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jdblessing
04-02-2016, 03:57 AM
Okay, here I am with another design question, as per the title of this post. I've noticed that racing wheelchairs have the big wheels set at an angle yet the trike designs here have the wheels all perpendicular to the ground. Has anyone looked at the reasons behind the geometry of the wheelchair wheel tilt? It's not just for grip--even the hand-pedaled chairs have the "A" frame design. I'm guessing it may help reduce lateral stress on the wheels during turns. Any thoughts if this could be beneficial for AZ trike design?

gir.
04-02-2016, 04:11 AM
I haven't built mine yet, but I'm planning on adding some slight camber to mine as well. A couple degrees on the negative side. May slightly increase tire wear, but I'll trade that for improved cornering. Hopefully one of the experts here can chime in for any additional reasons.

ken will
04-02-2016, 07:36 AM
Racing wheelchair wheels are angled 10-15 degrees for a more efficient pushing and pulling angle, and to keep from hitting the fenders with the upper arms.
http://www.handcycleracing.com/hawaii2005.jpg

stormbird
04-02-2016, 09:16 AM
Oh myth busting time

The camber is not for road holding or stability.

Most deltas have the rear wheels 30" - 34" wide to stop them tipping over on corners.

If a wheel chair is to go fast it also needs this track width , if the wheels were not canted in you could not comfortably reach the tops of the wheels to power them.

Some trikes [ i.e Hasa Kettwiesel ] have canted rear wheels this is a mechanical thing as it puts the axle pointing down under the seat this allows the cassette to be low enough so there are no idlers in the drive system.

The stability of a trike comes from keeping the vertical cg within the triangle between the 2 rear wheels and the front wheel.

The only way to make this triangle bigger is to increase the track and not camber the rear wheels.

Tom Schneide
04-02-2016, 10:34 AM
You can increase the stability triangle slightly, formed by the 3 tire contact points, by negative camber on the rear wheels and a longer wheelbase on a delta. But as stormbird says, it is much easier with a track width increase. Also keep the weight (rider) low and close to the rear wheels to improve stability and not rolling over.

swizz69
04-02-2016, 12:13 PM
Negative camber on the rear wheels has the effect of widening the track (the tyre contact points are further apart) without increasing the physical width of the trike.

You can thank Stormbird for that nugget of wisdom as he explained it to me - you get the wide track for better cornering along with narrow width to get through some of our dreadful barriers on UK cycle paths ;)

A downside on a delta is that should you want 2 wheel drive, it'll be a bit more complicated!

gir.
04-02-2016, 02:48 PM
You can increase the stability triangle slightly, formed by the 3 tire contact points, by negative camber on the rear wheels and a longer wheelbase on a delta. But as stormbird says, it is much easier with a track width increase. Also keep the weight (rider) low and close to the rear wheels to improve stability and not rolling over.


Oh myth busting time

The camber is not for road holding or stability.

Most deltas have the rear wheels 30" - 34" wide to stop them tipping over on corners.

If a wheel chair is to go fast it also needs this track width , if the wheels were not canted in you could not comfortably reach the tops of the wheels to power them.

Some trikes [ i.e Hasa Kettwiesel ] have canted rear wheels this is a mechanical thing as it puts the axle pointing down under the seat this allows the cassette to be low enough so there are no idlers in the drive system.

The stability of a trike comes from keeping the vertical cg within the triangle between the 2 rear wheels and the front wheel.

The only way to make this triangle bigger is to increase the track and not camber the rear wheels.
I'm building a tadpole, would this be the same? I'm thinking moreso for the high speed downhill, that the camber would help. I know about the stability triangle (drive fork and clamp trucks), and my seat is going to be extremely low. Best trying to gain as much advantage as I can without widening the track so much (want to fit in narrow bike lanes).

jdblessing
04-02-2016, 03:13 PM
Thanks for the information, folks! I appreciate the opportunity to ask without being made to feel foolish for asking. :)

stormbird
04-02-2016, 05:03 PM
I'm building a tadpole, would this be the same? I'm thinking more so for the high speed downhill, that the camber would help.

If you read the above it does say the camber plays no part in stability/road holding only allows a wide foot print at the contact point width less width at the top of the wheel.

Well I cannot comment on tadpoles as I don't build them however as the steering needs to be centre point , zero scrub , ackerman and all that entails I would say don't add camber.

If in doubt a good rule of thumb is do you see it on commercial offerings ?

All the trikes I know of have vertical front wheels I think a couple of velomobiles have camber on front wheels again it gives them a wide track and also allows the top of the wheel to hide from the airflow inside the body work reducing drag , not a consideration for a trike.

if you can implement it properly the only way to increase stability/road holding for a given track width [ both tadpole & delta ] is to have the wheels tilt that gives the trike a cornering ability very similar to a bike.

Don't confuse tilting with lean steer they are not the same and behave differently when ridden.

gir.
04-02-2016, 06:28 PM
If you read the above it does say the camber plays no part in stability/road holding only allows a wide foot print at the contact point width less width at the top of the wheel.

Well I cannot comment on tadpoles as I don't build them however as the steering needs to be centre point , zero scrub , ackerman and all that entails I would say don't add camber.

If in doubt a good rule of thumb is do you see it on commercial offerings ?

All the trikes I know of have vertical front wheels I think a couple of velomobiles have camber on front wheels again it gives them a wide track and also allows the top of the wheel to hide from the airflow inside the body work reducing drag , not a consideration for a trike.

if you can implement it properly the only way to increase stability/road holding for a given track width [ both tadpole & delta ] is to have the wheels tilt that gives the trike a cornering ability very similar to a bike.

Don't confuse tilting with lean steer they are not the same and behave differently when ridden.
Very good info, thanks. I thought that I'd seen one or two that had slight camber, but I'll go and do more extensive research again. Thank you!

LongRider
04-03-2016, 03:36 AM
As an aside, adding camber will increase wear on your tires -- most all are not designed to be ridden at a slight angle...

stormbird
04-03-2016, 03:52 AM
jdblessing & gir

Not sure where you are both coming from

ie. experience in welding - workshop - mechanic skills etc

or your riding conditions ie commuting - leisure - touring etc [ ever ridden a trike before ?]

So it is hard to say do this or that , however there a couple of general rules which may help.

a) if you buy some plans [ both tadpole and delta ] or get them from the net [ there are some free ones ] you can assess how hard it will be to build ? add up all the joints which has the least ? which it is easiest to get the bike parts for ie hard finding 15mm BXM wheels

b) consider the first build a taster for building and riding and that YOU will build a second and may go on to build many more

c) in-light of b) don't try and make the first one perfection just make it fit you [ e.g don't struggle to make every thing adjustable ] and safe to ride , the second one can incorporate all the things you thought of whilst building the first and can be made to a higher standard whilst you still have one to ride.

d) all plans can be followed or changed ! can't find good 26" wheel for the back then use 24" or 20" for the first one , you need lower gears anyway than you find on a road bike.

e) enjoy it !!! it's meant to be fun

A few types and pros and Cons

Tadpole

pros - more common - usually corner better [ at a faster speed ] than a delta [ as generally ] they are a lot lower.

cons - difficult to make steering [ getting angles right ] and fabricating kingpins - hard to make FWD or leaning

Delta

pros - steering easier to make - generally better load carriers as lot's space behind seat - can be FWD very easy - can be a leaner easily

cons - harder than tadpole to drive rear wheel - most are design higher than tadpole to make easier to get on/off at expense of cornering ability

your choice

jdblessing
04-04-2016, 12:14 PM
As for me, I have a complete and total absence of welding experience at this point. I am aware that my ambitions are sometimes much bigger than my abilities, too. I have bought several plans from AZ so far. While the deltas have a more complicated back end frame and they indicate making our own rear hubs, the tadpoles have the hassle of getting the front head tube angles down as well as the various steering methods to chose from. Just trying to figure out which one would be a better fit cost-wise and skill-wise for a beginner like myself is a bit baffling. Square tubing of the recommended dimensions/material is difficult to hunt down locally. I've managed to gather together about 14 or 15 old bikes (all of them steel frames), mostly 20" wheels but a couple have 26". Area out here is rather flat although I'd like to participate in the BP MS 150 with a recumbent trike sometime in the near future. The BP MS 150, btw, is a 2-day charity ride--benefiting Multiple Sclerosis research--going from Houston to Austin TX, about 150 miles, which is why it's called the "150." I tried years ago to go the distance, but I was on a regular upright bike and I only made it half-way. Someone at the finish line made me feel bad for not completing the ride, so I want to at least make it all the way next time. Figured a recumbent trike would help with the speed and going up the hills. Plus, it'd be fun to ride around the neighborhood. I'd eventually make a second one for my wife who had never been taught to ride a bike.

MrIdaho
04-04-2016, 02:32 PM
if making hubs scares you then look at building a "Merdian" style trike. Two rear wheels and one front wheel but using non altered wheels, one front and one rear wheel of same size mounted within a boxed frame so you have 4 dropouts in the rear then the front fork in the front. All you need is to build say a streeftfox or other delta style, add two more frame sections for additional dropouts to mount your rear wheels. Add a jack-shaft with 3 pillow block bearings to drive the left rear wheel ( the gear cluster is mounted on the left rear to be able to connect the drive chain. For jack-shaft sprockets use #40 or #41 sprockets but grind them down to fit the narrow bike chain. This is my next planned project after I finish up the 2nd Warrior Junior for my two grandsons.
Going to add a front and rear suspension for additional challenge.
Using 20" rear wheels will aid in going up the hills.
If you wanted to add some additional gearing then freewheel adapters are needed.
As for welding, either take a night school class or contact a local welding shop.
Good Luck

Twinkle
04-04-2016, 03:30 PM
Take a look at a different approach with the "outboard discs " thread how I converted a tadpole to a quad using relatively easy to make bits and a simplified rear end .
it works ok for us on the quad tandem ( quadem project )

and the "locust 2015" project a basic tadpole using parts salvaged from a kids gate and a couple of bike frames - more work but less money .

It can be done

regards emma

stormbird
04-04-2016, 06:04 PM
As for me, I have a complete and total absence of welding experience at this point.

Do you intend to get a welder and learn ? or farm out your welding to someone else , no one on here will dis you for farming it out and it may be the quickest way for you to get your first trike rolling.




I am aware that my ambitions are sometimes much bigger than my abilities, too.

We all gotta dream and no one on here was born knowing how to weld [ ok well maybe Twinkle ]


I have bought several plans from AZ so far.

Good start.


While the deltas have a more complicated back end frame and they indicate making our own rear hubs

This forum is NOT only about Brads stuff others have altered his plans or build non Zombie machines , so is this simple enough ?

http://www.spiritofbalaton.hu/articles.php?article_id=75

it is a Delta called a Python however as it is front wheel drive there is no complicated rear wheel drive and not built up hubs/wheels the rear uses front bike forks and any size wheels you fancy.
Could easily be built with the frame from a large trampoline instead of square tubing , however round is harder to work with for a beginner

my build thread is here for a similar trike :-

http://forum.atomiczombie.com/showthread.php/8210-Building-a-python-trike?highlight=

and there are lots of other builds on the web to look up.



Area out here is rather flat although I'd like to participate in the BP MS 150 with a recumbent trike sometime in the near future. The BP MS 150, btw, is a 2-day charity ride--benefiting Multiple Sclerosis research--going from Houston to Austin TX, about 150 miles, which is why it's called the "150."

Good to have something to aim for , don't beat yourself up if you don't make the next one thou.



Figured a recumbent trike would help with the speed and going up the hills.

unless you are an athlete you will not be going fast on your first home built trike , even commercial one's can be slow up hills they are heavier than bikes and have the drag of the extra wheel , slowest of all up hills and can be scary down them ! however pedalling a trike up hill is generally faster than pushing a bike if you have the low gears for it.


I'd eventually make a second one for my wife who had never been taught to ride a bike.

give her the first when you have built a better second one , then maybe a tandem trike to share the pleasure ?

jdblessing
04-04-2016, 11:20 PM
Do you intend to get a welder and learn ? or farm out your welding to someone else , no one on here will dis you for farming it out and it may be the quickest way for you to get your first trike rolling.

I bought a cheap arc welder a while back. It's brand new, and still in the box. Looking to start learning welding technique this week while I'm on vacation. Figure once I have a bit of confidence in welding, I'll feel better about cutting the frames up, since I know I'll have a chance of putting them back together in some sort of workable form.




This forum is NOT only about Brads stuff others have altered his plans or build non Zombie machines , so is this simple enough ?

http://www.spiritofbalaton.hu/articles.php?article_id=75

it is a Delta called a Python however as it is front wheel drive there is no complicated rear wheel drive and not built up hubs/wheels the rear uses front bike forks and any size wheels you fancy.
Could easily be built with the frame from a large trampoline instead of square tubing , however round is harder to work with for a beginner

Interesting. Looks a bit like a SpinCycle minus the spin and with 20" rear wheels. And with a different steering system.


Good to have something to aim for , don't beat yourself up if you don't make the next one thou.

I won't. I at least want to come better prepared. And next time I'll have a loving wife to cheer me on, whether I make it all the way or not.


unless you are an athlete you will not be going fast on your first home built trike , even commercial one's can be slow up hills they are heavier than bikes and have the drag of the extra wheel , slowest of all up hills and can be scary down them ! however pedalling a trike up hill is generally faster than pushing a bike if you have the low gears for it.

I was looking at a 26" drive wheel, and the recumbent part would help me go faster with something to push against. I know not to expect speed uphill, but the trike would at least keep me balanced. I'm thinking of 15 to 18 speed may get me where I want to go. Not much need for hill-climbing gears apart from the charity ride.


give her the first when you have built a better second one , then maybe a tandem trike to share the pleasure ? maybe so. Haven't purchased any of the tandem plans yet though. We shall see.
:)

stormbird
04-05-2016, 03:36 AM
Interesting. Looks a bit like a SpinCycle minus the spin and with 20" rear wheels. And with a different steering system.:)

Sir joey turned a spin cycle into a road going trike :-

http://forum.atomiczombie.com/gallery/files/5/5/4-lilhornet.jpg

I think his build thread has gone , however I have loads of pictures of it , fast and low.

gearing is an interesting topic on a recumbent you need to be able to spin and have lower gearing than a bike , my trike with 20" wheels has a 48,38,28 with a 28 - 13 cassette and can climb a wall IF it can get the traction !

Although a stick welder can be used it is the hardest form of welding to learn when the material is as thin as bike tubing some of the welders cannot set the current low enough , however there are some on here than can do it so plenty of help available.

Seems you have it all in hand and quite a bit of knowledge already so just go to it.

Twinkle
04-05-2016, 04:55 AM
Even I was not born with the ability to weld - I did a little gas welding when I was still a tearaway teenager helping a friend with their garage - how I hated it , tried oxy-propane for cutting - that was fun !
It was only 3 years ago a mate who is a retired engineer helped me with my first streetfox before I started to practice with a second-hand corbora ( snap-on ) mig and that has seen a lot of action since !.
At least it makes me think with a hobby like this you think and get fitter .

BTW racing wheel chairs dont do 50 mph down hill !!!!!!!

regards emma

MrIdaho
04-05-2016, 09:01 AM
just a thought on the welder. I assume its a stick welder, still in the box, if so perhaps sell it and buy a GOOD mig welder. STAY AWAY FROM HARBOR FREIGHT mig welders as it is an AC mig, not the greatest to use plus it is IMO a good piece of metal for the scrap pile. Been there.
Good mig welder is Miller or Hobart that can run on 110v. Plenty big enough to learn how to weld.

jdblessing
04-05-2016, 11:50 PM
just a thought on the welder. I assume its a stick welder, still in the box, if so perhaps sell it and buy a GOOD mig welder. STAY AWAY FROM HARBOR FREIGHT mig welders as it is an AC mig, not the greatest to use plus it is IMO a good piece of metal for the scrap pile. Been there.
Good mig welder is Miller or Hobart that can run on 110v. Plenty big enough to learn how to weld.

I assume you're talking about a gasless MIG Flux wire welder. The gas MIG welders are much pricier. What about this (http://www.ebay.com/itm/MIG-100-Flux-Wire-WELDING-MACHINE-110V-90AMP-NO-GAS-WELDER-Auto-Feeding-Torch-/201465242654?_trksid=p2141725.m3641.l6368) one? I can't tell if it's AC or DC.

Twinkle
04-06-2016, 03:34 AM
I have tried a no gas mig and found that l could not get on with it .
My main machine now is a snap-on Cobora manufactured gas mig , even using a disposable bottle of argon mix l have enough to build a trike, at 15gbp a bottle it's still represents good value for a first class job , my other welder a Clarke l use a rent free argon mix that does represent value for money as it stands about a meter high.

The best part of the Cobora was , it was given to me and with a repaint ( it had turned orange instead of red ) and a new nozzle and trigger it is great

MrIdaho
04-06-2016, 08:37 AM
I would stay away from off brands. Remember this when you need a replacement part. This mig welder is identical unit I purchased off Amazon as a reconditioned unit. IF you win this bid then be sure to get a 10 lb spool adapter. Way cheaper than using the 2 lb spools. I found a supplier that I buy 10lb. spools (.035 flux coated) for $60, way less than HF buying the 2 lb spools at $20 per.
This auction has only one day left.

http://www.ebay.com/itm/Hobart-125EZ-500521A-Flux-Welder-/162028397519?hash=item25b9a523cf:g:bt4AAOSwzgRW1eD Y

jdblessing
04-08-2016, 02:24 AM
I appreciate all the information and suggestions. I'm going to give it a go with my stick welder for now, though, mainly because I already have it. That way, I don't have to wait again until I sell it, purchase another one either in store or online and have it delivered. A bird in the hand and all that. After doing further research here and online, I bought a few different sizes of 6013 welding rods for practice and will be going to a hardware store tomorrow to get some practice flat iron as well as some practice conduit and muratic acid to keep from killing myself from heavy metal poisoning.

stormbird
04-08-2016, 03:17 AM
I think it is a good idea to try it , you may be a natural !

however I would start with at least 1/8th [ 3mm ] thick and thicker if you have it to lay down some practice beads else you will just find it frustrating either rods sticking or blowing holes.

also shortening the rods may help you can always use the ends you cut off.

what sort of helmet do you have ? fixed or auto darkening ?

lots Youtube videos to help once you have seen brads stuff on here.

Gray Glider
04-08-2016, 04:20 AM
just a thought on the welder. I assume its a stick welder, still in the box, if so perhaps sell it and buy a GOOD mig welder. STAY AWAY FROM HARBOR FREIGHT mig welders as it is an AC mig, not the greatest to use plus it is IMO a good piece of metal for the scrap pile. Been there.
Good mig welder is Miller or Hobart that can run on 110v. Plenty big enough to learn how to weld.
With a few parts and some work those HF flux welders can be made to perform pretty good. Convert them to DCEN and free up some airflow . For about $60 dollars you will have a much better welder than the factory delivered,but it still isn't a Hobart or a Miller..

jdblessing
04-09-2016, 03:10 AM
I think it is a good idea to try it , you may be a natural !

however I would start with at least 1/8th [ 3mm ] thick and thicker if you have it to lay down some practice beads else you will just find it frustrating either rods sticking or blowing holes.

also shortening the rods may help you can always use the ends you cut off.

what sort of helmet do you have ? fixed or auto darkening ?

lots Youtube videos to help once you have seen brads stuff on here.

I got 1/8th thick and thinner. Figured I'd be using the thinner ones on the actual projects so should get used to using them. As for the helmet, I got a fixed one as it's cheaper by far. By the time I got my practice iron today it was too late to do any actual welding. But at least I'm getting closer.

darnthedog
04-09-2016, 11:24 AM
With a few parts and some work those HF flux welders can be made to perform pretty good. Convert them to DCEN and free up some airflow . For about $60 dollars you will have a much better welder than the factory delivered,but it still isn't a Hobart or a Miller..

The advice to stay away from HF welderrs has been made numerous times. 1) even with mods they do not hold up with our usage and learning curb. We as newbie welders tend to burn them up. 2) Unless you are comfortable with learning electronics on top of welding, it can be dangerous due to storedog voltages.

Ed Pedal-car did a nice break down of welder research. He was introduced to gas shielded verse Flux core welding. Very dramatic improvement over the AC welder he was using.

He was not the first, I doubthe will be the last to note the difference from a HF verse a decent machine. Plus with some many offers over the months of used welders- there is really no need to waste $ on a HF machine.

MrIdaho
04-09-2016, 04:58 PM
My sedements exactly Darnthedog.
Using a stix welder for the thin material we are using is a lesson in stretching ones patience.

Gray Glider
04-10-2016, 02:19 AM
I have 50 plus years in electronics, I can accomplish the modification of one of these welders,that cost all of $89.00 with discounts.After the modification i will have about 135.00 in it and the reviews of people that have done it are positive.Many years ago i sat down and calculated the cost of manufacturing a television set and am still amazed at the willingness of ordinary people to pay for what they do, like i-phones,etc. After I have mastered the finer points of MIG welding I might try to find me a better welder,but until then I will modify and use the Harbor Freight model,and be happy with the experience.

Gray Glider
04-10-2016, 02:27 AM
I forgot to mention that Harbor Freight will gladly give me another one if I burn up the first one or the second one. If I purchase a used Hobart MIG welder and it fries the first time I strike an arc I have no recourse. So until I am proficient at MIG welding I will use the modified HF welder.

MrIdaho
04-10-2016, 02:43 PM
I have two full wave bridge rectifiers and I think I still have a large capacitor.
You pay shipping and they are yours.

Gray Glider
04-11-2016, 01:08 AM
What is the current rating on the rectifiers and the voltage rating on the capacitor? The rectifier must be capable of at least 150A.I would gladly pay shipping on them if I can use them.