Hello, Paul!
Thank you for your opinions and suggestions!
I will consider them seriously and compared what I have on disposal (now reserve) and that I could construct! Of course, safety on the first place!
Why I insisted on four wheels:
- Easier to calculate and secure stability and in practice?
Stability is mainly 2 things :-
1) height of centre of gravity above the ground
2) track width of rear wheels
A quad turns the usual stability triangle into a rectangle however remember the delta I raced in at the WC2024 ? that has a 18" rear track and a 8" seat height ! not a single person said your rear wheels were to close together !
- In total, four wheels are stronger than three wheels of the same
The AZ forum considers wheels to be stronger either by being
a) smaller diameter i.e 20" instead of 26" [ and above ]
or
b) having more spokes i.e some of the BMX wheels have 36 , 40 or 48 spokes were as 26" wheels [ front ] may only have 32 ?
- kind and size? In my project, the fourth (second rear 26" wheel) would add just a little more than the weight of the wheel alone;
- I am not sure that just one standard bicycle's 20" wheel is strong enough to accept side-forces - axial pressure on axle, bearings, hub, spokes and rims? It could be used at front or at rear, because I had both of them from teenagers MTB. Therefore, theoretically it is possible to construct tadpole or delta configuration. At front, it would give me precise steering, suspension and brake! At rear it would give 7-speed transmission. But for how long in any of the cases? Could entire complete components of front part good enough to stand alone? Therefore, I planed to have two 20" wheels at front, with suspension and brakes. I could use modified front forks from old quad or mage my own steering complete - have some ideas. Wheels supported on both sides
All my Python trikes have 20" [ racer had 16" at rear ] wheels and do up to 1500 km a year , some have been [ like yours ] beat up BMX wheels that have already had a life and some have been lucky buys from shops however not a single on has either failed in service nor I think [ memory not as good now ] broke a spoke
- Then, standard bicycle's 26" wheel could be even weaker than 20" wheel? So, two of 26" wheels on closer or wider trail would have stronger resistance toward twisting and even braking? Even, I was thinking on adding a pair of 26" wheels from old quadricycle as reinforcement (got some ideas to connect each pair), but that should be over-thinking and over-loading of project. One 26" wheel will use 3-speed internal transmission and contra-brake/coaster/brake... The another 26" wheel will use drum-brake, that could be used as parking brake, too... …
Obviously I appear to be trying to drive you away from a standard Mochet style quad and i must stop that. You have your heart set on owning/driving one [ you become a driver and not a rider as you are inside it and NOT straddling it [ like a bicycle ]]
For sure, the weight could quickly grow. As I remember, each of my bicycles weight 12.5 kgs, so two of them = 25 kgs and quadricycle = 52 kgs ~ 114.5 pounds! All added construction = 27 kgs ~ 59.5 pounds; That is just new metal - because transmission, steering and suspension was already on bicycles. Only new was crank-pedals, but original 4 pedals were removed!
This time I couldn't consider new special wheels for quadricycle or tricycle, they should cost around 1.000 Swiss franks here in Bern when/if founded... Then disk-brakes, then special suspension/support and so on. Especially commercially made single-side supported wheels are expensive, proper forks, too... However, I was thinking about modification of 20" wheels, to be stronger and simpler! I do not know what is inside diameter of hub (removed bearings and axle)? In old Zombie Forum I found solution: instal/fixed one axle (15mm-20mm, or whatever between) with longer part outside hub, with two proper bearings on that part. Not so elegant solution but practical. Only, steering system should be modified a little... If I use front forks form old quadricycle, I could turned them for 90° and fixed such axle - there would be a lot of space inside system for extension of axle and bearings ? If I make own steering system, such axle and its bearings would be inserted in wooden block or metal frame with turning points above and bellow, like false king-pin...
--- ---
Did you find this thread ?
Delta design thread
I started off wanting to design a delta trike , someone suggested I could almost get the same turning circle with a quad which would be shorter ?
If you look at the next few pages I tried very hard to joint to existing bike frames together for a quick and dirt quad.
I did not go through with it for the following reasons :-
a) very hard to get in and out of the seat.
b) the existing frames had almost no tubing in the right place and by adding even more tubing it was just getting heavy for no real gain at all.
c) there was interference between the pedals/feet and the front wheels [ bike frames I used were much to short !]
I am not sure did I understand well your following sentences, especially the first one:
<"If a tadpole NO brakes on the rear , UNLESS a simple brake for parking they are dangerous ! [ NO commercial manufacturer sells a tadpole with only a rear brake ]">
With me it is right to have brakes on all wheels, not mater of configuration: quadricycle delta-trike, tadpole-trike - and, I will find a way to instal them on the front wheels too. However, a lot of Zombie's HPVs do not have brakes on front wheels? I discussed that (with myself) in your thread about "Different HPV". Many amateurs also do not have brakes on the front wheels. Yes - steering and suspension is simpler and cheaper if there is no brakes at front. All of the components must be stronger and of proper scheme and construction - with brakes.
However, do I understand well that tadpole trike shouldn't have brakes on the rear wheel, except simple brake for parking?
Well, I red all again and think that now understand well: beside rear-wheel brake tadpole trikes must have front brakes, especially if had simple/parking brake at rear!!!
<my English is not so precise and rich as before!>
--- ---
I do not know what I am doing wrong with photos? I think that my process is the same from the start. At first, photos on Forum appeared big, then jus as thumbnails an later just as links. I will study your explanation again and practised in special topic - chatting. I was registered, got password and when wanted to log-in - couldn't! Maybe that is a problem?
P.S.: What is average angle of wheels during turning: 20-30-45° ?
Ciao
So I need to find you some figures for a pedal box ?
Can't say as for me it is very big [ the Python ] oh and it very hard to measure
Also you can loose some of the ' what's available ' wheel turning angle when designing the steering linkage
Paul
