Usual Question for the Wheel Experts
 

Title Spell Check: Unusual* Question for the Wheel Experts
Hello, I am asking for some advice regarding bicycle wheels and my current project.
I am currently making a DIY Segway, and wanted to replace the wheels with large diameter, then wheels. Thus, I am wanting 20" bicycle wheels.
http://s20.postimg.org/ml2s4y60d/Finished.jpg

It is not going to be particularly easy to achieve this, as the two wheels are needing to be attached directly to the motors. The hubs for such motors are below:
http://s20.postimg.org/pkivjju99/photo.jpg

I have to different types of bike wheels that I have in mind for this project.
1.One is using a 20" Skyway tuffwheel, and somehow putting a 'keyed' hub in replacement of the stock hub and bearings. Then machining a hub that bolts to the motor and has a keyed shaft that will go through this hub.
2.The other is to custom machine a hub very similar to normal bike hubs that can be bolted directly to the motor, then take this hub to a local bike shop and have them lace and true it on a rim.

I have seen both of these options be done for the exact same motors I am using. However, I have a question or two for each of these ideas, and will voice other issues I believe I may come across. I appreciate any feedback/suggestions.

Skyway's
Assuming since this is a bike forum, everyone knows about the skyway wheel and what they look like. Furthermore, it is probably common knowledge you can buy them at several bmx part stores.
What my main and only problem is when it comes to these is that if I were to buy them from an online bike store, they come with the bearings,axles,etc.
http://www.planetbmx.com/shop/images...heel_047-1.jpg
Obviously, I can't do what I intend with this kind of hub/bearing/axle on the wheel.
What I really need is the hub that can be found on the skyway website like below:
http://www.skywaywheels.com/graphics...keyway_sml.jpg
I called the skyway factory, but they said they only make a few of the wheels with this hub.
So my question is, is it possible to knock out the axle/bearings/etc, and somehow press fit or epoxy a 'keyed' hub into the wheel? Or is this not possible due to those being molded into the wheel itself?
The exact thing I'm going for can be seen in the first couple of pictures at this link, which isa Purdue engineering senior design project team's segway. https://engineering.purdue.edu/ece47.../pictures.html

Custom Hub-Spoke/Lacing
The downside to this one is the fact that lacing and truing a tire is very far above my head. I wouldn't have a problem designing, and machining the two hubs, but I would have to take them to the bike shop and have a guy do it. I went in and asked him how much it would be and he said it would be a $45 charge per wheel, plus the cost of spokes,rim, and tire/tube. Is this reasonable? I really was not wanting to pay $200+ on these two wheels.

That's a better approach.

Bicycle wheels have thin axles which work because they're supported on both sides which you won't be doing.

Building bicycle wheels is so simple that children can do it. Jobst Brandt beta-tested his book _The Bicycle Wheel_ by having each of his grade school sons build a pair of wheels using only the book for instructions and no additional help.

I do a little recreational machining with both Bridgeport and CNC vertical mills and build my own bicycle wheels.

Where you have enough mechanical aptitude to be useful in a machine shop you should have no problem with the wheels.

Yes. In places with higher costs of living a wheel build can run $70-$90.

Fifty years ago most boys took a shop class in high school. And the schools had automotive and machine tool clubs where we got useful experience with the tools.

Now there's a dozen kinds of electronics competing for time. Schools are afraid somebody will get hurt. It's a different world.

I think you could make a replacement core the OD of the bearings, and press that in.
Add Loc tite., the core should be able to use that motor and its 4 Bolts.

unless it wont handle end loading .. then You may need the wheel on a separate axle and chain drive
onto it.

then have the keyway for drive torque transfer..

Hi,

Wheels aren't rocket science and your severely over complicating
the issue, as are are those called "engineering" students, who
seem to have never heard of "KISS" and real engineering.

The lack of understanding of the real issues in their wheel fixtures is awful,
clueless, and ineptly pointlessly complicated. It isn't complicated at all if
you understand wheel design for different applications.

It wouldn't be hard to mount those wheels directly on the motor flange.

rgds, sreten.

Could you use fixed gear hubs without the axles? Drill a sprocket for the hub bolts, then thread the wheel on to it? You'd have to hit a pretty big pot hole going pretty fast to crack the hub shell.

I am an engineering student, which could very well be why I apparently am way over complicating this. However, maybe if I were a mechanical engineer instead of an electrical I may not be having such of a hard time with it. Admittedly, if I knew anything at all about "wheel fixtures" then I probably wouldn't be asking for advice either. But, unfortunately, I do not know crap about bikes, wheel fixtures, or the "real issues" of them.
However, I am always willing to learn, and even better if its from real engineers who have heard of KISS.

While you say it is not complicated at all to mount these directly to the motor flanges, would you care to share how you personally would do so?

Thanks for the suggestions,
The segway(its the blue one in the picture above) is made out of steel, then the heavy duty motors, then on top of that the batteries all together add up to around 70 pounds without the rider. I figure that weight combined with end loading, it would end up breaking.
As for your other suggestion, the Segway frame and motor mounts are designed for the wheels to be directly attached. There isnt any room for the chain/sprocket/etc.

This is idea I have yet to consider. I will research more about it.

The bolt pattern on the motor is 1 inch diameter, with 5/16 bolts. http://www.robotmarketplace.com/prod.../npc-64038.pdf

I'm an engineering student, and I've heard of KISS! OK, I prefer Motley Crue if I'm honest with you, but they weren't bad :thumb:

OP, I'm liking the idea of making a custom hub that bolts onto the motor. As others have said, lacing wheels (not "tyres") really isn't complicated, the usual way I prove that is by saying that I learnt to do it aged 14 or 15, using nothing more than Sheldon Brown's wheelbuilding article. Not sounding my own horn there, I freely admit to being a clumsy ass. I'm showing how damn easy it actually is.

While I would prefer to have the skyway wheels on it, I will probably end up going this route.
I think the guy I talked to at the bike shop greatly exaggerated on how hard it was to lace a wheel from the way you guys talk.
I started throwing together a hub design on Creo Parametrics today at my internship. Tomorrow I will do a little more work with it, and post it on here. What I am worried about the most with it is making it to where its not 'in between' spoke sizes. Because the way the guy talked there is a considerable amount of variables that factor in to the size of spoke. I'll do more research on it tonight though.

There are spoke length calculators on line you can use to design your hub.

I wouldn't worry about that, spoke lengths vary by 2mm between each size (at least the ones my co-op buys do), you're bound to be able to get the right ones for your hub as long as you don't come up with a completely mad design.

You might consider slide-on hubs like those used on wheelchairs and trailers. Replace the bearings with a pressed in keyed bushing. Depending on the torques involved, you might have to use an anaerobic adhesive, unless the press fit is tight.

Hi,

I was an Electrical Engineer but not too shabby on the Mechanical side.

Nothing is going to be stronger than the flange the wheel is connected
to, although the wheel can reinforce the flange if the shaft is thicker.

Pretty much 4 bolts through a decent thickness washer to match the wheel
with all the plastic wheels (of any type) central gubbins removed and slots
for the bolts added will work. Arrangements to maintain concentricity and
trueness will help a lot and need some thought, to keep it simple.


But I wouldn't go without a basic concentricity mechanism,
between the motor rotor and the wheel, very easy to machine
on a lathe for plastic wheels, or machine L shaped rings.

rgds, sreten.

Given this a fixed wheel on a electric motor, most
bike knowledge is irrelevant, and at best, confusing.

An appreciation of how hopelessly and pointlessly
overengineered, which is not engineering in any
sense I know, the linked wheels are does help.

The alumunium version almost certainly chewed
up the the motor joint - just dumb engineering.

Consequently the finer details may be appreciated.

How about disc brake hubs? Cut an adapter plate that mounts to both the motor axle and where the disc brake would sit. Ignore the hub axle. Lace the rims of your choice to the disc brake hubs. Shimano Deore are thick and sturdy and inexpensive.

I like the idea, I'd take it a step further and fab a piece that would tie it together with the axle, which need not spin, so it could be further reinforced. I enjoy these sort of projects.

Logan-

Looking at the pictures provided on your "engineering.purdue" link gave me some insight, and provoked a thought. You've machined some hubs that attach to the motor's output shaft. If these were machined to the proper diameter and depth, you could press fit a Sturmey Archer drum brake hub on them. Lace up the 20" rims of your choice and go ride.

Logan:
why are you not talking to the faculty advisers ?, you are paying for them.

This project has no connection with my university. Also, to clarify, the link I provided of the Purdue segway has just been used for reference on some of the various components.

I go to Valparaiso University, and am close to one of the Electrical Engineering professors, who gave me all of these parts and frame left over from a senior design project about 5 years ago when I expressed interest in making a segway or RC lawnmower as a personal summer project. It ended up being quite a find, as it is around $1500 in parts (motors, motor controllers, microcontroller,etc)

I did a little googling during my lunch on the disc brake idea, it looks as if that could be a viable option.