Low Racer tilting trike

During last year I have been able to ride more than 6000km with both my solar trikes (2018 STT and 2019 STT2) .

These are the 4 areas where I could gain a lot of significative experience: 

Tilting Mechanism:

after roughly 700kms with my STT2 it started to become noisy while the rotating pivot was pushed few millimeters toward the bottom part. This happened while I was riding on the SunTrip rally and therefore I have not been able to repair it effectively…

The only objective was to finish the SunTrip solar adventure even with a defective tilting unit.

Later I had to understand what caused this issue.

Confort:

I have ridden often through pretty bad quality roads and not having any rear dumping system was physically quite hard for my back 🙁

Stability:

I still felt that the center of gravity was a little too high, especially having installed 2 solar panels for 300watts (roughly 10kg including also the aluminium structure).

Motor overheating:

with Falco Direct Drive hub motor, installed on a 26″ front wheel (2018 STT) very often after few hundreds meters of altitude gain the controller cut down the power to around 280watts. This also happened quite often also with the eZee geared motor on a 28″ front wheel (2019 STT2).

After I came back I started to completely disassembly the Tilting unit.

This allowed me to appreciate all the damage that was caused by the issue decribed above.

I repaired the defective Tilting unit in such a way that the trike felt again very good when leaning into tight turns.

But this was not enough since this ‘rotating pivot’ could have caused again similar issues.

So I started to design a radically different Tilting unit.

I replaced the ‘rotating pivot’ by 2 connecting rods pulled by both Tilting arms.

On the right a short video to demonstrate how the new V2 Tilting mechanism is working

Here we can see the difference between the STT2 and the new Raptobike Low Racer I bought.

I decided that the new version for 2020 should be based on a Low Racer to improve handling, stability and also ‘ease of use‘.

STT2 versus Low racer

Here is the new V2 Tilting mechanism installed on the Low Racer frame.

We can see how the mechanism is neatly attached to the rear part of the frame. 

Since the arms are VERY close the new tie rods I had to cut few millimeters from the aluminium structure to let them move without any interference.

Here we also see that the arms are 5cm longer than previous version to increase the maximum tilting  angle to roughly 38° (from 28°).

Another area of improvement was the possibility to easily check that rear wheels are parallel. 

For this reason I have installed 2 tensioners, each one working on the axle on rear arms. 

In this picture we can see that by positioning a metal bar (38cm long) I can verify if both wheels are parallel. 

If not, using the tensioners I can modify each wheel separately. 

After few weeks I was able to start performing some tests and I could see that:

the Tilting mechanism V2

is very smooth, precise and the maximum leaning angle is reachable very easily.

the handling and the stability

are now excellent: it’s easy to go straight without both hands and at the same time the trike is very easy to turn.

– the confort 

is greatly improved with the new elastomer based suspension. After having tried tried different compounds (without solar panels, battery and hub motor) the best is the SOFT elastomer.

Here below we can see 2 videos:

– the first one to show the handling and stability of the Low racer with the new upgraded V2 Tilting Mechanism

– the second one to show the new ”elastomer” based suspension mechanism.

 

This Post Has 10 Comments

  1. salut mon grand Daniele : alors après notre dernier telephone, comme je t avais dis, ton tilting low racer est absolument le type de velocouché qui m intéresse le plus désormais, sachant que déjà depuis que je te connais et ai pu te voir evoluer sur ton ou tes raptobike équippés en tilting wheels, ces concepts de cycles me plaisent le plus de tout ce que l on peut voir en velocouché ou trikes …
    Je me réjouis si je pourrai très bientot aller te rendre visite et essayer ta derniere version, car j aimerais bcp investir aussi ds un rapto , low racer ss doute, à équipper des roues jumelées que tu l avais faites, pour ensuite, bien sur, l équipper en solaire …j apprécie bcp aussi la capacité de ta derniere version pour pouvoir ne pas mettre les pieds à terre lors arret complet … aux prochaines news et à bientot j espere …

  2. Daniele

    Wow the V2 is just what I am looking for.

    Could I ask for a few dimensions ?

    Axle to pivot point ?

    Pivot to connecting rod pivot ?

    Length of connection rod ?

    and width of bar between the 2 connection rod pivots ?

    regards Paul

    1. Hi Paul,
      Thanks for your compliments!
      Here are some of the dimensions you asked for:
      – Axle to pivot point = 50mm
      – Pivot to connecting rod pivot = 140mm
      – Length of connection rod = 130mm
      – width of bar between the 2 connection rod pivots; 35mm
      Are you willing to build a similar mechanism by yourself ?
      regards

      1. Daniele

        I ride a Python trike with 2 none tilting back wheels , however the seat is very low 20cm.
        I would like to raise the seat without making the trike more likely to tip over when cornering.
        I am currently building a iLean rear end to try , the problem is although it is a simple design the wheels are not in line and so the trike becomes longer and also they will stop me carrying my camping gear.
        Your V2 is like the iLean but due to the linkage the wheels are in line and so it is more compact and easier to built wide enough for my camping gear between the wheels ?
        I have 21 pages of ramblings here :- https://atomiczombie.com/forum/threads/my-life-with-python-trikes-mk1-mk1-5-mk2.33/
        regards Paul

        1. Hi Paul,
          Congratulations, I think you have put a lot of effort on developing your “Python” trike!
          I think that one of the advantages of the tilting trike is that there is some space that can be used to put my camping stuff between rear wheels.
          Here you can appreciate some pictures taken on my 2018 STT1 model: http://gonano.eu/rear-luggage-rack.
          Your trike has the distance between rear wheels much bigger than mine (38cm)
          Of course a tilting trike doesn’t need to be as wide as a ‘normal’ trike.
          This is why I have chosen to keep rear wheels not ver far from each other: overall objective was that TOTAL width should be below 50cm.

  3. Well, a leaning trike indeed is much stabler than a velo – you can lean into turn and have have an extra wheel in the back, that gives you cornering (provided you can lean far enough, like motoGP racers) that is limited only by tire adhesion, and with forward weight bias AND extra wheel in the back you have excellent traction.
    However, this is still a single track HPV – that require keeping balance on a second to second basis, and leaning not only into turns, but into winds as well – and with a huge side panel that is basically a flat plate (implying HUGE drag) that can be very tricky, and the higher you panel is – the more tilting moment it generates for a unit of side force.

    I’ve seen a reports on endless sphere of a guy who did HUGE touring with his tilting solar trailer – he used actuators and sensor to have track the sun like a sunflower, maximizing energy ‘caught’.

    IN fact, given adequate sensors and fast actuators, and turning the panel into a symmetric airfoil (say, NACA 0015), you can have 3 modes:

    1. Horizontal tracking to prevents side winds from affecting you. Amount of appropriate downforce force can be varied by changing the angle of attack of the airfoil and set up experiementally.

    2. Sun tracking mode – in calm weather, you can maximize your solar input but switching to this mode.

    3. SAIL mode in a moderate, steady side wind – turn it vertically! With airfoil section and large area, you’ll see a pretty damn huge sail force, even given low aspect ratios. For instance, velomobiles can ‘sail’ into a strong side/front wind w/o pedalling at all, you will have the same effect – but you’ll have to lean into the wind pretty far and may be prone to be toppled by a gust.

    By the way, by lowering CG, you’ll have less stability and less resistant to side winds. Do read the article I’ve provided. What you want is to lower your center of pressure (CP), but that will have to come in tandem.
    Fortunately, by having ’tilt damping’ (friction in pivot, you can add motocycle dampers) you’ll lean slower and have a wider reaction wind to wind gusts and truck suck – exactly what HIGH CG do, but w/o having a high CP.

    1. One of mine “golden rules” is to KEEP IT SIMPLE, since it is all about a bycicle (light and simple) and not a motorbike.
      Concerning few points you mentioned:
      “…provided you can lean far enough, like motoGP racers…” I started with a maximum leaning angle of 25°, it was definitely not enough: in my last version I can reach 38° leaning angle which is for sure an excellent compromise.
      “…by lowering CG, you’ll have less stability and less resistant to side winds…” I am not sure about your conclusion: this is why I am building a LOW RACER solar bike to be able to increase stability (especially when it is windy), agility and ease of use.
      “…this is still a single track HPV…” In my case it is not single track, since there is the one from the front wheel and 2 additional ones from rear wheels
      “…that require keeping balance on a second to second basis…” On a straight line I can easily ride without hands: as soon as speed exceeds 8 km/h the stability is definitely much better than a normal bike

  4. Hi Balor, I advise you to have a look at this video where you can see how stable is the trike with my tilting mechanism: https://youtu.be/46iQwh-iJik
    Compared to a standard velomobile the stability is much better!
    This is why I am working on a tilting velomobile 👍, I will post some photos in the next days hopefully

  5. I’m making my own tilting HPV, but a fully faired a diamond quad variety:
    http://www.bentrideronline.com/messageboard/showthread.php?t=147806

    Side wheels will be tilting with tilt lock, at least that’s the current theory, hopefull it will work out.

    Your tilting solar roof combined with this article:
    https://motochassis.com/Articles/Aerodynamics/AERO.htm

    Gives me an idea: turn it into a wing that generates moderate downforce, and utilize it to stabilize by rotating it around the x-axis like you do, but not to generate maximum energy, but to roll-stabilize a tilting HPV. Due to huge area it will be able to generate relatively large force!
    You just need a tilt sensors and a servo-motor.

    Very interesting if you ask me….

    1. Hi Balor,
      your project is very interesting, thanks for sharing!
      As far as your idea is concerned, I understand you propose to use a (solar?) wing to create a downforce in order to stabilize the vehicle.
      The first question to ask is at which speed this downforce becomes significative to effectively create a stabilization result.
      So for example I guess that at 10km/h this downforce will be very low so you won’t be able to use it for this purpose.
      When riding at 100km/h the downforce will definitely be relevant to create this ‘stabilization’….
      In my experience when the wind is significant (say at least 30km/h)my trike becomes very sensitive and it is not easy to keep a stable direction (of course with zero tilting in these strong conditions!)
      FYI with this new 2020 version I am reducing the front profile of solar panels (from 6 to 5 cells width) in order to improve areodynamics and reduce wind sensitivity

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