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

undertoad/popshot

it has changed from that picture there is no jack shaft per-say just a forward pair of sprockets and a rearward pair to route the chain under the seat.
both rear wheels are driven by an expensive and now unobtainiam 2 x freewheel drive unit best part of £400 when you could get them.

two-pulleys-Screenshot-at-2025-01-16-14-52-44.png


I may have discovered a big part of the problem , just need to run a picture past a couple of people before I commit it to here ?

Paul
 
So the chain dropping problem may be linked to this ?
poor-chain-management-DSCF9227.jpg

This is one of the 4 sprockets 2 infront and 2 behind the seat , out of curiosity I tried wrapping a piece of 9 speed chain around it and found out it does not fit ! When I fit another 14 tooth sprocket over it it looks like the valleys are not deep enough forcing the chain to follow a bigger radius than it should do ?

A possible solution would be to weld a sprockets from a normal cassette cluster to this one , like this ?
poor-chain-solution-DSCF9229.jpg


So the inner sprocket is 14T and the bigger outer is 18T

Giving a solution like this:-
poor-chain-solution-with-chain-DSCF9234.jpg

Question is can I weld titanium 14T [ initial sprocket ] to the old 18T ?

answers on a postcard please to the usual address .....

Paul
 
The 14T one is really Titanium?
Regardless, it looks heavily worn, which would be a problem, even if the chain fit.
Even if you could weld titanium, I don't think you could weld it to steel - But what do I know, having never tried to weld titanium......... :unsure:
 
pegasus/DannyC

many thanks for the advice , when I looked into it I decided that I could not even tell if it was titanium and welding was certainly out of the question.....

Sadly after haranguing DannyC for 30 minutes this morning the application of ' more thought ' came up with a different solution ;)

However I am getting ahead of myself ?
cut-line-DSCF9235.jpg

It is impossible to see what is happening due to the body work so set about cutting the rear off and disassemble where possible in a non destructive way as possible. It was not till I started I realised how aero the shape was when you consider it is made out of only 4 basic panels.

Above sides marked for surgery , it was suggested that I make the rear end plug in for racing and a Kammback for bumbling around town , so parts need to be liberated with as little damage as possible ?

back-open-DSCF9237.jpg


Once both sides were cut I could free the turtle deck and we are in business , I had to do this because what I discovered was if you laid it on it's side the chain de-railed anyway due to lack of tension from the rear mech [ not surprising as there are now nearly 3 full chains in it ] and the use of toothed chain guides instead of pulleys with large diameter walls which may have prevented it ?

front-keeper-DSCF9244.jpg


I then made up a crude chain keeper for the front pair of sprockets , purely by accident I got it to big so the space under the chains was big enough for them to de-rail DOH !!

Then I took it for a spin and realised something had happened due to the increase in noise :)

chain-drop-DSCF9245.jpg

This is the rear pair of sprockets the chain still around the sprocket is the drive side chain , however look where the return side of the chain is now ! it was behind the drive side when I set off.

So another keeper was made and the surplus space underneath them was packed out with some cheap plywood screwed to the bracket , quick spin and it stayed on yeah , however venturing further showed it was much to high geared for around where I live.

It appears to be a 10 speed however only 28T - 12T with a 52T ring up front this gives :-
gi-current-setup-Screenshot-at-2025-01-18-17-03-36.png

Now I really need around 20 GI for around here , especially as the pedal car is heavier than the Python.

So next up need to change the front ring maybe 42T or perhaps a 34T would work well , looks like time to get the spares box out for a rummage.

A good afternoons work me thinks especially as it is not really the best weather for working outside , it is approaching 0c again !

Paul
 
pegasus/DannyC

many thanks for the advice , when I looked into it I decided that I could not even tell if it was titanium and welding was certainly out of the question.....

Sadly after haranguing DannyC for 30 minutes this morning the application of ' more thought ' came up with a different solution ;)

However I am getting ahead of myself ?
cut-line-DSCF9235.jpg

It is impossible to see what is happening due to the body work so set about cutting the rear off and disassemble where possible in a non destructive way as possible. It was not till I started I realised how aero the shape was when you consider it is made out of only 4 basic panels.

Above sides marked for surgery , it was suggested that I make the rear end plug in for racing and a Kammback for bumbling around town , so parts need to be liberated with as little damage as possible ?

back-open-DSCF9237.jpg


Once both sides were cut I could free the turtle deck and we are in business , I had to do this because what I discovered was if you laid it on it's side the chain de-railed anyway due to lack of tension from the rear mech [ not surprising as there are now nearly 3 full chains in it ] and the use of toothed chain guides instead of pulleys with large diameter walls which may have prevented it ?

front-keeper-DSCF9244.jpg


I then made up a crude chain keeper for the front pair of sprockets , purely by accident I got it to big so the space under the chains was big enough for them to de-rail DOH !!

Then I took it for a spin and realised something had happened due to the increase in noise :)

chain-drop-DSCF9245.jpg

This is the rear pair of sprockets the chain still around the sprocket is the drive side chain , however look where the return side of the chain is now ! it was behind the drive side when I set off.

So another keeper was made and the surplus space underneath them was packed out with some cheap plywood screwed to the bracket , quick spin and it stayed on yeah , however venturing further showed it was much to high geared for around where I live.

It appears to be a 10 speed however only 28T - 12T with a 52T ring up front this gives :-
gi-current-setup-Screenshot-at-2025-01-18-17-03-36.png

Now I really need around 20 GI for around here , especially as the pedal car is heavier than the Python.

So next up need to change the front ring maybe 42T or perhaps a 34T would work well , looks like time to get the spares box out for a rummage.

A good afternoons work me thinks especially as it is not really the best weather for working outside , it is approaching 0c again !

Paul
Well we don't call this place "Chopzone" for nothing do we? :)
How easy/difficult will it be to swap the front ring out from "Racing Ring" to "Mansfield Ring" Paul?
Can you use a common spider/BCD and just bolt the required ring on and put a clearly identifiable section of chain to be added/removed via quicklinks? I know there are only a limited number of racing weekends.
 
:)
How easy/difficult will it be to swap the front ring out from "Racing Ring" to "Mansfield Ring" Paul?
hard !!! I have either to remove the complete side the ring is on and hope I can reach the back of the other side , or remove side window on that side and work like a gynecologist or try and get the lower front off without disturbing the see through nose ?
All these panels are held with gaffer tape and the odd screw.
Can you use a common spider/BCD and just bolt the required ring on and put a clearly identifiable section of chain to be added/removed via quicklinks? I know there are only a limited number of racing weekends.
Should not need to remove any chain [ although the rear mech is a short cage currently ] as a normal triple is 20 teeth ?
If I leave the current 52T although I may only have power for a 48T it gives me up to 20T less for my hill climbing adventures and just do a hand change before/after race days ?
Thinking a 34T or 36T or at a push a 38T , this will cripple it's top speed however it needs much testing....

Paul
 
So more garage time has been most profitable :)

on-work-trolley-DSCF9249.jpg


Clearing both the garage floor and the work trolley has allowed me single handed to get the car onto the work trolley PROGRESS !!!

on-work-trolley-DSCF9250.jpg
This car is long it over hangs both ends and the wheel base barely fits on the trolley , however now it is very easy to work on most of it.
on-work-trolley-DSCF9253.jpg

Also now I can spin the car around inside the garage , possibly even with the wife's car in the left hand side [ missing from this picture ]
bodywork-frame-250112-n.jpg

So this lies under the coroplast body and I need to be able to remove the body to work on the mechanics , the body panels are gaffer taped to this frame work. While this is nice and light it does make working on the chassis and components rather difficult.
Looking at how many attachment points there are it may actually be easier to make the coroplast parts a free standing body and just bolt it to this frame where it touches ? I think I can reach most of the mechanical parts working around this frame .

So plenty to do however it does not look impossible...

Paul
 
Ok got some more time on the car , mainly deconstructing it hey ho !

So there a few things you never ask a lady ?
Age
Size
weight - well actually I need to know this as moving it around it seems quite heavy and I am the one who has to pedal it ;)
weighing-resized-DSCF9255.jpg


So what am I hoping for ? around 30 kg would be very nice ?
It turns out it is considerably heavier than that @ 33.84 kg , now the reality of this is to get to 30 kg [ ish ] it needs to shed over 10% of it's weight.
I can see that is a very tall order indeed , the whole body may only be that , so where is there to save some weight ?


I do think the seat is very heavy looking at how thick it is , so that needs to come out to be weighed , the problem with replacing it is you get in the car by standing on the seat and then sitting on the seat back before lowering yourself in so the seat has to be very strong and also why the rear of the seat is very strongly supported.[ ie heavy tubing and lots of it ]

back-open-DSCF9237.jpg
So looking at closing the back up ?
new-back-plate-DSCF9258.jpg

This will do , some strong card and the right shape , for the time being I will just cover it in white duct tape and bolt it into place then trim coroplast sides and rear turtle deck to length , that should do for testing and if it meets no rain maybe even a race or two ?
crank-arm-ring-DSCF9261.jpg


I remove the right side window and was able to extract this , so a 4 spoke spider with a 52T chain ring and crank arms cut down to 145mm.
Now I want around 34T-36T however not yet looked in the stash to see if I have any 4 hole and more important do they fit ?

I have some on a triple however that has a square taper not this new stuff ?
So that will mean another BB inside , it would be better if I could fit mine as the crank arms are straight and so have a smaller Q factor.
This may be important IF I decided to make the frame narrower at the front to improve the turning circle ?

Lots to think about Paul
 
I think you could re-design the seat bracing, without losing much strength.
Maybe a shaped thin (2-3mm) steel (or aluminum) strap across the back, and then a single tube brace rearward to each side.

If you're keeping the same one-sided idler arrangement, maybe eliminating the center tube of the "outrigger"?
Being supported in front (where the sprockets are), and attached at the rear, would be enough, I think.
 
Nice pedal car and unusual shape

Can you ride it on the streets or are you restricted to race tracks ?

34kg is not that bad considering 4 wheels, steel frame, coroplast body...

Some fiberglass 3 wheel velomobiles are about 30 kg and body serves as chassis

As you said maybe no need for the secondary frame supporting the coroplast ?

And the axle at the back is it a full rod, transmitting to both wheels ?

For the seat you could make a lighter one using this one as a mould, if you feel up to laminating fiberglass, squeezing out all excess resin
 
I think you could re-design the seat bracing, without losing much strength.
Maybe a shaped thin (2-3mm) steel (or aluminum) strap across the back, and then a single tube brace rearward to each side.
Next thing on the to do list is to remove the seat and then weigh it , maybe just adding one of my polythene ones will save a couple of kilo's ?
If you're keeping the same one-sided idler arrangement, maybe eliminating the center tube of the "outrigger"?
Being supported in front (where the sprockets are), and attached at the rear, would be enough, I think.
I think it will be easier to see what is what once the seat is out , there are certainly more parts on the frame than are needed ?

Paul
 
Nice pedal car and unusual shape
On the face of it quite crude , however it is very aero for only 4 pieces of coroplast (y)
Can you ride it on the streets or are you restricted to race tracks ?
Legally anywhere as it only has pedals.
It is restricted due to it's size [ length and width ] i.e does it fit between the street furniture ? and it's challenging turning circle.
Items I will have to learn to live with or bite the bullet and apply some surgery to....
34kg is not that bad considering 4 wheels, steel frame, coroplast body...

Some fiberglass 3 wheel velomobiles are about 30 kg and body serves as chassis
Well yes and no 34 kg is over 10% more ?
As you said maybe no need for the secondary frame supporting the coroplast ?
It is probably extremely light as it appears to be thin alloy strip , I will re-arrange parts of it so the coroplast can be
bolted to it using nylon bolts then it should be easy to de-cloth it for maintenance.
And the axle at the back is it a full rod, transmitting to both wheels ?
It has a free wheel differential so a ratcheted 2WD.
For the seat you could make a lighter one using this one as a mould, if you feel up to laminating fiberglass, squeezing out all excess resin
I have several quite light polythene seats , comfortable for me with some lumbar support and quite light.
scenic-shot-DSCF8665.jpg

This one complete with Ventist seat pad stopping your back getting sweaty :D
Paul
 
Small update no pictures sorry ....

Got a second chain ring installed after a 25 minute struggle when someone assembled the 4 chain ring bolts with a thread locking compound !
Of course no one owns the special ring driver meant to hold those rings whilst applying the allen key to the other side ;)

Now has a 38T and a 48T , in the 38T it is quite lively and easily climbs the hill on the estate I live on , despite the rear body work flapping in the breeze !

Tried new chain management the keepers sort of worked till I fell fowl of the poor turning circle and tried wheeling it backwards by hand on the rear wheels - failed ! the front chain sprockets keeper rotated to the rear and locked the chain up solid. Now oddly also the return chain then fell off the sprocket at the front despite the keeper - what's that all about then ?

So plenty more to keep me busy , I really ought to have a dead line for the first excursion off my estate ? maybe around/by Friday 31st Jan

Paul
 
So the second shock , after measuring the cars weight is .....
The turning circle :-
turning-circle-DSCF9274.jpg

So cars left front wheel lined up against block in foreground and pedaled in a semi-circle to cross from grass to tarmac and the distance between the outer wheel and the block measured ?
Well I measured my shoe first @ 13" then like a drunk test walked between the two counting 30 steps.
30 x 13" gives 390" or 32.5 ft strewth no wonder I am having difficulty with it on the streets and am scrubbing the front wheels on the body work.
Any attempt at trying to improve this is going to involve a lot of work ?
So I have 2 choices.
1) try and improve the turning circle to make journeys around town easier
2) leave it as is , a race car , and struggle if I try to go anywhere locally

Paul
 
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