The Quadricycle Build Story27th July 2010
Here are the latest updates & photos!
Bottom Bracket Initial Design (friction hold in within the frame)
The amended design, as implemented on the stoker's side, uses a wider hole and a slightly larger gauge of aluminium tubing to help provide space to bolt it in place. Photos to follow. I think, once the quad is in a fit shape to ride a few miles, I'll pop along to a local welding shop and get them to weld the BB's into place in the rectangular tubing, as this is the one area of the quad where I am struggling to get things nice and snug and immovable.
The Seats
Currently each seat is made up of a welded steel right angle frame (salvaged from a piece of scenery that was being chucked at work) with a couple of sheets of 18mm ply attached and some thick foam to save a sore bum. In their current guise, these seats probably add about 5-10Kg each onto the weight of the bike, so I'm looking for ideas to reduce this. Probably in the form of proper recumbent bike seats!
Gears
I have gone for the axel-mounted style rear derailleurs, quite simply because it's really obvious where they need to go, although because of the angle they sit at, removal of the derailleur(s) is required to take the rear wheel(s) off. Pictured here (pilot side) prior to the chain being run through. I haven't got as far as front derailleurs yet, mainly because of the slight movement that still exists in the BB's. Since I took this photo, I've actually drilled out a bit more so that the rear wheels sit higher up in the metal now, to help with the chain path, so to fit the derailleur on, I've had to angle grind off the tip of the curvy section at the top of it.
Steering
Pictured below is an experiment which took place whilst trying to work out the steering linkage, from the shaft to the wheels. I'll follow up in the next few days with how the final linkage looks.
Because of how the steering column aligns almost exactly with the front right wheel, I couldn't use the same design found on a number of other quadricycle models I have come across in my research. It took a bit of thinking outside the box, and a bit of good old Technic Lego to come up with the final design.
And here's another picture of the steering column prior to handlerbars being fitted:
Brakes
No Photos as of yet, but rear brakes have been fitted to both rear wheels. I intend to get hold of some dual-pull brake levers so that both rear brakes can be operated on one lever, and both front brakes on another lever.
Testing
Well I'd been waiting for this moment for a long time- I finally got a second set of brakes fitted once I found out that the LBS round the corner from me stocked 3m brake cables, and I set out across the road to Morisson's car park (after closing time, so it was deserted).
This is the most compehensive testing so far, everything else has just been out of the garage and up and down my small driveway.
It Works!!!!
Is that the recumbent smile I've read so much about?!
My tests today have shown that I seem to have got the Ackermann geometry pretty much spot on (well, at least, when I realised yesterday that I was reading Peter Eland's spreadsheets upside down it is now spot on and the quad's turning circle is about 5m2 for a full 360 (although this should only be attempted at low speeds as I found out when I nearly tipped myself!)
The second attempt to get into the car park (On the first, the chain came off the front chain ring due to BB movement so I had to take a quick left turn off the round about!):
Now I was having so much fun I got a bit carried away, and on returning home, forgot I was still on a test ride, and took the turn into my driveway a little on the fast and sharp side, and managed to bend the rear wheel out of shape. And so, the hunt began for some stronger wheels!
