Newbie Seeks Guidance From Experienced E-Bike Motor Engineer

[Film_Director_Mark]

Hello Experienced E-Bike Motor Engineers:
All hail to experienced E-bike motor engineers more learned than I. I consider myself very much a newbie, although I have been following the E-Bike movement for a couple of years now and have earnestly been doing my best to educate myself in as many aspects pertaining to efficient E-bike speed and torque as is practical. I have dreamt of designing and building my very own Recumbent E-Trike using ultra light materials mainly of aircraft grade T-6 Aluminium, carbon fibre, and magnesium. I have been researching various electric and non-electric trikes. I would like some advice on what kind of a motor I should use to efficiently push this bike at two very different speed settings. First, allow me to explain my specifications........

1. I live in Canada, and there is a legal limit imposed on how strong a motor I can use. In Canada they limit us to an E-Bike motor of 500 Watts Maximum. My understanding is this is not a very powerful motor.

2. To be legal in Canada, the maximum speed an E-bike (E-Trike ?) can go is 20 MPH/32 Kmhr. This is not particularly fast enough for me.

3. I was thinking of using Cycle Analyst V.3 with a locked setting which would render my Canadian made E-Trike totally street legal, but also adding a secondary, "backdoor," or "Off Road" setting, which would allow a much higher maximum top speed.

* I am seeking advice on what type of 500 Watt motor would be best to meet these design specifications ? Also, what is the maximum speed obtainable on a 500 Watt motor ?

4. I want my custom E-Trike to have the maximum possible range between recharges.

5. I want to have good torque to climb steep hills. There are many steep hills and mountains here on Vancouver Island.

6. I want my E-Trike to have the shortest possible wheel base for an E-Trike.

7. I want to design my E-Trike in such a way as to be able to have the maximum size paniers to be able to carry the maximum possible load.

8. I am 6 feet tall and weigh in @ 300 LBS !

** What size should my wheels be ?

*** Should my wheels all be of equal size ?

9. I want both front and rear lights to run off of the main battery.

10. I want there to be a rear stop light.

11. I also want to include bright front and rear turn signals.

12. I want an internal gear cassette.

13. I need an adjustable seat.

14. At least 5 inches of ground clearance.

15. Front and rear suspension.

I hope giving these extra specifications info helps to determine what 500 Watt motor spec ?

Mark

 

[e-beach]

Hey Mark! I know you have said you are from Canada, but for future posts and ease of remembering, do this first.


OK, so now that that is done, it sounds like you need to contact Grin if you haven't all ready done so. They are super nice and will help you out.
Grin Technologies
20 East 4th Ave
Vancouver, BC
V5T 1E8
(604)-569-0902

Also, if you haven't seen their motor simulator, go here http://www.ebikes.ca/tools/simulator.html

Some answers to your questions

To be legal in Canada, the maximum speed an E-bike (E-Trike ?) can go is 20 MPH/32 Kmhr. This is not particularly fast enough for me.

Depending on what you want to build a 48v or 56v motor at 30 to 40 amps will get you going faster the 20 MPH/32 Kmhr. the question then becomes ....is it legal?

I want my custom E-Trike to have the maximum possible range between recharges.

Range on an e-bike depends on watts used on your ride. All kinds of things come into play on that subject, but the easist way to gain distance is to have a battery pack with a large Amp-Hour battery. The weight of a large battery will come into play.

I want to have good torque to climb steep hills. There are many steep hills and mountains here on Vancouver Island.

Hills can be concurred with a High torque slow wind motor, or a Geared hub motor, or a High voltage motor with a High amp controller or a Mid-drive motor so you can use your gears.

** What size should my wheels be ?

26" or 700cc will work.

*** Should my wheels all be of equal size ?

They could be different sizes like a 26" hub motor in the back and a 16 inch wheel in the front if that is what you want.

I want both front and rear lights to run off of the main battery.

You will need a dc-dc converter setup

I want an internal gear cassette.

You may have to go front wheel drive or mid-drive motor for that.

Also, check out Amberwolfs “Crazy Bike”

Edit: Also check this out....https://www.electricbike.com/modified-hub-motor/

 

[Film_Director_Mark]

Hi E-beach:
Hey ! Thanks for the info I'm finding the motor simulator on Grin's page does not list the various different motors according to their *Nominal Wattage. I need to know this if I'm going to be able to choose a motor with the correct maximum legal *Nominal wattage allowed, yet know it will stand up to my "secret setting," whereby I will need to push enough extra voltage and amperage to achieve high speed, but not fry the motor. Also, I think I will need to speak with Grin about what 500 Watt DC motor can handle extra voltage and amperage very well. Maybe I need a special Grin wound motor ? I have also heard the Bafang 500 Watt hub motors perform very well for cargo bikes (Like Juiced Riders' ODK v.3 front wheel hub drive @ 500 Watts Nominal), they are available with several different windings for different performance characteristics. i.e. More torque for hill climbing and heavier loads, or higher top speeds, but lower torque. To what degree do the size of the copper windings in a 500 Watt motor affect these characteristics ? Looks like I'm going to have to Science the crap outta this

Mark

 

[Film_Director_Mark]

Hi Again e-beach:
I spoke with Ben Goldberg at Grin in Vancouver and he gave me some advice about some motors and controllers. Ben advised me that what I am attempting to do is very "high end," and is mostly outside of Grin's general expertise. Grin is focusing more on those who are more looking to increase their E-bike's load capacity to carry their children and climb hills better, and go maybe 40 Kmhr, but I'm looking to achieve a top speed of double this to obtain 50 to 60 MPH (80 to 101 Kmhr). Ben also agreed with me he considers our current Canadian *Nominal 500 Watt limitation doesn't really make sense, and is not commensurate with how these motors operate. I put it to him that maybe a more practical way to go would be to have a lower powered motor going through some kind of drive train toothed belt interface to mechanically step up the speed by employing some common gear ratio and wheel size physics ? Ben agreed this could work and suggested I give the guys at Outrider USA a call to discuss this, since I think they have some expertise in this area.

 

[Film_Director_Mark]

Hi e-beach:
I spoke with Zach Thomas at OutRider USA, who is also a well known E-Trike engineer. Zach was so helpful ! Zach says they literally took a year off and have been devoting themselves to re-engineering their wonderful E-Trikes "Alpha," and now the "Horizon." They have been facing many of the exact same obstacles as I in the creation of their own E-trikes and were able to provide me with some suggestions and excellent pro advice about how to go about engineering the electric drive in my E-trike build. Zach confirmed my strong suspicions that success is not be found in motor spec alone, but also in mechanical gear reduction solutions and the right high voltage controller. Zach suggests a 5:1 drive ratio @ a 2 stage reduction. Zach says he is doing 70 + hour weeks doing nothing but R & D. They are building their very own custom E-Trike frames for their new Alphas and Horizons with custom air suspension ! Sweet ! These folks at OutRider USA really know what the heck they are talking about in the world of E-Trike building, so I'm listening very closely to every word of wisdom Zach suggests a serious look at Astro-Flight's 3220 5 Wind motor, which produces a stunning 8,000 to 11,000 Watts of power @ 48 Volts. Zach says to take a look at Castle Creations HV160 Amps Controller with fan or without. It's not particularly expensive and can be run continuously @ 320 Amps all day without frying out My purpose here is not to produce some Canadian made knock off of the highly excellent Outrider USA E-Trike, rather to march to the beat of my own drum, and possibly integrate some variation of a known, workable, solution to effectively drive my E-Trike. Looks like I will be using Cycle Analyst software v.3 for my dash board speedometer, and controller settings and readouts. Is Cycle Analyst in the public domain, or is it owned and licensable ?

 

[Chalo]

I have dreamt of designing and building my very own Recumbent E-Trike using ultra light materials mainly of aircraft grade T-6 Aluminium, carbon fibre, and magnesium.
[...]
I am 6 feet tall and weigh in @ 300 LBS !

These two things above are not consistent with each other, and exotic materials don't lend themselves well to one-off projects either. Consider that you may want to make additions and revisions, so using a weldable material that doesn't need post-weld heat treatment would be a good idea. If you want something fancy, make it seamless 4130 chromoly aircraft tubing with 0.9mm wall thickness. You can easily find that in diameters up to 1.75", in 1/8" increments.

What size should my wheels be ?

20" is best for structural integrity and aerodynamic qualities in a 'bent trike. 700c is best for ride quality, rolling resistance, and selection of fast tires. 26" is a compromise between the two that offers a huge variety of rims and tires to choose from. I'd probably use 20" front, 26" rear in a tadpole configuration.

If you're thinking tadpole layout, with rear motor, then 20" rear makes sense from the standpoint of motor performance and wheel integrity. Hub motors make weak wheels, but you need strong wheels.

I want an internal gear cassette.

Cassette gears are external; internal gears aren't cassettes (and preclude the use of a hub motor on the same wheel). Which are you talking about?

Front and rear suspension.

Think about doubling the weight of your trike, and quadrupling the cost and build time for the frame. That's pretty much the deal.

If you want cassette gearing, rather than internal gears, there are a few hub motors that work with them. I think they're all geared hub motors, but it's hard to know about all that's available.

For several reasons, crank drive seems like a better choice for your needs, but it's inherently difficult to limit it to any particular top speed. If you did use a crank drive e.g. Bafang BBS02, you'd have a full choice of strong wheels, variable motor reduction ratio for both hill climbing and high top speed, and the opportunity to use any kind of bike gearing you want.

 

[Film_Director_Mark]

Hi Chalo:

These two things above are not consistent with each other, and exotic materials don't lend themselves well to one-off projects either. Consider that you may want to make additions and revisions, so using a weldable material that doesn't need post-weld heat treatment would be a good idea. If you want something fancy, make it seamless 4130 chromoly aircraft tubing with 0.9mm wall thickness. You can easily find that in diameters up to 1.75", in 1/8" increments.

......I was thinking about the T-6 Aircraft grade aluminium because of its relatively easy machinability. I was thinking of using the carbon fibre in places other than part of the frame itself. i.e. Carbon fiber for rear Paniers mounts. Magnesium for the reduction intermediate drive gear box and possibly for bolts and screws.

20" is best for structural integrity and aerodynamic qualities in a 'bent trike. 700c is best for ride quality, rolling resistance, and selection of fast tires. 26" is a compromise between the two that offers a huge variety of rims and tires to choose from. I'd probably use 20" front, 26" rear in a tadpole configuration.

......I was thinking of a 20 inch dual front wheels with a larger rear 26 inch wheel, since this would be a reasonable compromise between performance and the ability to use extra wide rims for Fat Tires :lol: I like fate wheels :lol: I want a very cushy ride.

f you're thinking tadpole layout, with rear motor, then 20" rear makes sense from the standpoint of motor performance and wheel integrity. Hub motors make weak wheels, but you need strong wheels.

.....I'm leaning more toward using a small, but powerful 5 wind type performance motor to a possible 2:1 gear reduction box mounted somehow and somewhere behind the seat after talking to Zach Thomas of Outrider USA. Zach makes some compelling arguments for the design and implementation of such a drive system. I think much careful thought must be put into threshing out the specs for the wheels and wheel axels and bearings. I don't think I want to make 50 + MPH on regular type bicycle wheels and bearings. A wheel failure at such speeds could prove to be fatal What happens when I hit bumps on the road at these speeds I think I have to really be careful here and take extra time in looking at the absolute need of some form of suspension and steering, which is not oversteering me at high speeds. I don't know this for sure, but I strongly suspect, and it stands to reason from a pure physics POV that the faster you go, the less steering you require, therefore, some type of a dampening, or hyper control system must be engineered into the steering of my custom E-Trike. Also I find most trikes to be rather long in their wheel base from front to back. I don't like this. I was thinking about making my E-Trike as short from the front to the back as I possibly can be, yet using width to create some extra stability. I want to be able to pick this baby up and put it in the pickup

Cassette gears are external; internal gears aren't cassettes (and preclude the use of a hub motor on the same wheel). Which are you talking about?

....Internal hub shifting type of gears. No external cassette gears for me.

Think about doubling the weight of your trike, and quadrupling the cost and build time for the frame.

....I don't think my E-Trike will be too light. I think my problem will be keeping it to a reasonable weight - Especially after the addition of a huge, honking battery pack I'm going to need to stick in the base to allow for the kind of range I'm looking for (200-300 Miles) Some custom made variation on Lithium-Ion technology, no doubt.

For several reasons, crank drive seems like a better choice for your needs, but it's inherently difficult to limit it to any particular top speed. If you did use a crank drive e.g. Bafang BBS02, you'd have a full choice of strong wheels, variable motor reduction ratio for both hill climbing and high top speed, and the opportunity to use any kind of bike gearing you want.

.....Hmmm ? This is also interesting. I'm wondering if this would not be a less expensive route to go ?

Once I arrive at a final spec for my E-Trike build, then I can price out the parts and see if I'm looking at a budget I can afford ? Thanks for your input Chalo. This helps me thresh out the E-Trike's spec.

 

[e-beach]

........ I think much careful thought must be put into threshing out the specs for the wheels and wheel axels and bearings. I don't think I want to make 50 + MPH on regular type bicycle wheels and bearings. A wheel failure at such speeds could prove to be fatal What happens when I hit bumps on the road at these speeds .......

Guys around here who want to go fast sometimes use moped tires and rims etc.

 

[Film_Director_Mark]

Hi e-beach:
I think I'm going to have three wheels custom made, which will be built to a spec, which can handle both the weight and the speed. If I'm going to go and sit in a chair which essentially catapults itself down the road, pushed by a very effectively powered and balanced motor and mechanical reduction system, then I better pay special attention to wheel centrifugal velocities, tire behaviour at speeds over 30 MPH, and steering linkages and design. I'm a newbie by all measures to this enterprise, so I need to get this right the first time, or some really bad things could happen

Mark

 

[e-beach]

Bad things can happen at slow speeds. My worst crashes have all been under 10 mph. Also make sure you incorporate something that will let you be seen by ICE drivers ska "cagers".

Even if they see you they may try to turn in front of you or on top of you. It is a common occurrence to e-bike riders and has happened to me more times that I can count......like pretty much every day. So also incorporate a defensive riding strategy from the beginning. Make sure you are not so low that it is hard to see you.

 

[Film_Director_Mark]

Hi e-beach:

Bad things can happen at slow speeds.

....I'm the kind of guy who manages to fall off upright regular bikes fairly often I've driven mopeds, scooters, and motor cycles since I was 14, and I've had every kind of major wipe out - including sliding under an 18 wheeler and out the other side ! Recumbent bikes have allot going for them. You generally seem to have a better overall field of view, and there's not so much pressure on your lower body and your lower back muscles while driving. Since I had abdominal surgery about two years back, I'm only now starting to get back some of my strength. If I get the seat angle right, I can peddle one of these without the strain to my stomach muscles. You would be surprised what you use your stomach muscles for ? Everything from laughing, sneezing, standing, walking, crapping, and sitting upright on a bike and especially leaning forward and peddling hard up a hill. The recumbent position seems to take a great deal of overall strain off of your body. I have lost a great deal of leg and knee strength, which I must have back With a Recumbent E-Trike I can peddle assist my way up hills and across country at an intensity my busted gut can stand, while exercising the heck out of my weak legs. I can put clips on my shoes, so if I get too tired to hold my legs up anymore, then I can just let them hang there on the peddles and E-Throttle my way up the next hill.

Even if they see you they may try to turn in front of you or on top of you. It is a common occurrence to e-bike riders and has happened to me more times that I can count......like pretty much every day. So also incorporate a defensive riding strategy from the beginning. Make sure you are not so low that it is hard to see you.

....I will be using not only a bright LED rear light, but it will also incorporate a stop light feature. I will have turn signal indicator lights front and back, and a very bright headlight. I will also imploy a big LED Flag pole and reflective Canadian flag. I'm also giving some consideration to wet rain conditions, being I live on Vancouver Island, where resides Canada's only Boreal Rain Forest :wink:

 

[Chalo]

I was thinking about the T-6 Aircraft grade aluminium because of its relatively easy machinability. [...] Magnesium for the reduction intermediate drive gear box and possibly for bolts and screws.

Understand before you start that you cut the strength of heat treated T6 aluminum to T0 at the weld; that's about a quarter of its original heat treated strength, at the point of highest stress. To recover the material's strength, you have to heat treat the entire structure in a special furnace. That might be worth your expense and effort, but keep in mind it has to happen again each time you make a change or weld on another doodad. Meanwhile, the weld zones on chromoly frames are at least as strong as the base material.

Magnesium is soft yet brittle, prone to an undesirable mechanical quality called "creep", wildly corrodible, and the least stiff structural metal you could name. The only good news about your suggestion of using magnesium bolts is that there are none for you to buy.

Even people who build flying machines from scratch use chromoly steel tubing. Even exotic racing gearboxes are built on aluminum cases. Take the hint.

Think about doubling the weight of your trike, and quadrupling the cost and build time for the frame.

....I don't think my E-Trike will be too light. I think my problem will be keeping it to a reasonable weight - [...]

What I meant is that if you want full suspension, your trike will weigh double and cost quadruple of what it would if you didn't use suspension. Go for fat tires and a suspended/resilient seat.

 

[Film_Director_Mark]

Hi Chalo:

Meanwhile, the weld zones on chromoly frames are at least as strong as the base material.

....What is the cost ratio of Chromoly Steel Tubing versus T6 Aluminium ? Also, what is the weight difference of Chromoly Steel Tubing versus T6 Aluminium ?

Even exotic racing gearboxes are built on aluminum cases. Take the hint.

....Meaning what ? I was planing on using higher T rated Aluminium for the gears instead of steel, because I want to keep the weight down. I'm almost positive I will employ toothed rubber automotive type belts for the reduction gear box out drives I'm thinking of building. I may opt for 16 inch wheels as well. I would like to make my E-Trike at least 1/3rd shorter in length as compared to an Outrider USA Alpha E-Trike. It looks like it's down to (2) two possible motor drive contenders for my design. A) Astro Flight's 3220 - 5 Wind 48 Volt motor, or B) The Crystalite-Crown MTC40100R hub motor. The second choice is more affordable, but I would not lace it to a rear drive wheel. I would use some sort of a mid-drive mounted position setup and bolt it to the frame and connect it into the 2:1 reduction gear box via an attached gear for toothed drive belt to the central motor shaft. According to Grin's Motor Simulator, this motor tested out as having the best overall voltage and high current characteristics of any motor Grin sells, including their own hub motors.

What I meant is that if you want full suspension, your trike will weigh double and cost quadruple of what it would if you didn't use suspension. Go for fat tires and a suspended/resilient seat.

....Yup. I was planning on fat tires, but if I go super small with an all 16 inch wheel solution, I may wind up having three custom wheels made just to get the super wide enough rims to support fat tires. Can I even get fat tires, or wide enough tires for rims this small ? For the seat I will definitely make it air suspended. I will also make sure a proper rear head rest is included to reduce neck strain. The seat will also be adjustable in both its tilt and it's position forward or back.

 

[Chalo]

Where have you ever heard of aluminum gears? There is no such thing. Because aluminum is not a suitable material for gears-- it doesn't have enough surface hardness for that job. It has very limited resistance to fatigue cracking.

You're displaying a fundamental obliviousness to materials properties. That's understandable, but if you don't have it, you need to defer to the technical state of the art. Magnesium bolts? Aluminum gears? It's laughable. Unless you have some very special insights based on deep understanding of your application, bolts and gears are both steel, period. That's what works.

And if you don't have access to your own heat treating oven, HSLA steel like 4130 chromoly is also what works for your frame.

 

[Film_Director_Mark]

Hi Chalo:
Ok friend. I hear your concerns. I don't think I ever stated I was be any means a metalurgical expert. It's clear to me you have a much deeper understanding of how various metals behave under various applications.

Where have you ever heard of aluminum gears?

.....Here's what I was thinking. I was considering the possibility of using high grade hardened commercial aluminium for the gear reduction box, because what I envision for my 2:1 reduction is not cogs to chain drive per se, rather, I propose to employ a certain high hardened aluminium toothed spindle turning on the shaft coming out of the motor. The motor shaft with it's hardened aluminium toothed spindle would have a rubber toothed belt coming off of it, and this belt would go to an intermediary high hardened aluminium toothed wheel of a pre-determined tooth number (I don't know what tooth number this shall be yet ????) Next, there will be a secondary toothed belt coming off of the reduction wheel and going out to a large, torquey high hardened aluminium drive spindle mounted on the rear drive wheel. The main consideration of doing this in Aluminium is both to reduce the weight of my E-Trike, and also reduce cost of production, because Aluminium can be machined by myself instead of going to expensive shops. Now, if this means I have to bake my parts to re-harden them, or take my parts to be specially welded by a high welding expert, then, perhaps, it might be worth the trouble if I can significantly reduce the overall weight of my E-Trike without sacrificing strength, durability and safety on the road. Perhaps my proposal to use aluminium is insufficient to my application I have seen high grades of super light and hardened aluminium used in many load bearing applications quite successfully. I would not think the commercial Aircraft Industry would be using so much of it, as well as magnesium and carbon fiber, if these materials were not so dependable ? Maybe I'm wrong about this idea when it comes to building my E-Trike ????

Mark

 

[Chalo]

Okay, let's back up.

Gears engage other gears. Sprockets engage chains, or in some cases, belts. Gears would self-destruct if made from aluminum, while aluminum sprockets are fine.

All else equal, chain sprockets are more efficient and less demanding of precision than gears by far. Belt sprockets are in between regarding their precision requirements, and probably inferior to either one in their efficiency.

 

[Film_Director_Mark]

Hi Chalo:

All else equal, chain sprockets are more efficient and less demanding of precision than gears by far. Belt sprockets are in between regarding their precision requirements, and probably inferior to either one in their efficiency.

....I was wondering if you have seen the drive system used on Outrider USA's Alpha and Horizon E-Trikes ? I was wondering what your opinion of their toothed belt drive 2:1 reduction gear box was ?

 

[Chalo]

I don't know specifics of their belt reduction system, but well made toothed belt drives are a proven way to get relatively quiet, reliable, low maintenance power transmission.

One of the first e-bike drives I designed used a shafted motor, a 4:1 belt first stage reduction, and a 3:1 chain second stage. I had no trouble machining the sprockets with adequate precision, but the motor shaft had enough runout to be a problem for the belt. Every part of a belt drive has to be concentric and parallel for consistent belt tension and good service life. Precision is much more critical than in a chain drive.

 

[Film_Director_Mark]

Hi Chalo:
Super Hardened Aluminium is just within my reach to self machine and save a ton of cash not having to engage a shop to do what I can't. I still can't weld and looks like I'll require special welding services. The baking to super harden in an oven will be the final step after I test assemble the frame and other parts together I would think ? Correct ? There are allot of different variations of commercial Aluminium metals to choose from. Time for me to delve into what's available with what strengths and characteristics. I'm fairly confident there is an Aluminium type out there which has the proper characteristics for load bearing and dimensional stability I'm looking for

 

[Miles]

There's no such thing as "super hardening" of Alu. alloys......... If you need a good wear surface (pulleys etc.), you need to get it hard anodised.

 

[Film_Director_Mark]

Hi Miles:

There's no such thing as "super hardening" of Alu. alloys......... If you need a good wear surface (pulleys etc.), you need to get it hard anodised.

.....The commercial Aerospace Industry is using it I'm no expert by far about metallurgy, or how these various flavours of metals all behave, but I'm seeing some developments in Aluminium and Aluminium alloys which gives me hope I will be able to machine some of this stuff myself. Welding, uhh, forget it, but I have a buddy who has an impressive welding setup and seems to know how to use it, so maybe he can help me and teach me what to do ? I predict this thing will take me 1 year or more to complete. There's just soooooo many aspects of this project to consider I will definitely post links to pictures I will take on here as my E-Trike Project progresses.

 

[Miles]

The commercial Aerospace Industry is using it

A good thing that you're using "aircraft grade" Alu. then

 

[Film_Director_Mark]

Hi Miles:

A good thing that you're using "aircraft grade" Alu. then

....Yeah, I think this is what this project may very well require ? Really light, hard, and specially tensile strength tough Aerospace grade Aluminium. It will be interesting to machine. I might as well buy 20 or 30 milling bits now :lol:

 

[Chalo]

Super Hardened Aluminium is just within my reach to self machine and save a ton of cash not having to engage a shop to do what I can't. I still can't weld and looks like I'll require special welding services. The baking to super harden in an oven will be the final step after I test assemble the frame and other parts together I would think ? Correct ? There are allot of different variations of commercial Aluminium metals to choose from.

If you are comfortable with the idea of post-weld heat treating, then you are going to use 6061-T6 or T6511 tubing and plate. It's pretty easy to machine, bend, and weld, which makes it the most common structural aluminum alloy.

7005 alloy is often used for bicycles because it does a passable job of solution heat treating at air cooling rates after welding. So you can skip the first high temeperature stage and water quenching, and only do the lower temperature artificial aging step. Strength is approximately the same as 6061. Availability is much less than 6061.

There are plenty of other alloys with higher strength than these two, but most aren't weldable by customary means. They're also much harder to find in appropriate tubing sizes than the alloys I mentioned above. Don't be tempted by these alloys; they will cause you more trouble than they are worth.

All aluminum alloys are almost identical in stiffness, regardless of their strength. They are all one third as stiff as steel.

The T codes in aluminum alloy names are designations of process, not quality. T3 is solution heat treatment plus natural aging, for instance, while T6 is solution heat treatment plus artificial aging. T6511 is T6 plus further cold working. Different alloys attain their optimum properties with different processes.

Bicycle manufacturers use aluminum for frames largely because it's cheaper than chromoly to build with in a mass production setting. Almost all home builders and artisan framebuilders use some kind of steel. I don't think you'll be sorry you used steel for your first article.

Do not be deluded into thinking you'll get exactly the results you want on the first try, no matter how much effort and money you devote to it. All designs need iterating, and aluminum isn't so good for that.

 

[Film_Director_Mark]

Hi Chalo:
I have to put some calls out, but there are three other kinds of machinable aluminium alloy used almost exclusively in the aerospace industries, which is brand new. I'm going to find out what those are and see if they should even be considered ? Thanks for your expertise in metals Chalo You've obviously built some stuff before

Mark