The Velassi

Edit:27 sept. 2019, Cre:21 juin 2019

The Velassi

See also details and tips
The Velassi, a not so reclined recumbent (but more than a ‘semi-recumbent’).

That, this is when you can’t choose
between the bike and the couch.
Anonymous seing the Vélassi
Here you see, he pedals and he take a nap.
Another anonymous
Hooo, to tan you shall go to the beach, sir.

Build a recumbent

Why a recumbent ?

  • To avoid butt pain
  • To look to the landscape and not to the road
  • To avoid neck pain
  • To avoid wrist pain (that I damaged abusing of hammer drill while renovating my house)
  • To improve aerodynamism compared to an upright bike (Which shall be very upright due to my wrist troubles)

This, finally allow larger range of bike rides.

Why a not so reclined bike ?

  • To ease first handling
  • To avoid clipless pedals
  • To limit neck angle and avoid head rest

Why a wooden bike ?

  • Why not? Practically, because I don’t have equipment neither experience to TIG weld or braze neither to build a composite frame, and that I have a limited experience of wood-epoxy building. That is a technical choice and not as for many wooden bike builders, a will to create a work of art (How come, you can see that ?). The philosophy of design of this bike is more inspired by aircraft building than by other wooden bikes that I was aware of. Indeed, if I was more respectful of aircraft building know-how, my bike would have been lighter, I will came back on that…

Is there a motor?
For miscellaneous reasons, a lot of people are persuaded that there is a motor, but no… The big rear hub is a geared hub (8 speeds) and the front hub is a dynamo.
When I have time to answer, I just tell: I am the motor!

On a long chain line, you can set up a motor in diverse places. A side mount motor with incorporated freewheel of this kind is really easy to install but they are very low quality equipment and to be legal in my country, you shall install a command by pedal switch only.

A mid-drive motor like the Tongsheng TSDZ2 (with torque sensor) or a Bafang BBS-01 (with pedal sensor) might be better but they cannot be installed on the present wooden frame because there is no sufficent bottom clearance, but the future wood frame have been redesigned to allow a mid-drive motor.

Images



To that:



From that:



While doing that:


Building details





Specifications

Specification of built bike (small size, for inseam between 73 and 80 cm):
Wheelbase : 1650 mm (65”)
Front wheel size 20” (rim size 406)
Rear wheel size 26” (rim size 559)
Seat bottom at 520–540 mm from ground
Bottom bracket 120–140mm lower than seat bottom (400mm from ground)
Crank arm length: 152mm
Trail 75mm → to know how to choose trail see an online calculator

Transmission with geared hub (Nexus 8) with simple chainring. Very short gear-inch: 196” in 8th gear (=development 5 m), I did not pedal while descending.

I did modeled multiple frame types and among them a monobeam frame but pratically two scissor trellis frames, one in wood and the other in steel looks preferable while remaining reasonnably light. Loads on a long wheelbase bike are not negligible and I did not trust much a monobeam frame while this was already done.

Publication

As for some of my other projects, I have the intention to publish the model (made with OpenSCAD) and information about building. The bike is at its beginning (first run in may 2019) and there are modifications to do, I feel I am still in debugging phase and I am still modifying the model, so you will have to wait and came back from time to time if you are interested. There will also be development of the Internet pages which also are at their beginning. I shall make a preliminary evaluation of the building and handling and practically my intent is to rebuild a new frame. Model will incorporate steel frame, however I have not yet any intention to build a steel frame.

Building in wood

Building in wood:
This is a bit a choice by default as a steel frame might be slightly lighter and less sensitive to weather. That was also more simple for me as I already have a small experience of epoxy-wood building and associated difficulties while I yet have to learn to braze.
I also liked the idea of a wood building.
We know how to do very strong glued joints, stronger than the wood itself since the invention in 1943 of resorcine-formol glues which are practically stronger than epoxy but need very well adjusted parts and strong tightening during drying. Wood aircrafts are nowaday only built by amateurs, but there was wood built light aircraft till the end of the XX century, including aerobatic airplanes.

Welding/Brazing steel structure

Brazing shall always be preferred to stick welding or flux-core wire welding for resistance and metallurgic quality. When it is well done (no excess heat), a brazing have the advantage to not drive to thermal modification of base steel. TIG welding allow high quality welds but you need argon gaz (and it is also required to inject argon inside tubes). To have quality MIG weld you need BOTH gas and flux-cored wires because gas only creates inclusions. Beware, the rod metal for brazing steel is different from the one used for copper welding, you need specific rods which is not always well explained.

Modelisation

As all my projects since four years, this was developed on OpenSCAD and is entirely parametric, but yet there is only one pre-defined dataset for small size, the one built. It is relatively complex to develop a dataset and you have sometime to dive in the program to chack what the data is modifying.
OpenSCAD had evolved and since more than one year there is a module to easily enter parameters named ‘Customizer’ which is quite comparable with the Thingiverse customizer (Thingiverse is a large library of 3D printable models). There is no limit to the number of datasets which can be recorded.
Modelisation was by far the longest step and the one which takes most hours, it have taken me multiple month. To avoid surprises and too frequent modifications, I always do quite detailed models.
The big advantage of OpenSCAD is that it does allow relatively easily to do parametric models because the model is in fact a program. Creating parameters need significant complementary work but allow easyfurther modifications. These are parmetric models which really give the interest of computer modelling.

2D projection (drawings) and cuts

On this model, I did more than a simple computer mock-up and also created a module projecting the beam shapes on drawings. I then use a CAD program to add dimensions. I then printed beam shapes on paper, cut the shapes with scissors and glued the paper on may wood planks. I cut the beams with a track saw with the help of a jigsaw for contoured elements. A track saw is very precise and you have no need to rework the straight cuts. After drilling, I did a pre-assembly to control structure. The rounded edges were sandeed by hand which is quite long with oak hardwood. A table tank and disk sander is required but I did’nt have one when I started the manufacturing.

Transport the bike

Waiting the development of a foldable back seat, to transport the bike, it is required to remove the seat. This is not very long, a bit more than one minute but you will need three to four minutes to reinstall it. To remove the seat, you need to disconnect the rear light. Without a plug (bought, but not yet installed), I used screw connectors for re-connection.
For a journey where I was alone, I have been capable to install the bike inside my station-wagon (with rear wheel folded), howevers mirrors were very exposed and I did broke the right mirror arm on the second loading.
If your car is loaded or if you have passengers, you have to install the bike on a rear rack. With rear wheel folded, the bike is shorter than a common bike but the handlebar may conflict with some type of racks.

References

General information

On this forum the Velassi thread
This forum is quite active and have a lot of technical information. Recumbent market is limited so there is probably more need for a place to share stuff than for upright bikes.

Other plans

Atomic zombie diffuse many recumbent drawings, including the WildKat USS that I did buy. I was not really convinced by these plans as they are relatively general and focus more on the manufacturing than on design details and neglect important elements. They recommend a given head angle without taking into account fork offset (rake) which varies significantly from one fork to another in 20” wheel size (typically from 30 mm to 50 mm), which will make a trail with significant variation depending fork parameters, so the handling will be somewhat random. Handling of recumbent is a complex problem where you can write a book, which was indeed done:The lord of the chainring I did bought (after building and some handling problems) the kindle version of this book but there is a big problem in the kindle version and formulas are not understandable. However, the book author (William Patterson) defined an equation advising a trail for a recumbent which can be found here. The recommendation of Atomic Zombie will give a trail notably lower than what recommand Bill Patterson, though the ‘wheel flop’ will be lower, which is more benefitting for low speed handling.
Also on Atomic Zombie plans, there is no recommandation about handlebar installation, which is shown by the fact all built WildKat have very different steering installation. For safety and ease of handling, I highly recommend to have the handlebar with a substantial vertical rise, in order to be able to maintain your body when braking. Indeed, there were reports of faceplants on really under seat handlebars without vertical rise.
The handlebar installation is one point were I expensed the biggest design time. I hesitated for a long time and was willing to make a double lever ‘tank’ steering. That may be better but heavy and very fragile, the lever support being really exposed when you fall (which WILL occur). I did create ‘amplification’ say the fork rotate more than the handlebar to take into account limited possible angle of handlebar.

On the other hand, Atomic Zombie publish a book:Bicycle builder bonanza that I bought used and that I recommend if you want to build a steel frame bike.

Long wheelbase similar bikes

  • The bike Fold Rush from Easy racer, long wheelbase bike with folding rear, but with above seat steering handlebar. Price 4000$ (which may end to 4500 Euros once imported in my country -France)
  • The bike Linear Limo, long wheelbase version with and underseat steering (really underseat, bars not rised). There is a disassemblable version to ease transport (2975 USD).
  • The bike Longbike Slipstream, underseat steering long wheelbase bike, however with a seat way too high for me even with the ‘Small’ frame. 2900$
  • The bike Rans Stratus With above seat handlebar, one of the most succesful long wheelbase bike. 2700$.
  • Sunseeker also build the EZ-sport,evolution of the EZ-1 which resemble the Rans but is built in asia, and sold for 1410 USD
  • Bachetta also sells the Bachetta Bella with a geometry very near to the Rans one, but a slightly different design for the frame.
There was Lightfoot mountain long wheelbase recumbent but they are no longer produced.
An amateur (Richard Ehrlich) had remarkable mountain recumbents built for him.2 3 4 first built in aluminium then carbon fibre. He race with these bike.
Long wheelbase bikes for touring are mainly diffused in the USA, by opposition to short wheel base bikes, often more sport oriented which are monopolising European market. In Europe, touring demand for recumbent often drive to choose ‘tadpole’ tricycles, which may be easier to transport with good stability and good performances.
Recumbent sector is relatively confidential, and among them long wheelbase bikes are fairly rare in Europe. We are there is the ‘niche of the niche area’.
One main problem of recumbent bikes is that they are relatively costly which may be one reason why their diffision remains limited. Conservatism also maintain this situation.
It shall be noted that these US bikes costing more than 2000 to 3000 USD are delivered in standard without lighting nor mudguards, you still shall add some money for this basic equipment… This sort of thing makes me cringe.
  • The bike Longbike L3 rider from Fateba, built in Swiss. Instead of their north american counterparts, this bike is properly equipped, but its cost is 4180 CHF as a base price (around 3700 Euros). And it is still too tall for me…
(c) Pierre ROUZEAU
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