Quad Pedal Car - 2025 late Xmas/early Birthday present ?

[undertoad]

I'm trying to imagine the circle your heels make, around that bottom bracket, and whether the rear support and cross member for said support, could be shortened, and moved forward, respectively.
This would bring it closer to the kingpins, and thus lessen the frame twist there, thereby enabling you to widen them.......... Maybe
Perhaps there's enough ground clearance to make a slightly dropped cross member there.
Like I said, though, all just in my (fevered) imagination

 

[Trickytrike]

Thanks great post I was contemplating building a quad too but thinkink perimeter frame was an issue. So it works "thanks to" poor turning radius, the wheels are close to the frame to limit twisting forces.

You are brave to take this on so you are likely to rebuild it from the ground up...

 

[stormbird]

Well I am not sure where the idea of the wheel placement twisting the frame originated ?

Having driven it very little i cannot say ' it does twist ' or ' it doesn't twist ' , I am not even sure what the characteristics would be if it did twist ?

90% of the current pedal cars racing have peripheral frames of varying designs.

It does not have a ' poor turning radius ' IF you plan to use it as a pedal car , it finished a 6hr race !

I do not want a quad that only leaves my drive for races , it seems such a shame it languishing in a bike shed, and these cars deteriorate faster if they are not used.
So I put some street tyres on it and will have a stab at increasing it's turning ability whilst shortening it a tad , with the body on it is very long making it hard to manouver in and out of the garage onto the work trolley etc etc. These things seems to swell up in size when put into small spaces

It looks a little like a ground up rebuild , I see it more as a detailed winter service , there were many hours spent getting the car to this level of competitiveness that is what I bought I hope it will turn out to be usable around my home.

At the end of the day though we must be sat in it on a race grid on the 6th of April

Paul

 

[stormbird]

I'm trying to imagine the circle your heels make, around that bottom bracket, and whether the rear support and cross member for said support, could be shortened, and moved forward, respectively.

There is a some aspects I maybe would have done slightly differently that now are not worth the effort involved to alter

This would bring it closer to the kingpins, and thus lessen the frame twist there, thereby enabling you to widen them.......... Maybe
Perhaps there's enough ground clearance to make a slightly dropped cross member there.

Pedal/BB height is dependent on a couple of things not immediately obvious ?
Length of cranks - these are 145mm
Size of shoes - mine are a UK 10 - I drove a Oddballs pedal car where the driver had size 13 shoes !!!
whether there is a need for bodywork under the foot.
One [ or more ] of the Royce pedal cars if you held your foot vertically the heal scraped on the ground ! now this is fine on a car with no floor however means if you then add a floor your heal constantly drags along it.

Like I said, though, all just in my (fevered) imagination

I have one to !

I was trying my own design a while ago and this was the mock up for a centre spine quad :-

Now on the face of it , it looked like it may have worked however whist the front was ok ish the rear really needs to be radically different as there is no where to attach any of the hardware to drive the rear wheels ?

It started as a Delta design and morphed into a Quad Page 5 onwards , another 6 pages !

Paul

 

[stormbird]

A little bit of progress made ? so lets share it.

Having the car almost completely stripped I have discovered a couple of things not quite right with it ?
The one I have investigated and found a solution for was one of the half-shafts stuck when going around and took some effort to move past a certain point.

It was apparent it stuck in the same place and when giving it a good looking at I discovered this . can you see the bright crescent below the 54611 number.
The cause of this is the silver grub screw just above and to the left , I think the bearings only came with a single grub screw [ that is black ] and some one drilled and tapped for a second one , however the black grub screw is flush with the collar and the silver one is obvious much to long.
Easily fixed , and the other one will be treated the same.

I think I reported the seat is from a race car and in recumbent terms quite heavy [ 2.2 kg ], I tried and failed to get a couple of Windcheetah seats from the BHPC club , one was free however a 300 mile round trip and he could not post. The other the owner was some what taken aback when I mentioned I was going to cut off the neck/head rest part, now I had originally asked for a seat need some repairs not one good enough to use.

idly moving one of my polythene seats [ 0.97 kg ] around I dropped it onto the race car seat and they were quite similar ?

So I made a pattern on some wall paper and taped it to the back ..

I then proceeded to to cut the seat out to the pattern and drill some mounting holes in it.

I have not yet taken a picture of it , however it seems to have worked ! I now have a seat that is 1.32 kg almost 1 kg lighter a worth while saving. The seat is slightly more flexible than the polythene one it may need a little more work to make it usable in a race environment.

Now before you say ' use your polyethylene ' you numpty , I only have 3 , 2 of which are in use and I don't want to mount one in the car and then have to sell it with the car.


Paul

 

[undertoad]

When in doubt, saw it out - A most excellent tactic on the seat
That is, as long as you don't have to re-mount it with excessive extra framing

And that screw had to be costing watts, with each revolution - Little things like that will add up........

 

[Trickytrike]

Good diet for the quad !
normal grub screws have no "head" and mount with an hex key is it ? Well spotted.

 

[stormbird]

Good diet for the quad !

Got to weld something in soon !

normal grub screws have no "head" and mount with an hex key is it ? Well spotted.

Nah these have one of those fancy screw heads T20 I suspect , they are all over the car however mixed up with hex keys and my eyes cannot distinguish between the two !

Paul

 

[DannyC]

Getting along very well there Paul.

 

[stormbird]

..and relax !
So I was able to line up the left hand joint quite well after a little hand fettling , however it proved impossible to line up the right joint at the same time ?

The reason being the slight taper on the chassis side rails meant the back was to wide and the front to narrow they were out by about 4mm , I though the best plan was to try and cold set both ends. Now the rear was a doddle because there was no cross member it just took a big ratchet strap and I could pull it in far enough that when it sprung back it had moved 2mm. The front however was extremely hard as using blocks of wood and a car scissor jack I attempted to spring them apart , without one of the blocks of wood flying out into my face. It seemed any attempt to line them up caused the other side to come apart. The only solution was to weld up the left and hope the right was a good enough fit to also be welded up ?

Well looky here we have a chassis back in one piece , now on the bench I first welded the top joint then with some trepidation did a upward weld on both the side joints and it worked ! It now has a w/b of 44" instead of 50".
The ground clearance is now 3" , that should help on the street , the pulleys now want a mount making and add where the underside of those is also 3" off the ground...

With the cut down car seat in roughly the right place it should look like this.
I have yet to turn it over and have a look at the underneath , if I can I will also weld those joints up.

Even if I can I am going to cap it with a strip about 3" long running under the joint and coming up the sides , in-case I failed to get adequate penetration on those welds..
Also I discussed with DannyC whether to put a vertical web across the joint in the centre of the tube to resist compression ? jury's out so far on that idea.

So tomorrow cap the underside and also weld up to pieces to tie the ends of the curves pieces to the main frame then I can see where the seat needs to be and see if I can get away with only 2 pulleys under the seat and not 4 ?

Paul

 

[stormbird]

Sadly the underside joints were not as neat :-

However the gap on the right one is small enough to TIG/fill and once cleaned up will be capped over with some 3mm plate so good to go.

Other issues however have been found :-

This cross-member a just behind the steering allows you to get into the car without stepping on the steering connecting rod , however it is bent.
So was it bent when made or has stepping on it bent it ? Need to ask.

Update - deliberate apparently - phew one less thing to fix...

So how do I get the rear mech off ? if I need to ?
Looks like the best bet is to make a custom tool , piece of 3mm plate with a 5mm hex key welded to it.
Possibly less satisfactory is to drill a hole all the way through the tube on the left - hmm I can see that lining up NOT !

These were touted on the pedal car forum as a solution to the chain management , they are VERY small !!!
Only 36mm diameter with a 27mm trough in them.
Now they are used on the outside of cars which have a 3 chain drive just to stop the chain skipping off the drive sprockets .

This car has one visible here at the front and one hidden behind the rear wheel below the sprocket.
However I need them to divert the power and return side of the chain under the seat , a tough job they may not last !

So lots still to do.

Paul

 

[undertoad]

Hard to tell from the photo, but it looks like the derailleur has barely enough room to move !

Maybe just saw off a suitable hex wrench short, and see if it will fit ?
If you make a tool, drill through the handle, and weld the wrench stub from the back side, so the front is flush.
But you probably figured that out already.

 

[stormbird]

Hard to tell from the photo, but it looks like the derailleur has barely enough room to move !

The car is upside down so it stretches upwards to work.

Maybe just saw off a suitable hex wrench short, and see if it will fit ?
If you make a tool, drill through the handle, and weld the wrench stub from the back side, so the front is flush.

Yes same idea contemplated with DannyC this morning , we both came to the conclusion it would work to remove it. However we both have had lots of difficulty getting the fine threads to engage when we have plenty of room and the right tools ? no idea if would be possible with the homemade tool and no space to work.

But you probably figured that out already.

Yes we had , was struggling to think why I had not come across this on the other pedal car then it dawned on me it had a bolt on bracket , so you could fit the mech first then screw the bracket on. On the to do list IF I find I need to increase the gearing by changing the rear cassette.

Next up seat and chain management , I hope.

Paul

 

[Popshot]

There's not a lot of sideways support on that seat now. A racing corner could have you relying on the bars.

 

[stormbird]

There's not a lot of sideways support on that seat now. A racing corner could have you relying on the bars.

Once the seat position is found I need to add something like this :-

Only now with my new svelte seat it can be a little less wide at the top and I hope made from tubing a little lighter ?

Paul

 

[stormbird]

Wanted to take advantage of a nice day and got about 2.5 hours on the car , welded up and plated the underside of the joints.
Added a stay to each of the steering lever mounts where I had abruptly saw them off [ to save weight you know ].
All this wants cleaning up when I next drag it outside for a good talking to.

Looking for a front roller position that will work with just one pair of rollers instead of one in-front and one behind the seat mount:-

This board the rollers sit on represents my ground clearance , just up the top of the picture slightly off centre you can see the chassis rail and a vertical piece of wood , that is 3" from the floor. So I figured if I put a fake new floor in 3" off the real floor I can play around with the roller position and the lower seat mount and know I won't reduce the minuscule ground gap.

Currently propping the mech vertical with a lump of wood to see where the chain run will be , I need to get a index shifter on the mech then I can dispense with the wood and get the chain onto the biggest ring currently only a 28T [ there is a 32T - 11T waiting to be fitted , another saga if I get that far ]

This strange beast lives near the chain ring , unsure whether I now need it , I certainly seemed to have initially threaded it the wrong way ' Must try harder '

Overall view where there appears to be 4 chains , still a work in progress

Paul

 

[undertoad]

This strange beast lives near the chain ring

I know it can't be so, but in that photo, it looks like the chain is sawing its way through that cross member
I'm sure you can come up with some lighter bracing than that "X" member behind the seat -
Just 2 angled braces, tied together at the seat back, would likely be solid enough.

 

[stormbird]

I know it can't be so, but in that photo, it looks like the chain is sawing its way through that cross member

Looking back at the pictures I took when I first got it I got the chain the wrong side of it , I am hoping now I don't need it.
We shall see.

I'm sure you can come up with some lighter bracing than that "X" member behind the seat -

Just 2 angled braces, tied together at the seat back, would likely be solid enough.

I can see why it was done like that as it becomes very rigid , needed because of the body work for access you have to sit on the top of the seat back to get in to the seat.
However the voice on one shoulder is saying yikes taking up most of the luggage area ! then the voice on the other shoulder shouts even louder IT'S A RACING CAR , IT DON'T CARRY LUGGAGE !!!

Paul

 

[Dale Rider]

Some of the pedal cars are based on tadpole trikes , not in itself bad , however it does dictate the shape of the car :-

It means the pedals are way out front and to stop the cars being unacceptably long they tend to have a short w/b. This also makes body work harder to add.
My car was 7.5 ft I hope to get it down to a more manageable 6.5 ft [ or less ]
There is a length limit in the rules raised to 2 meter to let Quatro Velomobiles enter , I doubt if anyone with one of those would be mad enough

The 2 teams currently running the most cars : -
Apollo - peripheral frame single tubes
Royce - peripheral frame complicated space frame


Paul

The rule is 3 metres. Hope you haven't chopped it down yet!

British Federation of Pedal Car Racing
British Pedal Car Specification Issue 7 (2024)

3. Dimensions
3.1. Maximum overall length: 3000mm
3.2. Maximum overall width: 1125mm

 

[stormbird]

The rule is 3 metres. Hope you haven't chopped it down yet!

That boat has long sailed

Paul