Building a Quadricycle...

[irw]

Thinking of building a Quadricycle...

Hi peeps, I hope this is the correct place on the forum for this query, I couldn't really see anywhere else it would fit in...!

After watching a couple of episodes of Chucklevision tonight, I've had a sudden urge to start thinking about using a quadricycle!

Now I've found a few sites on the internet such as this one which give you details of how to build your own and I must say that I'm intrigued, however I was wondering if anyone could advise on the ins and outs of using such a construction on UK roads?

Would it be classed as a larger than usual bicycle and therefore perhaps just draw some funny looks, or would I be likely to get pulled over by the police as soon as I get out of the garage?

Also, if my spur of the moment idea ever gets off the ground, do you think that it would be wise to take out some sort of insurance policy?

Thanks,

Ian

 

[spiro]

Ones like this are quite a common site around various Spanish tourist resorts, some have 2 seats other 4. Kevin at D-Tek has a quad that I am sure he would be happy for you to look at to get some ideas, he may have some ideas of his own.

 

[twentysix by twentyfive]

I think you'll be OK on the road. It won't be any wider than a tricycle (not much) and certainly not a car. Go for it say I

 

[Piemaster]

but you've only just joined the forum and admitting to something that embarrassing already?
Not the quadricycle, that sounds quite reasonable to me (I quite like the brox workbike recumbent quad) BUT watching Chucklevision?

Can't help but wish you well. Sounds like a fun project.

 

[irw]

Thanks for comments so far!

but you've only just joined the forum and admitting to something that embarrassing already?

Thanks for the welcome, but I have been around for about six months now! I've just been lurking!

 

[twentysix by twentyfive]

Well when you have completed your quad you will be required (by forum law) to tell us all (with pics) about your build and your plans to ride it. That'll put a stop to your lurking

 

[LeeW]

Hmmm, not sure if I would trust pvc plumbing pipe myself.
You may find this site intresting though http://www.quattrocycle.com/

 

[irw]

Right...well I've now got a design together which I am fairly happy that I can make work- I'm sure it's probably a bit over-engineered in places, but having not done that much metalwork before I think I'm going to err on the side of caution.

Below are a few screenshots of my initial CAD work.

There's no steering mechanism drawn yet, as I'm still trying to get my head around the geometry of it, and the angle of the seats and exact positions of the bottom brackets will be set once I start building and testing.

The main structure will be made out of 3"x1"x10swg (3.25mm) aluminium tubing.

The lighter grey bracket-ty looking bits are 2"x2"x1/4" aluminium angle.

The rear-wheel supports will also be made from the 2"X2" angle.

View from above/stoker side:

View from above/behind:

View from above/pilot side:

View from above/front:

View from below/pilot's side:

View from below/front. Many of the 2"x2" brackets can be clearly seen:

I intend to bolt the whole thing together, (hence all of the bracketry) as opposed to welding, as I have very limited welding experience and going by what I have read, aluminium welding is not for beginners.

Obviously, the chains are not shown on these drawings, however I'm planning on simply using two rather oversized chains to go straight from the cranks to the cassettes. I did originally start designing with the back wheels pretty much in line with the front ones, then decided all of the extra bits required to make it work would just end up being too complicated & costly!

Any comments welcome!

Ian

Edited to add: to give an idea of scale, the wheels in the drawings are 20" rims, with MTB tyres, so round abouts 60cm in diameter.

 

[Charlotte]

A few thoughts from someone who has considered similar sorts of projects:

Not having a wheel at each corner could be Bad News. You're starting off with an less stable vehicle and for the cost of a couple of transfer gears, you could build it right from the off. It also looks a bit odd.

Steering geometry - how will you make sure that your machine goes round corners? If you've not understood why a four wheeler needs Ackermann steering, you're going to have a sod of a job.

Front wheels - whare will you get single-sided hubs from? Sturmey do some nice ones, as used on a lot of recumbent trikes. Which leads me onto:

Braking - are you going to just brake the rear wheels with calipers? If your machine is reasonably heavy, will this be enough?

Wheels - if you're planning on using standard bike wheels for this machine, you may also encounter issues. You're going to be putting a lot more sideways forces through your wheels compared to a two wheel machine, so you're going to want to look at string rims and hubs with a high spoke count to offset this.

Different size riders: What's going to give - the seats or the bottom brackets? How are you going to make this work?

I'm really interested in the idea of a light weight, practical two-seat quadricycle. There's absolutely nothing on the market that comes even close to the sort of quality that you'd see on a Trice or a Windcheetah. Which is a shame, because quads could be a fabulous transport option for people who don't like bikes.

Also, it would be a cinch to add electric assist...

 

[Hilldodger]

We have a very similar machine at Cyclemagic.

 

[irw]

Thanks for your comments, below are my thoughts on what you have said:

Not having a wheel at each corner could be Bad News. You're starting off with an less stable vehicle and for the cost of a couple of transfer gears, you could build it right from the off. It also looks a bit odd.

Point taken, I'll have another look at this.

Steering geometry - how will you make sure that your machine goes round corners? If you've not understood why a four wheeler needs Ackermann steering, you're going to have a sod of a job.

I've been doing a lot of reading up on this, I hadn't quite got my head around it when I saved those drawings, but I've got the theory now, I just need to CAD up the measurements

Front wheels - whare will you get single-sided hubs from? Sturmey do some nice ones, as used on a lot of recumbent trikes. Which leads me onto:

Hmmm...something to think about there. I have picked up a couple of cheap bikes from ebay, but the axels are standard solid axels that came on them. My reasoning for using these wheels was that should they break, new spares should be available easily. I will look into creating some sort of wheel arch with a pivot point above the wheel for better support.

Braking - are you going to just brake the rear wheels with calipers? If your machine is reasonably heavy, will this be enough?

V-Brakes (the same used on my tandem)will be attached for use on the rear wheels. If I adapt the front wheels as above I shall mount the same type on the front as well.

Wheels - if you're planning on using standard bike wheels for this machine, you may also encounter issues. You're going to be putting a lot more sideways forces through your wheels compared to a two wheel machine, so you're going to want to look at string rims and hubs with a high spoke count to offset this.

Again, point taken. I'm not planning on doing any off-roading, or especially speedy riding. As I have these wheels sitting in the garage anyway, I'll probably use them to start with, and when spokes start pinging I'll say you told me so!

Different size riders: What's going to give - the seats or the bottom brackets? How are you going to make this work?

D'oh! The plan was to make the seats moveable, however now that I've moved the back wheels in, that plan has gone out the window...back to the drawing board on the back wheel positioning I think!

I'm really interested in the idea of a light weight, practical two-seat quadricycle. There's absolutely nothing on the market that comes even close to the sort of quality that you'd see on a Trice or a Windcheetah. Which is a shame, because quads could be a fabulous transport option for people who don't like bikes.

Also, it would be a cinch to add electric assist...

Electric assist is on the second phase of the build, once I've got a working quad! Thanks a lot for the comments, I'll go back to the drawing board on the bits I've mentioned and post some more renderings!

Ian

 

[Hilldodger]

V brakes just won't stop it - you'll need hydraulic discs on the front.

Believe me, you will. Even with Sturmey drums on ours it takes some stopping.

 

[Charlotte]

Have you got a picture of yours, Roger?

 

[arallsopp]

Have you got a picture of yours, Roger?

+1. Would be very interested to see this.

 

[Hilldodger]

<Rummage>

Got one somewhere.