The Quadricycle Build Story12th April 2010
A question I recieved over on the cyclechat thread dedicated to the quad build:
"is that all from alumimuim? what grade is it? And you are bolting/riveting it together?
Are you an engineer so have analysed your design or kinda building on a gut feel for what will be strong eough? (I have no idea whetehr what you are building will keep in one piece or not do you?).
Incidentally, did you not consider using 2 bike frames mounted side by side?"My response and the next picture set:
Pretty much all of it is aluminium, the bolts and what I suppose you could call the front wheel kingpins are steel. It is all bolted together, as I did not think pop riveting would be suitable, and as I mentioned in a previous post, I am not confident with Ali welding.
I'm not an engineer (I'm a theatre technician!), but a lot of my work involves carpentry, and calculating/guesstimating static and dynamic loads.
Although I have CADed up the majority of the design, it is changing as I go along, I am erring on the side of caution and over engineering most bits. For example, the choice for the main chassis tubing was 3"x1" 10SWG, 3"x1" 16SWG or 2"x1" 10SWG. I decided to go for the 3"x1" 10SWG, but am now of the opinion that the 16SWG, or the 2"x1" would probably have done the job.
At the moment, I am confident that the chassis is overly strong, and the main possible point of failure is the cheap MTB wheels I have scavenged from a pair of donor bikes. (Which somebody on here did warn me about!)
In other words, everything I'm building should stay in one piece, but the wheels might collapse, at which point I will go and buy some better ones!
I very briefly though about the two bike frames side by side during the course of my reasearch, but then dismissed the idea, as it would end up looking like a dodgy something-or-other that I cobbled together. (No offence intended to anyone who does this, it's just not my style!)
I hope that answers some of your questions, on with the photos from the last two days!
1. Working out the length of the threaded rod 'kingpin':
2. Look! A Trike!
3.How the kingpin works, and how the front wheels are attached on:
4. A view from the rear with the nearside front wheel attached:
5. A Quad! (Not sure about the cycle bit yet though!)
6. A view from the rear of with all four wheels attached:
7. Pilot's eye view- and it didn't collapse when the stoker sat down either!
8. A closeup view of how the front wheels attach on:
9. A shot of where the steering tie rod will attach.
Thats all for now. The next jobs on my list (in order of priority) are:
Seats (as I can't work out ergonomic positions for steering/pedals until these are made)
Steering
Drive/Braking
Lighting
