chucky

Check out this prototype (not a design concept, but a real bike)

https://www.popularmechanics.com/tech...-genius-awards

Could be useful for designing a folder with a more compact fold (ie fold the frame inside the wheels).

invisiblehand

Or at least a travel bike: Pack stuff inside the wheel.

Urbanis

Fascinating!

kamtsa

It has two chainrings and chains to achieve the high RPM for that small driving wheel.

vik 

Looks like a crazy heavy frame and a lot of complexity just to get rid of the spokes in the rear wheel. Not sure it makes a ton of sense beyond looking cool.

Folder4life

Strange lookin people in the picture, haha. But a cool lookin bike!

ratdog

Don't know about everyone else, but I still see spokes.

mustachiod

would be cooler if the front wheel somehow matched the rest of the design.

upon closer inspection of rear wheel, i noticed this:

jur

The spoked bicycle wheel is an enormously strong structure. Ditching the spokes and putting the mass load at the top requires the hoop the have that strength. Much heavier for similar properties. And then the guide structure has to resist lateral forces too. It might be better to place the load right at the bottom - that would eliminate the problem of making the hoop strong enough to bear load, and much of the lateral load problem.

As an engineer I would not call this a tech step forwards - heavier, more complex, less rigid, and I can't imagine how hard it must be to fix a puncture.

As an exercise to teach a class of engineering students the finer points of mechanical design, and suitability of design, good.

RWBlue01

It is a neat idea. I like it.

chucky

To a lesser degree all the same could be said of monotube folding frames vs diamond frames, yet we use them because they are more compactable. The same applies here.

Also, as an engineer you should know that everything must be driven by specification. Light, simple, rigid, etc are all meaningless if it doesn't meet the required specification (such as folding into a volume of X cubic cm). The hubless spokeless wheel has the potential to meet a specification of compactability which the spoked wheel will never meet, no matter how light or simple or rigid it is.

brakemeister

those hubless wheels show up in the bike and also motorcycle field every couple years, just to be put in a drawer and being forgotten again. Than 10 years later voila a new way to boil water.
Nothing wrong with that, but a true designobject would be to design something viable ..... something which actually can be built AND used on a daily basis. To give designstudents free range to re-design old stuff with no parameters for actual use is a waste of time in my opinion.

thor

Bacciagalupe

It could, but it doesn't. I don't see how you are saving anything worthwhile with this setup.

At best you might have an aerodynamic advantage. However, this could easily be mitigated by higher friction and various drivetrain inefficiencies (see below).

Looks like the only viable way to get a decent gearing range will be with an IGH. This will add weight and, in most cases, either drivetrain inefficiencies or higher costs.

You lose the ability to adjust the rim; if it goes out of true, how do you fix it?

How long does it take to change a tire? Is that process easier or harder than a traditional spoked wheel? What do you hook the tire levers onto?

Won't any misalignment of the wheel result in more drivetrain inefficiencies, and possibly major friction and noise if a part of the rear wheel connects intermittently with the frame and/or gearing?

You lose the ability to attach a rear suspension. And what happens if the rear wheel hits a substantial bump, crack or hole? Is the wheel more or less rigid than a spoked wheel? Is it more or less comfortable? A designer can alter those characteristics by adding or reducing the number of spokes, what about with this wheel?

The inner rim also has teeth, which will wear out long before the rest of the wheel. Is that a replaceable part? How do you clean it? How do you replace it? (It doesn't look field-repairable.) Also, as the inner rim teeth get dirty, your drivetrain loses efficiency.

The frame itself, while a neat design object, clearly has numerous challenges. The large flat surface area will create tons of drag in a crosswind, and the saddle offers zero height adjustment. 8 pounds is twice the weight of a steel diamond frame.


Or to put it another way: What are the problems with a spoked wheel that are resolved by the spokeless wheel? Are the problems significant enough to justify the compromises involved in this design?


Yeah, not really seeing that as the case. Spoked wheels can already get very compact (e.g. Brompton). You won't want to pack much "inside" the wheel, since the inner rim is likely to get dirty and you could damage the teeth. You might, at best, save about 1" of lateral compactness if you fit wheel-to-wheel.

It is possible that future iterations will resolve some of the issues. Also, the only way to truly determine if this is going to work and can be improved is by building a few prototypes and using them.

Unfortunately it looks to me like it was developed by a bunch of engineers who don't actually ride bicycles, and decided to solve a problem that doesn't exist. I don't think there will be many direct benefits from this setup.

chucky

Here's a parameter: make the no compromise smallest possible folding bike. No one has figured out how to boil that pot of water yet and with attitudes like yours no one ever will.

You are saving space. The Brompton uses a 16" wheel to fold to the size larger in extent than a 20" wheel. With a spokeless wheel it's possible to design a bike with a 20" wheel which folds the same size or smaller. That's a 20% improvement, which is far greater than the speed increase you'd get from losing 4 pounds.

I agree that this particular bike doesn't solve anything, but the advantages of a spokeless wheel for folding bike design are obvious.

Do you worry about damaging the teeth on the chainring of a Brompton? Or a Dahon? Clearly a spokeless wheel has many disadvantages, but your objections to the clear and apparent advantages are thoughtless and inane.

invisiblehand

I thought you liked the ride of larger wheels Bac. Seems to me that a fold that effectively uses that space inside the wheel lets one use larger diameter wheels.

brakemeister

[QUOTE=chucky;11476502]Here's a parameter: make the no compromise smallest possible folding bike. No one has figured out how to boil that pot of water yet and with attitudes like yours no one ever will.

have you actually read what I was writing ?
or is all that wisdom about tude just spilling out by itself ?
Thor

stevegor

The ability to pause and truly consider another's point of view is a gift enjoyed by very few.
The ability to apply another man's knowledge to your own is also a gift enjoyed by very few.
I have lived long enough on this earth to pause, consider and apply greater knowledge than my own to my own.

Sermon is now over........ back to the rigorous arguments..... I love it!!

Bacciagalupe

Sorry, but this design won't do it.

When you look at a pair of spoked wheels, they can actually fit quite close together. It's highly unlikely you can exploit the new space opened up by losing one or both sets of spokes.

Even under optimal circumstances, you're just creating a whole new set of compromises: More maintenance, fewer suspension options, more weight, and very likely a loss of performance.


1) Smaller wheels actually ride faster, due to better aerodynamics.
2) Aerodynamics are highly counter-intuitive. I would assume the spokeless wheel will have less drag, but it's unwise to say for certain until you test the design in a wind tunnel.
3) Unless you have some way to pack the frame inside the wheels -- unlikely with larger wheels, virtually impossible with smaller wheels -- you aren't likely to get as compact as a Brompton.


I'd say I am slightly concerned about how low a 16" or 20" bike's drivetrain is to the ground, and did have some mechanical issues which might have resulted from the lack of clearance.

However, it is not "inane" to point out that the spokeless wheel almost certainly requires more maintenance, will be harder to clean, can't use suspension, is heavier, and may result in a less efficient drivetrain. Nor is it bad form to ask what problems are resolved by this new design that are worth its compromises.



I do prefer larger wheels, but I don't think you will really save any space here.

More to the point is that in this case, I'm reasonably certain that the goal was not "build a better bicycle," it's "build something neato for a class." If this design solves some issue associated with spoked bicycles, I have no idea what those problems could possibly be, let alone how this design results in an overall net improvement for bicycle design.