We will refine the approach this week by testing with shock cord set to balance John's weight. Note that without the gas spring in the way, flanking members on the frame work better, and the frame travel is much longer. The bike goes a little higher, but gets a lot shorter, and it can also go much lower, practically touching the ground if you let it. (we may have a removable stop for that)
2. Could we get the damping and locking of the frame by using a standard bike brake hub?
Again, we think the answer is yes. The internal drum hub would go on the joint under the seat and would allow firm locking of the morphing frame, at low weight, low cost. We think this control, along with some "end of travel" bumpers, may work well with the shock cord lift system.
3. The seat bottom is from an office chair. Real seat won't be that big.
4. The automatic seat adjusting system works like a charm. I didn't even realize it was happening. It just felt right.
5. When you don't worry about weight, things really do get heavy. This test rig weighs about the same as a small refrigerator. (We knew that, but still interesting.)
6. The adjustment mechanism for the gas spring didn't work the way we want. Turns out you have to adjust TWO attach points, not just one. This is because by changing only one point, you adjust travel AND pre-load at the same time, and they tend to cancel each other out. The shock cord lift system is actually much easier to adjust.
7. As designed, the bike has a huge moment arm where the axle meets the morphing frame. If you ever hit one wheel and not the other, you'll twist the frame and it will be easy to make it go out of alignment.
8. We discussed separating the rear flanking members to be closer to the wheel. This will triangulate the rear frame and will eliminate the moment arm. It will also let us use smaller tubes and save weight. Some of the sketches are related to this.
9. John has a detailed spreadsheet that shows the calculations to maintain weightlessness at every angle of the frame, and for any rider weight.. (we should post it later)
10. The pictures of Bill (in purple) on the test rig are meant to be a sequence, but they may be out of order in this post.
11. Alan is going to make some very rough concepts for review next week when Rory returns.
12. John is going to work on the shock cord lift system.
13. The items we talked about could make the morph lighter, stronger, cheaper, more reliable, easier to adjust and easier to build.