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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/24/2011 :  12:28:10  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
Hello All,

This is my first post -- I am not sure if it is appropriate to post this here, but I am not sure where else to turn for help.

I am in the process of building a pedal car in the style of a 1930s Grand Prix car -- it will be 1:2 scale. I have minimal knowledge when it comes to bicycles and trikes. The car is basically a recumbent trike with four wheels. Currently, I am stuck at the drivetrain portion (where I have the least knowledge) and I am not sure where to turn for help. I have a few questions that I hope some of you can help me with.

First, here is a concept drawing of what the car will look like:



As you can see, the driver will be far up front to make the car appear to be mid-engined. When it comes to this project, aesthetics are extremely important; but the car also has to function -- functional art, I suppose.

A run down of things (that I can think of) that should be taken into consideration:

-The car in total (front of body to end of body) will be about 105", give or take a few inches
-The wheelbase is 60"
-Roughly 7 feet from the rear axle to the crank
-145mm crank
-24" wheels, 3" wide rear balloon tires, 2" front
-Two-wheel drive
-7-9 speeds
-The car will hopefully weigh around 80 pounds with the aluminium body and all, but I suspect it might hit close to 90-100

My main concern is whether or not I should be using a mid-drive with the chain being so long. I would like to keep the drivetrain as simple as possible. I came across an older thread on here where someone was concerned about having six feet between the gears and crank; in which there were responses along the lines of "chain length is not an issue as long as you have idlers and chain tubing." I'm wondering if this applies to my car as well.

My other concerns are the actual gearing, how to select them; and how to make the car two-wheel drive. I have seen people on a pedal car forum mention "dual freehubs" from Longstaff, but I can't seem to find anything like that on their site.

I realise these questions are a lot to ask, but any help at all would be very much appreciated; even if someone could just direct me to another person/forum to ask these questions.

Thanks so much.

Mike

purplepeopledesign
recumbent guru

Canada
593 Posts

Posted - 04/24/2011 :  13:30:14  Show Profile  Reply with Quote
Will you be racing this pedal car? If so, bear in mind that duplicating the forward seating position of an old Auto Union will put too little weight distribution on the rear wheels, giving you problems with rear wheel traction and oversteer.

Overall chain length is quite high so you're probably going to need some combination of mid-drive and/or idlers to keep the chain from banging around. A mid drive will make it easier to get a large range of gear ratios without getting into extreme chain ring sizes. A mid drive is also a great place to split the driveline for each rear wheel.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/24/2011 :  13:44:31  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
No, I will not be racing this -- I just want to be able to drive this on bike trails somewhat comfortably. I realise the seating position is not ideal for maximum performance, but it must look this way.

It sounds as if I should use a mid-drive, then. Something like a mountain bike hub with a cog welded on each side?
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Jeff Wills
human power supergeek

USA
1214 Posts

Posted - 04/24/2011 :  16:59:50  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
I would guess that you're building something like a Utah Trikes Quad: http://www.utahtrikes.com/TRIKE-UTCQUAD.html

You could do something similar starting with a cheaper recumbent trike and a bicycle-to-trike conversion kit: http://cgi.ebay.com/Bicycle-Bike-Tricycle-Trike-Conversion-Kit-Chrome-/230470203528

Bear in mind that a four-wheeler will need to flex a bit to remain in contact with the road. If it's too stiff, you could end up with one tire hanging in mid-air. If that's your only driving wheel (i.e. a real differential) you'd be going nowhere. A "dual freewheel" usually means there's a "normal" bike hub mounted as a mid-drive, with two chains driving each half of the rear axle separately through freewheels. This allows some differential action without the expense of a true differential.

Feel free to post questions here. I've been around bicycles, especially odd bicycles, for 30 years. There's not much that hasn't already been tried.

Your project sounds interesting, and it'll certainly end up cheaper than an original Auto Union Grand Prix racer!

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/24/2011 :  17:50:26  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
Thanks, Jeff. The Utah Trikes Quad is very similar to what I am building.

Right now, I already have built a frame from scratch, so buying an existing trike is out of the question. However, I have considered the trike conversion kit before. Correct me if I am wrong, but the kit in the auction appears to only be 1WD? If not, maybe welding that to my frame is the way to go.

As for the "dual freehub", this is the Longstaff setup I am referring to, which has one freehub (I think?) connected to two halfshalfs:

It's all a bit confusing to me to be honest, but it is slowly sinking in!
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/25/2011 :  21:23:34  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
I have decided to have two halfshafts machined to fit wheels and freehubs, which will go to a mid-drive. The mid-drive will be a bicycle hub with a sprocket mounted to each hub flange (for the left and right axle freehubs); with a multi-speed cassette on the right side of the hub.

This leads to a few more questions:

1 - How should I determine where to place the mid-drive in relation to the rear axle and crank?

2 - How do I go about selecting the gearing for the freewheels; mid-drive sprockets; cassette and chainwheel? Is this mostly determined by trial and error? Where should I begin?


Edited by - King Ankylosaurus on 04/25/2011 21:24:36
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Jeff Wills
human power supergeek

USA
1214 Posts

Posted - 04/25/2011 :  21:29:20  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
quote:
Originally posted by King Ankylosaurus

Thanks, Jeff. The Utah Trikes Quad is very similar to what I am building.

Right now, I already have built a frame from scratch, so buying an existing trike is out of the question. However, I have considered the trike conversion kit before. Correct me if I am wrong, but the kit in the auction appears to only be 1WD? If not, maybe welding that to my frame is the way to go.

As for the "dual freehub", this is the Longstaff setup I am referring to, which has one freehub (I think?) connected to two halfshalfs:

It's all a bit confusing to me to be honest, but it is slowly sinking in!




Hmmm... I'm not sure the axle in that picture has any differential at all! I would guess that it's a straight, one-piece axle since I don't see any sort of mechanism for allowing the rear wheels to turn independently. Certainly simple, but it'll make the machine a bear to turn.

Yes, the trike conversion kit is 1WD. As I said, the cheap ones will be. It's only when you get to the very-high-end stuff like the Utah Trikes and Hase Kettweisel part that you find two-wheel-drive with differentials.

I'm pretty sure the Hase trikes use a differential unit made by Samagaga: http://www.samagaga.com/Category.aspx?Category=DG72 . I think Hostel Shoppe would be able to give you more details on what's involved since they're a Hase dealer.

I've been looking around for a picture of the dual-freewheel type of rear axle- it's easier to show you a picture than to try to describe it. Haven't found anything good yet.

__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/25/2011 :  22:39:03  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
The Samagaga differential looks very nice! When searching for prices, I came across other recumbent forums where people were discussing using go kart differentials for their trikes.

http://www.staton-inc.com/store/products/Differential_3_4_x_38_inch_794652-184-0.html

What do you think of this? The Samagaga differential is apparently around $300 (I will email them to be sure) which is out of my budget. The go kart diffs are half the price or less.
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/26/2011 :  00:36:00  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
Good thing I did contact Samagaga -- their differentials range from $61-81 USD. Not bad at all!
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25hz
human power supergeek

Canada
1223 Posts

Posted - 04/26/2011 :  07:49:17  Show Profile  Visit 25hz's Homepage  Reply with Quote
Looks like you're well into the fabrication and decision-making process already.

Your car is going to be big and heavy. Any place you can save weight and cost and drag, is going to be a good thing - whether you are racing it or not. I have some experience with mid drives and mid-idlers, etc etc, and if you can avoid them, avoid them. They are more weight, more cost, more complexity and most importantly, will add more drag, whether you "do them right" or not. Try some small idlers and chain tubes to help with chain management. You can always add the idlers later if you absolutely need to. A 7' long chain is long, but it's not exceedingly so in the world of recumbents.

You can make a simple, and effective differential yourself, no fancy custom machining, using nothign more than standard bike parts.
- use two half shafts like you're doing now, and put a single sprocket BMX freewheel on the end of each half shaft.
- take any multi-speed hub (a disc brake hub is easiest) and attach a sprocket to the disc brake mounting side, and have the inside sprocket on the cassette with the same tooth count. The rest of the cassette sprockets can be whatever setup you want.
- mount the rear wheel hub in front of the jack shafts, far enough ahead of them to maintain clearance between the cassette gears and the jackshafts
- how it works, is when you pedal, the chain drives the rear hub, just like normal. The the sprocket on the disc side is connected to the left jackshaft with a short section of chain. The cassette sprocket that is the same tooth count as the disc brake side sprocket, is connected to the right jackshaft with another short section of chain. The rear hub is mounted on slots so it can be adjusted fore and aft to apply chain tension to the short jackshaft chains.

In the end, you have a posi-track drive line that also has a built in slip differential. Nothing fancy, nothing expensive. As you corner the slowest wheel automatically gets the drive while the fastest wheel freewheels. Also a very effective traction aide. Another option is you can hook the sprockets directly to the spoke flanges using small AL adapters instead of using one of the cassettes and the disc bolts.

These boys do quads all the time.
http://www.pedalcars.info/
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Speedy
recumbent guru

USA
762 Posts

Posted - 04/26/2011 :  08:20:29  Show Profile  Reply with Quote
examples of a BMX freewheel type differential can be seen here :

https://picasaweb.google.com/111289919904122427931/MountainQuadPics#
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/26/2011 :  10:56:26  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
25hz, that's a lot of great information. I've actually been to your site, which has been one of my main sources for information.

Do you think it would be lighter to just use the Samagaga differential (which will accept a multi-speed freewheel), with one chain in total? It will definitely be cheaper, but will there be a downside to the performance by doing it this way?

Also, Speedy -- that is a really awesome quad! A very clean design. Who makes those?

Edit: I found the site. It is now out of production.

Edited by - King Ankylosaurus on 04/26/2011 11:03:15
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Speedy
recumbent guru

USA
762 Posts

Posted - 04/26/2011 :  12:03:19  Show Profile  Reply with Quote
the mountain quad frame was made in my shop as a sub-contract
just recently cleaned out the last of the tooling and spare parts
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/27/2011 :  13:44:17  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
It looks like shipping from Taiwan for the Samagaga differentials will cost about $125-$200, depending on how quickly you want it. That seems insane to me. I am going to use the setup that 25hz mentioned earlier.

As for the BMX freewheels, does it matter how many teeth are on them considering the hub sprockets will have the same amount?

Edited by - King Ankylosaurus on 04/27/2011 13:45:27
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Speedy
recumbent guru

USA
762 Posts

Posted - 04/29/2011 :  06:06:27  Show Profile  Reply with Quote
it's common practice to drive one wheel and the opposite to coast on bearings
off the self parts are low cost from the following company ~ products
hubs, axles, bearings, sprockets, adapters etc.

http://www.rhoadescar.com/

http://www.sunbicycles.com/products.php?cl1=RECUMBENT

the Sun bicycle parts are at : http://www.jbimporters.com/web/
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/29/2011 :  10:44:23  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
Thanks for the links. I am definitely sticking with a 2WD setup, though. Because of how heavy and big the car will be, I think I will need all of the traction that I can get.

I am wondering if the tooth choice for the rear freewheels and sprockets matter much, and if so; can anyone recommend what I should try?
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Larry Lem
human power expert

South Sandwich Islands
2326 Posts

Posted - 04/29/2011 :  14:11:35  Show Profile  Reply with Quote
Big and heavy do not dictate whether single-wheel drive would be unacceptable. It depends on whether you think you'll be cornering hard enough to lift an inside, driven-wheel. Have you ridden an adult, upright, tricycle with single-wheel drive, like a Workman Cycle?

Larry Lem
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King Ankylosaurus
Starting Member

USA
10 Posts

Posted - 04/29/2011 :  16:59:31  Show Profile  Visit King Ankylosaurus's Homepage  Reply with Quote
Larry, I have not. Something I meant to mention along with the weight and size, is that I will be sitting very far towards the front -- other pedal car builders have told me that 2WD is probably the best way to go. While I do not doubt what you said is true, I am not exactly sure how far I will be pushing this car -- I would like the car to be able to adapt to most situations.

Edit: I do have a cheaper 1WD pedal car which is much smaller than the car I am building (based off of a Rhoades car, I believe), and the 1WD is most certainly an issue with cornering and loss of traction. Based on my experiences with that car, I think it would be best to make this car 2WD.

Edited by - King Ankylosaurus on 04/29/2011 17:02:34
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teubner
recumbent guru

785 Posts

Posted - 04/29/2011 :  20:26:25  Show Profile  Reply with Quote
Use this front drive in the back?
http://www.sidewindercycle.com/
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MaxBeer
Starting Member

Italy
1 Posts

Posted - 05/31/2012 :  04:50:44  Show Profile  Reply with Quote
Hello.

Itěs possible to have more photo of King's pedal car?
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Steven Challenge
recumbent enthusiast

Netherlands
142 Posts

Posted - 05/31/2012 :  07:50:38  Show Profile  Reply with Quote
It's been a year ago, but Maxbeer has revived it. I wonder if King has finished the quad. If not (and for others who want to make a quad) http://www.atomiczombie.com/ has got quite a few recumbent 2, 3 and 4 wheelers, complete with plans.
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harv
recumbent enthusiast

340 Posts

Posted - 06/01/2012 :  05:23:38  Show Profile  Reply with Quote
Looks like Greenspeed has added a quad version of the Anura to their product mix. http://tinyurl.com/c8bax5x
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Steven Challenge
recumbent enthusiast

Netherlands
142 Posts

Posted - 06/04/2012 :  07:29:01  Show Profile  Reply with Quote
If I had the time, space and $$$ I would like to make a dual seated quadcycle with Ford model-T hotrod appearance. Problem with a 2 seater is that you need 2 people to make it work properly. Unless you make it E-power assisted.
For an easy way to create a 4 wheeler, exchange the rear wheel from a regular recumbent trike with a trike back. Like the Utah Trikes Quad as mentioned before. I don't know if making a full fairing in a car shape would be practical. I would go for a self supporting chassis in a car shape with quadcycle components added. More like trying to turn a car into a quadcycle than trying to turn a quadcycle into a car.
Since the quad wouldn't be made for high speed, but more for cruising, I would use 20" 3" tires. With only front suspension, just to keep all wheels on the ground when going of and on sidewalks. Low gears for more power.
It would be a recumbent but it wouldn't be what a recumbent stands for: speed, low weight, airodynamic. It would be more of a cruiser bike that happens to be 4 wheeled and recumbent seats.
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Grant-53
New Member

USA
70 Posts

Posted - 06/14/2012 :  20:21:48  Show Profile  Reply with Quote
At some point a shaft drive may be desireable. A Model T would have a higher drag coefficient than a Formula car because of the flat front radiator. Chat with some garden tractor or ATV folks about what they use for differentials.
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Grant-53
New Member

USA
70 Posts

Posted - 06/14/2012 :  20:58:59  Show Profile  Reply with Quote
As for driveline position the ease of access is a key consideration. Ratios from 25 to 75 gear inches would work for cruising. Most cassettes have 28T as the largest gear and 11T as the smallest. Smaller gears have less weight but may wear faster. A mid line gear transfer need only be a pillow block bearing, a short tube, and two sprockets attached with set screws.
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Steven Challenge
recumbent enthusiast

Netherlands
142 Posts

Posted - 06/19/2012 :  00:38:44  Show Profile  Reply with Quote
Talking about gears and alternative drive, has anyone ever seen something like this:
http://www.stringbike.com/
It might be interesting to replace a long chain with this. I've seen on youtube the working model of this, with some explaination of how it works.
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