Ultra... pedal-powered quadricycle for senior

If you are building something near 50kg you will need to be in s very flat area and/or will need electrical assistance. Trying to pedal such weight uphill will be a killer even for a young person in top fitness. You will need a lot of gears with very low gearing to even begin to shift it. I would advise anyone to aim for a 25kg limit without a motor.

Pedalling any recumbent uphill is harder than a regular bike and the last time I looked Switzerland wasn't flat.

On a tadpole your weight is 2/3 over the front wheels. When you brake your weight can go entirely over the front so the rear has zero grip. In a corner that means even mild braking will lock it up meaning the rear overtakes the front and you crash. The same will apply to any quad using the same seating position. If you want rear brakes you will need to get your weight further back than a standard tadpole design allows meaning a longer wheelbase meaning more chassis as you then place more weight over the chassis rarther than the wheels. It also means your feet then want the same space as the front axle meaning the front wheels then have to go much further forward still so the pedalling space is behind the front axle meaning even more chassis. Negatives all round just to get unnecessary extra brakes which themselves add weight.

It is the easiest thing to add weight you can not move.

3 wheels will always make contact on even the most rough ground. 4 wheels will not. There will be times when a 4 wheeled vehilcle will lift a wheel. Suspension will help with that.

I rarely see any recumbent using full front forks that looks good. They almost universally look like they are a compromised design because the designer would not use single side mounted wheels.
 
Thank you, Popshot on clarification many issues with home-built HPV, especially my own quadricycle!​
Well, from Bern I could see Alps 60 km away - but I would not going there with any kind of bicycle, neither to "small hills" as they called them here, that are 1.500-2000 m high. I saw bicyclist enthusiasts cruising up such hills (we were in our automobile). Hard work indeed. However, there is highland from East to West with average hight of 550 meters above see level. There are smaller hills too, but I would not go so far away. Bern is relatively flat with some hilly streets, but I could avoid them going around. I saw bicyclist on MTBs (mostly) who have pain climbing such streets, but good that such streets are short (noticed that some do not know to use derailleur speed change in proper way).

Another note, I will drive/raid in relaxed/pensioner way as much as it is possible. No fast driving, no quick change of direction, no hard braking except in emergencies. But I must have good brakes for any situation, because of big total weight and heavy traffic on streets, even on bicycles paths and lines (bicycles strictly with a lot of electric-scooters). Therefore, brakes on all four wheels would be welcomed. I already have them on 26" wheels (one drum brake, could be used for parking too) and one contra-brake (coaster brake).
I will test strength and stiffness of the wheels - on parking, during harder cornering, without too much witnesses. I hope that front MTB 20" wheels at front would survived and at lest one of 26" wheels at the rear, so not to have bad accident. If 26" wheels show weaknesses, I would use 20" wheels at rear, too...

I think that C.G. will be at the half distance of wheel-base d of around 155 cm ~61", different to most of the tad-pole trikes, with recumbent seating (I will have more upright seating position). Pedals behind the front-axle. I think that I will have two rear wheels very close one to another, having almost three-wheeler footprint on the ground. It would be something as "reverse-trike" that are sometimes called. All wheels should be supported on both sides and all four wheels would have flexible suspension.

However, weight is big problem: my weight is now 98-99 kg ~ around 218 pounds, and couldn't be much lower! And, for sure I am not in athletic/sport form and condition, never was and now I am 74 year old. Without some ultralight modern high-tech materials for chassis, I couldn't go lower of 25 kgs ~ around 66 pounds. Electric assistance - maybe for the third HPV, if ever started. There is category of "Rickshaw", with possibility to have el. motor up to 2000 watts!

For sure, I must abounded (for now) my old dream to have Mochet Velocar, and just have simple backbone chassis (or two parallel sides of the same mass)… I have a hope that weight of "tad-pole quadricycle" should be much less than my old quadricycle that has 52 kgs ~114.6 pounds. And, I lost some 15 kgs in last years!

Now, I have a lot information, get here in Forum or by P.M.s, so I could think more, plan more and after making some sketches I will start to construct some components in basement that could later be assembled on balcony (from balcony - stairs to grass-field and the path to the street, behind our building). Therefore, instead to write my blog here (it helped me more to clear my ideas and got other members ideas, than to help anybody else)… I will ask some questions from time to time, when appeared some issues that make me dilemmas...
Ciao, ​
 
P.S.: Just to add for this for the end of writings:
  • "I rarely see any recumbent using full front forks that looks good" - quite true!
As I will not have one-side supported wheels, then bicycle forks are one of the solutions for precise and quality front suspension, but not the only one for two-side support of wheels... I will check something else as possibility for the front-wheels, for the rear-wheels I have solution!
  • "There will be times when a 4 wheeled vehicle will lift a wheel. Suspension will help with that." - quite true!
As I will construct HPV with four-wheel suspension and rear-wheels close one to anther, almost as three-wheeler, I hope that I would not have problems. Driving only on flat asphalt streets and roads around (no off-road rides) shall help! Bumps and holes are very rare, wavy surface too, so climbing on curbs could be problematic! However, I would avoid that in rides, just pushing HPV over it, up or down...
Ciao​
 
Have you found this ? Lots lovely old French stuff

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Look at the front forks ! this would solve a few of your problems if you could implement it ?
Oh and does not look particularly crude ?

Paul

ps I am sure there is more to discover :)
 
Having two rear wheels close together does little for extra stability over 1 rear wheel so you really ought to still be between the front wheels for best stability. However you are going long wheelbase with the pedals behind the front axle meaning you are sitting close to the rear wheels which are close together so you are getting outside the stability triangle particularly if high up.

The longer the wheelbase the heavier the chassis. Not only do you have more chassis but that chassis needs to be stronger as it becomes a longer beam thus has more forces to resist.
 
For an idea of length of such a machine look at the streetfighter design. Now add in 3" of extra rear wheel diameter and then slide those wheels back until they fit behind the seat. There may be a couple of inch to play with at the front but the only way to shorten it a lot is to go wide enough on the front axle to allow the pedals to clear the front wheels on turning or restrict the steering to avoid the pedals. The longer the wheelbase the wider the turning circle so restricting steering isn't ideal, leaving going wider as the better option. Check any obstacles (if any) on cycle paths for widths

It's worth checking your local laws. Many countries class four wheeled contraptions differently to three.
 
Hello, Paul!​
For sure that I saw it and saved it special Velocar folder, divided in a few classes, by model and style of Velocars. Velocars are my old love, from the early sixties of MY century, so in era of internet, I gathered a lot of Mochet Velocar photos and a lot of similar French Velocars as a copy of his, developed especially during WW2 and German occupation of Paris (no "benzin" for the people)! A lot of Velocars became electric powered and transformed to three wheels (no rubber tyres for the people)…

Before Internet, just some rare photos and sketches from magazines. The first was from Russian magazine dedicated to all kinds of DIY technique, with a huge article about Velocars. They were constructed at homes or Popular Technique Clubs, mostly in far away periphery of the USSR. They were used for daily transport: neither autos there for the people, nor motorcycles with side cars, like Ural or Dnieper. Used entire year, they had bodies similar to Velocars, but closed: protection from coldness, snow, rain, wind, sun! Most bicycles components, but often used sliding or hanging or standing pedals, with chains, cables and so on...

Shown suspension/steering system could be used if I decide to cannibalise my old quadricycle (not cute, not elegant, but practical). This one had quite wide body (two persons seating and pedalling), with not a lot of place for turning wheels left-right? I suppose (but have to make drawings with calculation of steering geometry) that 30° would be proper angle of turning wheels on king-pin (a little more on inside-wheel and a little less on the outside-wheel). The same, I have to calculate space for pedals: up-down, left-right, forward-backward (cube for feet and cuboid for the rest of legs) no mater of chassis layout. No problems, I found in basement cut piece of frame with pedals from mentioned teenagers MTB. Saw somewhere here in our Forum experiment with such component on cardboard and one empty shoe!
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Hello, Popshot!
After your previous message, I was thinking a lot, then made some calculations on paper and found that my pedals must go forward, at least between front wheels, have to check how much... Some older calculations and experiments show me that I need around 110 cm ~ 43.3" from further position of shoe on pedal to backrest. As "everybody knows, so do I", vertical line form my belly-button should positioned my body C.G, above a chassis and on a surface, with almost upright seating position, not recumbent? I didn't calculate C.G. of vehicle, but it should be around 1/2 of wheel-base... Anyway, vehicles weight is around 1/4 of total weight. With 160 cm wheel-base, I hope that could have total C.G at around 50-55%, measuring from the nose of the vehicle. With low seat as possible and gentle driving around corners, I hope that C.G. should stay in frame drawn by wheels position on a surface. Something longer wheel-base shouldn't help a lot for better weight distribution, but widening of rear-wheel position could help in a case of base similar to three-wheelers. Better to check that on diagram than in reality. Wider position of rear wheels - more complications and more weight, the same as longer wheelbase. Some compromises must be made. As we could see on Zombies' gallery, many successful and safe vehicles are mad on brad's plans, of diverse layout and construction, on three or four wheels. If there were still problems (on paper): moving of the pedal-system froward as on majority of tadpole trikes - could help (full feet-forward position)?
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This time, probably without Velocar body, in spite that it could be construct on any solid frame (wood, steel, aluminium...) as many replicas are built. Now, simple central wooden backbone, or two parallel girders of the same mass...
Still time to consider of all issues and try to find solutions. I will ask questions, from time-to-time...

Good night!​
 
Popshot! Just saw this (my writing is slow):​
"For an idea of length of such a machine look at the streetfighter design. Now add in 3" of extra rear wheel diameter and then slide those wheels back until they fit behind the seat. There may be a couple of inch to play with at the front but the only way to shorten it a lot is to go wide enough on the front axle to allow the pedals to clear the front wheels on turning or restrict the steering to avoid the pedals. The longer the wheelbase the wider the turning circle so restricting steering isn't ideal, leaving going wider as the better option. Check any obstacles (if any) on cycle paths for widths. It's worth checking your local laws. Many countries class four wheeled contraptions differently to three."

Useful as other writings!
I will check everything mentioned! Our laws here are quite liberal to bicycles on 2 or 3 or 4 wheels. There are restrictions for vehicles with gasoline or diesel engines or electric-motors, for HPV - not. Only, bicycles paths are wide from 80 cm up to 100 cm - they are without any obstacles and often long indefinitely, from the City to nearby villages and towns, than further away. Young and fit rider could cross entire Swiss in all directions, staying not far away from settlements...
Four-wheelers with distance between rear wheels less than 46 cm ~ 18.1" are in a class of three wheelers, but for pedal-powered it is not of importance. I will recheck my ideas of front-wheels distance. Probably would go wider than I planed... That is simplest solution for a few problems.
With this configuration I would add all lights that is necessary for motorised HPVs, for my safety and safety of other.

Regards for everybody that contributed with advices and comments! Saying just "bravo-bravo" is not of much help and could be dangerous!
Ciao​
 
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Hello, Paul!​
Yes, I saw it some days ago, but even if it is here in Br, I wouldn't buy it:
  • too expensive,
  • too heavy - 110 kgs;
  • too big head-wind resistance and even worse - sensible to side-winds, naturals or by buses, lorries and cars;
  • do no need it in such configuration - I like Velocars, but not too much of such configuration;
However, interesting wooden construction and with 1000 Watts electric-motor could be movable (on pedals only, hardly)…
Ciao, Zoran​
 
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"I just clicked on your link above right clicked on the picture selected Copy Image Link and used Ctrl P then Ctrl V and here it is ."
Paul

0-Olgicin-bike-1.jpg


0-Olgicin-bike-2.jpg


0-Olgicin-bike-4.jpg


Well, Paul,​
It seems that I learned this time?​
So nice good-by for old 2024 and so good way in to 2025! I just started preliminary sketches for new HP vehicle, according to your measures of "virtual box" for pedals, feet and lower part of legs, their position to the ground, with position of the seat (to the pedals and to the ground)!!! (everything adjusted to measures of my big body)

On the upper photos is beautiful bicycle got from my older stepson, broken during his of-road rides. He bought new one, electric - and this one we planed to adjust for my wife, adding "learning wheels" (nobody learned to ride with them?)… Plans abounded and now it would be cannibalised for my new quadricycle! It has nice 26" wheels: diameter is around 70cm, the front one has good drum-brake, nice to be used as parking brake at rear axle, the rear one had inside 3-speed gearbox and contra/coaster-brake! With 7-speed derailers as middle jack-axle - there would be a lot of possibilities to balance between speed and force of pulling from start and uphill? (I hope so)
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Teenager-MTB-20-1.jpg


Teenager-MTB-20-2.jpg


Teenager-MTB-20-3.jpg


Teenager-MTB-20-4.jpg

On the upper photos there is already chopped teenagers MTB, planed to be used for my wife's grandson! But she didn't like such "freedom" for him with so serious pedal-car, so I built him simpler kid-car, without pedals, just steering! Therefore, its components are waiting to be used for my quadracycle, too! It has good 20" wheels ~ diameter 50cm that I will use at front... There is one more wheel for reserve and one to be chopped - I need its derailleur system and hub as middle jack-ass!
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I still have dilemma should I cannibalised my old quadricycle for needs of my new quadricycle: at the first place to use front steering-heads and wheels forks, modified to use 20" wheels instead of original 26" wheels! I should have good and precise steering, braking and suspension. Couldn't know would that be lighter (and simpler to construct) than self-built system (I had plan for that, too)… Maybe complete of two handles for direct steering with most of the commends, and one of the pedal-heads (this is known ad B.B.?)too?

www.instructables.com

HPV-QUADRICYCLE FOR TWO

HPV-QUADRICYCLE FOR TWO: BACKGROUND When I was a boy, I dreamed about my bicycle, but never had one. During my childhood and early youth (fifties and early sixties), bicycles are rare in Belgrade, Serbia, old Yugoslavia - there were just a few around. I lived in center of …
www.instructables.com www.instructables.com

Happy New Year Eve for all of the people that still are waiting them!
Paul, thank you for advices of all kinds and a lot of patience!

Ciao,​
 
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Paul,​
One more oddity - Serbian fellow made recumbent tadpole-trike! Interesting central backbone: round tube, bended where necessary!


It seems to me that it is made in smaller town (periphery) or village in north part of Serbia - flat land, good streets and roads. Riding bicycles - tradition long more than a century! Every family had a bicycle, mostly just one big man's bicycle that all of them use... Kids ride it standing on pedals, on inclined bicycle and one leg through the frame.
This recumbent looks quite good and obviously he enjoy, the same as family and fiends.
Now, I am going to sleep - more from me tomorrow; working day for thinking about my HP-Vehicle!
Ciao, ​
 
Хелло, Паул!​
Hello, Paul!​

Interesting and unusual retro-style/ret-rod/steam-punk recumbent tadpole trike! There is many ways to realised old dreams, in one of the possible variants? The most important - constructor is satisfied and happy!

Unusual big and heavy front-wheels, probably of some old-timer, either from automobile or from motorcycle. Strange front axle, not very visible suspension if any and steering, too... Pedals are behind front-axle, even out of front wheels space? Seating at rear, near rear-wheel, no fear of instability? Hand-brake - good!

Central chassis of plywood could have any shape, to our will, if obey structural requests! So, one small "radiator grill" and bonnet/hood plates are possible. Painted cardboard is light and cheap but only for sunny weather? One head-light from Citroen 2CV gave nice charm to this auto. Of course, it could be remodelled to four-wheels. Many four-wheel Velocars from pre-War era were reconstructed to three-wheelers (no tyres enough during occupation), and - to electric power (no gasoline for civilians)… After the War, they were again transformed in to four wheelers with gasoline engines!

P.S.: Still have to think about such recumbent seating position (maybe angle of 45° from horizontal), with head-rest? Would it be good for my old and big body? Maybe unusual - but conformable? Is it easy to seat-down and stand-up? Position of rider's C.G. could be lower, but also a little farther than with "normal" up-right seating? Is back-rest support during stronger pedalling the same as with upright back-rest (not quite vertical, maybe angle of 80° from horizontal)

Ciao,​
​
 
Thank you for that information, I will discuss that with myself, maybe even to tray on model, full-sized! I was afraid of standing up and seating down, but I could see from all of light and short tadpole recumbents that many members use, that seats are not so low! Probably that level of the seat is accordance with level of pedal-axle (B.B. - distance from the ground?)… Therefore, shouldn't be a problem?
Ciao,​
 
Hi there

My 2 pence worth....

My seats are usually angled back about 45-55' for urban riding , the actual angle the back of the seat CAN be tilted back is limited by it's angle with the seat base , the closer that angle is to 90' the more upright the seat has to be else the front of the seat digs into your thighs.

Another factor is BB height to base of seat height:-
a) because if BB is to low again the seat front digs in to your thighs
b) I find if my BB is lower than the seat front I feel I can't put down as much power as when it is level with or 4-6" above it.

Getting in or out is just a problem you need to find a solution for as low down is safer , more stable and allows the quad/trike to be narrower without being unsafe.

DSCF5935.jpg
Both my Pythons have a handle like this on the front , it is very useful as you can lift the front wheel off the ground to manoeuvre it around , mount some lights on it , speedo and pull yourself out of the seat with it !

Don't sweat the CofG no one I know really bothers much about it's position when you have the available hardware in place and inserted yourself so you can reach said hardware there is little you can do to change it , the trike rule be as close as you can to the widest part of it's stability triangle is ignored on a quad !

Paul
 
Hello, Paul and Undertoad, and thank you for opinions and advices, now and before (other members, too)!​
So, I will try with 45° backrest (suggestions and photos with recumbent HPVs), horizontal seat base-plate (as I saw on many photos) and higher pedal-axle than front line of the seat (suggestions and photos)! During period of static and dynamic testing, entire seat could be movable/adjusted, then fixed just for me, in a way:
  • entire seat movable a little forward-backward (a couple of inches);
  • changeable the height of the seat from the ground (lower as possible, but in accordance with pedal-axle height);
  • changeable angle of backrest;
  • step-on and step-out should be tested statically, in the basement (no witnesses), some handles, here-or-there would be helpful;
Well, this will help a lot, as many information and sketches "stolen" from Paul's other topics (mostly about renovation of racing quad and evolution of trike into quad), and a lot of other member's comments!

I still have two dilemmas for better sketching and later testing (seat's issues):
  • could entire seat be suspended on some springs, to have better comfort and less "pain" for running chassis (my weight is much bigger part of total weight); some members wrote somewhere that it is not good solution (not enough of support for pedalling?);
  • with feet at the further position of pedals - legs are not straight, but have some angle in knees (I learned and used to press pedals with the middle of the foot, wrong?)? My measure from the base of backrest to the tip of shoe on pedal is130cm?
About C.G. - no need to think too much:
  • Trikes must have 2/3 of the weight on the axle with two wheels (the abs of foot-print triangle)?
  • Quads do not have such issues: weight could be at the middle of the wheel-base (theoretically ideal?), or 60% on front-axle or 60% on the back-axle, or anywhere between, depending on general layout of HPV machine? (should be symmetrical left-right distribution of weight?)
Enough for Saturday evening, from me!
Ciao,​
 
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