Quad build [ my own ] at last !

[Popshot]

A pair of turning circles for a swb and a lwb. They both have the wheels turned the same amount, and the same track plus the swb one takes into account the bottom bracket (yellow box) protruding forward.

 

[stormbird]

I feel your pain and have been there before with chain-line, diverters and derailleurs that hit the sleeping policemen as you ride over them.

I was there and saw it more than once

If this is not to be a racer and more of a tourer and around-town affair, does it need to be so close to the ground?

Well the main focus [ now ] is definitively around town/tourer

Is there scope for raising the main frame/lowering the axles?

There is always scope

I have a plan , just need some time to implement it

Paul

 

[stormbird]

A pair of turning circles for a swb and a lwb. They both have the wheels turned the same amount, and the same track plus the swb one takes into account the bottom bracket (yellow box) protruding forward.

See reply to your other questions.

Paul

 

[stormbird]

Why are you so intent on a lwb chassis? It will increase turning circle. I get that most if not all of the pedal cars you see at your races may well use lwb but track requirements prioritise stability at speed

I was not aware 40" wb was lwb ? The pedal car handbook says swb can give twitchy handling [ read I assume @ racing speeds ] however when pushed they can't give a figure for SWB

and you need turning circle as a priority for your road use. I do not understand your choice.

It is not as simple as turning circle IF you are entering a gate that you have to then make a 90' turn ?

So here I start at A and cross 3 lanes of traffic to enter the barriers at B now you can see 1 the tunnel is very very narrow compared with the entrance for B. However it gets worse because with a poor turning circle you have to pass a long way into C before you can turn out of it now to compound the problems this is a single carriageway and so you cannot then swing to the left to get to the left hand side of D because if you do it only makes the turn into D even tighter.

Now this is one of the simpler ones also the tunnels 1 @ 2 can be very narrow maybe as tight as 4ft !

My simple brain assumes that to big a overhang in front of the wheels will mean you have to turn earlier to avoid crashing into the barrier ahead of you ?

If it's just because you want it then that's fair enough. I've done many a thing for that reason myself, but it's at odds with your stated needs.

The rear wheels are considerable further forward than they can be on a tadpole , yes I could bring them further forward to the detriment of the handling I suspect.

To get around the need to hike the layshaft so much for the mech you could run an igh wherever is best between seat and pedals and then run the chain to the layshaft which itself can then be further back as it'll be running a smaller drive cog than the first gear on a cassette. This does suppose you have or are prepared to get a decent igh which I accept is a big budget item.

The plan is to use a wide range cassette say 34T - 10T as opposed to the ubiquitous standard 28T - 14T allowing me to get away with a single ring at the front simplifying the controls and saving some weight.

All is not lost as it is only wood and as Edison said :-
"I have not failed. I've just found 10,000 ways that won't work,"
Luckily not reached 10,000 ways yet

thanks for all your inputs , all food for though...

Paul

 

[Popshot]

My simple brain assumes that to big a overhang in front of the wheels will mean you have to turn earlier to avoid crashing into the barrier ahead of you ?
Paul

The bottom bracket is in the same place on long and short wheelbases so you need to turn both at a similar time. On a swb it isn't the bb that's stuck out but the front wheels that are brought back. That may seem like a play on words but it's not. Both vehicles are the same length. The difference is the swb will turn harder because the pivot of the turning circle is brought nearer the quad.

Think of buses which have large overhangs front and rear and swb to make them more manoeuvrable in tight city streets. If they had wheels at the corners they'd regularly be stuck. The same principle applies here.

 

[stormbird]

So bit more tinkering

few bits are extra as a concession to made from wood and so not strong enough at the joints.

So bit less w/b and more tweaking needed

Nearly there , next up raise seat about 1"- 2" and raise cassette ....

Paul