CKC

Custom Karts Forum

Audi Urban Concept (2011) scaled down to 1 person

AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
I have been following many projects on this site to get an idea of what kind of cyclekarts are possible. Thinking about what I would build was influenced by my experiences for 4 years driving/cycling a Sinner Mango velomobile with 170W electric assist to work. It is roadlegal for bicycle paths in the Netherlands, although it goes ~40 km/h instead of the legal 25 km/h maximum for pedelecs. My yard is not small but I would get bored very quickly if my project would not be street-legal. ;-)

Some of the disadvantages of the Mango which I want to solve are:
  • too narrow (only 76 cm wide) so it tends to lift a wheel in fast corners or even fall over.
  • too large turning radius
  • too narrow cockpit around the shoulders
  • too slow for a commute time similar to my car + traffic jam

When I came across the Audi Urban Concept I saw my dream cyclekart! It is a 2011 prototype for 2 persons, and weighs 480 kg with a 15 kW (20 bhp) electric motor that reaches 100 km/h (60 mph). It has 90 kg batteries holding 7,1 kWh of energy, resulting in a range of 45 km. Dimensions are 3,21 x 1,67 x 1,19 m (lwh).


It needs to be scaled down to ~80% overall and 50% on the cabin width to make it lighter and suitable for bicycle paths. My ideas:
  1. make it a single-seater, with a narrower body and also a narrower track (total 1 m wide should be enough)
  2. add cycling stuff so it becomes a pedelec
  3. use 2x 250W electric motors on the rear wheels but make it look like it only has 250W street-legal pedelec
  4. much less batteries, but enough for a 50 km range
  5. use lighter bicycle wheels
  6. use lexan for the front window
  7. no side windows and a roof from neoprene (like a kayak sprayskirt)
  8. lighter construction as the top speed will be lower too.

What are your thoughts?



Edited 1 time(s). Last edit at 2014-12-09 06:24 PM by MalibuMan.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Some of the styling from this fast velomobile I like too:

moto-klasika Avatar
moto-klasika Zoran R. P.
Bern, Bern, Switzerland   CHE
Hello Cas,
Quite interesting concept for "bicycle with assistance", according to standards of E.U. regualtives... I couldn't find anywhere that such "bicycles" are restricted to 2 or 3 wheels? Therfeore, quadricycle is possiblly legal...

Your variant of two electric-motors with power up to 250 Watts (one legal one not so), is fine for my taste.
What you planed for the chassis and what for the body? If all that isn't too heavy, with one person you should be satisfied with total of 500 Watts, at least for legal speeds of 25 km/hour and bicycles paths and lines. I prefere some classic look, but your choice is more aerodynamic, for sure. I do not know how it is important for low speeds, but it will help with small power.
Ciao,
Zoran




Zoran R. Pualić
(mostly living in Bern, Swiss & happy in my Belgrade, Serbia)

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Zoran,

The european vehicle classes are decribed here:
http://transportpolicy.net/index.php?title=EU:_Vehicle_Definitions

Roughly you can divide them in:
- pedelecs: must cycle before/while the electric motor helps, power is max 250W, and speeds is (gradually) cut off at 25 km/h.
- S-pedelecs: No need to cycle to get to 25 km/h, but if you cycle along you can reach 45 km/h with max 500W electric support.
- mopeds: category L1e (2 wheels), L2e (3 wheels) and L6e (4wheels < 350 kg) have a max power of 4000W, and max speeds of 45 km/h.
- motorbikes: category L3e (2 wheels), L5e (3 wheels) and L7e (4 wheels <400kg and below 15.000W) can go faster than 45 km/h.

As I want to use my cyclekart in daily life for commuting on bicycle paths, this leaves me the choice between a 3- or 4-wheel pedelec which goes only 25 km/h, an S-pedelec without the need for a helmet (until 2017), or a 3- or 4-wheel 'moped' with max 45 km/h (helmet mandatory). Beginning 2017 all S-pedelecs will be treated as mopeds, so must drive on the road where indicated (inside the city), but sometimes on bicycle paths (mainly outside the city). There is even talk that there will be high-speed (extra wide) cycling path between big cities, especially to promote commuting by e-bike.

So, although I currently hava a pedelec velomobile that goes ~ 40 km/h if I frantically cycle along (total sweat after 30 minutes = need to shower at destination) that is already illegal. But very cheap as there is no registration or insurance requirement. Because the S-pedelec will become moped anyway, that's not good either. So I will focus my build on the 'moped' category, with enough power to reach 45 km/h without cycling along. I can still go for the 2x 250W approach, but anything <4000W is allowed ;-) and any speed over 45 km/h is illegal :-( only if they catch me ;-)

On to your other remark, chassis and body. I want to borrow the cycling part from a velomobile which has a 40 x 40 mm aluminium backbone with glassfiber/polyester body. For the double wishbone suspension I need fixing points on the outside of the body at 2 heights. It will turn out to be a long rectangle, possible narrower at the front and maybe also narrower at the back, like a stretched-out hexagon. And that also ~ 20 cm higher, so I end up with a simple (and hopefully still light) version of a space frame. Being a space frame I might choose thinner Alu tubes to save weight.

For the body I want to calculate the difference in weight between Alu and glassfiber/polyester, possibly carbonfiber. Being a one-off, Alu seems easier, as for polyester you need to make a foam original, smoothen it, make a negative cast, and then make a positive end-result. Choices, choices...

mrspoom jim w
Osage City, Kansas, USA   USA
Looks like an ambitious project for sure; I have been working on a car with an electric mobility car motor with all its electrics. I'm going to use 2 - 21 speed rear sprocket sets one on the live rear shaft and one opposite on the motor shaft with a derailer (sp) in the middle of them for a seven speed transmission. The sprocket sets will have cogs to keep them from free-wheeling so I can have seven speeds in reverse.



Edited 1 time(s). Last edit at 2014-12-14 01:47 PM by mrspoom.

MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Jim, I thought electric drive does not need a transmission, other than a fixed gear to get your electric motor to high-rev and your wheels to go a bit slower.

Even the Tesla sportscar that goes ~180 km/h has no gears to change, you stay in 'first' gear.

moto-klasika Avatar
moto-klasika Zoran R. P.
Bern, Bern, Switzerland   CHE
Hello Cas,
Thank you on detailed explanation.
Some times ago, I found original text of European Union Directives that regulate classification of motorised vehicles! As generally adopted in Europe, even in Serbia that is far away from membership, they make simple for us to make decision what and how to make small motorised vehicle for our pleasure, on two, three or four wheels. Only, so-called "pedelec" and "S-pedelec" bicycles are not described in details. Probably, they are classified by national standards and laws? As version that no need registration, driving license and probably not any kind of attesting, they looks as the most appropriate...

However, as you said, maybe too much complication for not-so-practical solution, part because of limitation part because of small power. For two of us, power of 250 watts is too small, even if doubled that later. But, the most unpleasant restriction is system of engagement of electric-motors and its limitation. That means: now power when we need it the most – starting on traffic lights and hills. Then, no amateur improvisation (at least not for me), only buying of some kit-complete that is too expensive...

Therefore, I will consider “light quadricycle” as it is named by E.U. Directives – class L6e (developed from mopeds), with 50 cc gasoline engine or electric up to 4 kilo-Watts. Weight and speed restriction isn't issue for me... I could designed it according to developed Serbian technical standards made under E.U. Directives... Only, I am not sure for process and price of attesting it. On another thread in this Club, it is mentioned as 1000-1500 Euros. Probably in Swiss even more: too much for me...
--- ---
Hello Jim,
Your idea with transmission using bicycle's derailleurs looks attractive to me! Some sketches should be helpful. On another forums, I was told that such systems could easily accept power of more then 2 HP and for short time even up to 3.5 HP, with more often change of chains...
--- ---
Cas, again...
I was learnt too, that electric-motors do not need gear-changing, because have big torque from the start, as steam engines... (lessons about Nikola Tesla and his work, who was my compatriot). However, many amateur designers (some professionals too) from a few forums, think opposite: electric-motors work better and are more efficient with gear-changing of some type, beside electronic regulation? At low speeds, but with more amperes used – they spent more energy on heat then on production of torque and power... Some other say: nothing of that is necessary, only switch-off-on, but just for brush-type motors...

Ciao,
Zoran




Zoran R. Pualić
(mostly living in Bern, Swiss & happy in my Belgrade, Serbia)

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Searching for very light components, I came accross a site with gravity racer parts and building tips. As my moped-speed cyclekart will operate in the same speed range, their hardware may be exactly what I need.

http://www.formulagravity.co.uk/new_build.html

Does anybody here have experience with using gravity racer wheels instead of the motercycle wheels?

What do you think of the suspension? if OK, that will save a lot of time and work if OK...

mrspoom jim w
Osage City, Kansas, USA   USA
You are right but I am thinking that with the differential the electric motor is driving it will only go so fast and I have found that it needs to have a fairly small sprocket on the motor and a larger sprocket on the rear to get it going in a lower gear. Thus the gears; also when I went through the gears the rear wheels were going really fast! That kind of impressed me too! When I get the second sprocket set I'll get it set up and post a picture and maybe a short video to show what I mean.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Still undecided about the design, I found some historic cars that I like very much.

First, the Buick Bug of 1910, I love the nose without radiator and the closed wheels.





Edited 1 time(s). Last edit at 2015-02-25 07:15 PM by MalibuMan.

MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
Then the Miller Submarine of 1917, as it rains quite a lot - and can be cold - in the Netherlands, and I want to use it all year round.

The Miller also has a 2-person cockpit, so could be shrunk a bit.



Edited 1 time(s). Last edit at 2015-02-25 07:17 PM by MalibuMan.

MalibuMan Cas Tuyn
Weert, Limburg, Netherlands   NLD
About pricing, I saw a 3kW engine at http://www.goldenmotor.com/ for $288 and a 5kW engine for $416

I will first need to see how much my CK will weigh before I look at batteries.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Karts

1925 CycleKart Great Britain

Text Size

Larger Smaller
Reset Save

Sponsor Links