innovative hub motor design epiphany.

[lbz5mc12]

Okay let me explain. We all know how much of a pain in the butt hub motors and broken spokes can be. Well I think I've hit upon a solution. Why not thread the hub motor into a mag rim? Instead of eyelets on the hub for the spokes, make it a solid thick piece of metal and thread the top of it. Then you just build a mag rim with a hole wide enough to except the hub and thread the hub into the rim. Then you just need some kind of keyed mechanism to lock the hub in place. This would be to keep it from coming un-thread during use but also to prevent someone from stealing it. I figure you could use mag rims anywhere from 20" on up to 29". I don't think it would work with a 16" wheel unless it's a small geared hub.

This would also allow the user to easily switch out his/her rim sizes without having to completely rebuild the wheel. Just order a new size rim, pop the hub out of the old one and thread it into the new one. Go from building a wheel that could take hours down to just changing it out in a few minutes.

Yes I know that hub motor cases are built out of 2 separate halves. The manufacturer would have to fully assemble the hub and when it's sandwiched together, thread the top of it and "mark" it so that if it's ever taken apart it gets put back together so that the thread lines up.

The rims could be built out of aluminum, titanium, carbon fiber etc. No more broken spokes and tedious wheel builds.

Sorry to edit my post but I just had an improvement idea. How about making the hub into a big freewheel? Brushless hub motors cause drag, what if the ring of threads inside the mag rim were a big freewheel. You reverse thread the hub so that it threads in in the direction it drives. When the motor's engaged the wheel spins and when its not the mag freewheels over the hub so there's no drag from the motor.

 

[Chalo]

How would you true a mag wheel? Because if you can't, you have to make the wheel so massive that it is unlikely to bend in normal use.

Have you noticed that all the mag-type wheels for bicycles are heavier, more expensive, and much weaker pound-for-pound than wire spoked wheels of like materials? Skyway and Aerospoke have been doing the pedal-bike version of what you suggest for decades now. They have a few devotees, but not many.

The idea has some merit for rims that are close to the diameter of the corresponding hub motor. A spline or bolt-circle interface would be better in this case than a thread on the motor OD.

 

[heathyoung]

Golden motor magic pie - already exists. 20" size was popular here for a while due to the torque you could wring out of it.

 

[lbz5mc12]

I know golden motor 20" wheel exists but it's one piece. Chalo, would my idea work with a spoked rim?

 

[John in CR]

It already exists and is called Hubmonster, the best hubmotor available for under $5,000 .

Here's one on my bike with the stock 13" scooter rim along side is a 16" motorcycle mag wheel I cut the hub and brake out of to adapt it to the motor. No worries about truing just like you don't true any wheel with a proper rim, but once you get the tire on you do have to balance it which is quite easy to do manually.


Here's what the stock 13" rim with the lowest profile tire available looks like next to a 20" bicycle wheel, and as long as you aren't pushing a total load (you and bike) over 175kg or so, then going to the biggest street tire available pushes the OD to about 22".


I much prefer the bolt on rims instead of the built on, because with built on you have to put the tire on by hand, which is no picnic. With the bolt on I just bring the rim and tubeless tire to the any tire repair shop to install for $2. It's also great to have a DOT approved tire, so no worries on the road even at highway speeds....Only 1 flat in 6 years. I picked up a nail near a construction site and was still able to ride it home. Being tubeless I was able to just pull the nail and plug the hole, which is a simple as tire repair gets. Plus if you shop around, you can find a real tire for less than many pay for high maintenance quick wearing bike tires that go flat by themselves in a relatively short time.

 

[Chalo]

Each wheel of my motorcycle weighed more than any of my bicycles. It's easy to see that's where you would take the state of our particular art, John, but fortunately opinions differ on this.

(Oh, and every so often I would bash in a rim on my motorcycle and have to replace it, because it could not be trued.)

 

[John in CR]

Each wheel of my motorcycle weighed more than any of my bicycles. It's easy to see that's where you would take the state of our particular art, John, but fortunately opinions differ on this.

(Oh, and every so often I would bash in a rim on my motorcycle and have to replace it, because it could not be trued.)

Yes fortunately opinions do vary, since for some strange reason you aren't able to see that a more useful, practical, economical vehicle is somewhere between the current state of ebikes and emotos/ecars and if we wait for BIG to develop them we're screwed.

Regarding your busted rims, that obviously has to do more with riding in a safe manner and/or state of intoxication from whatever substance than the wheel itself. Sure I managed to mess up a few rims way back when I was 15/16, but since I started commuting on motos in 1995 thru to ebikes in 2008, I ride with sufficient care and focus that I don't hit holes or debris remotely capable of damaging a bike rim, much less a heavy duty mag wheel. Those who ride their stuff with less care should be aware that spoked wheels may be a better option for them for the same reasons mag wheels aren't used in motocross.

FWIW regarding wheel weight, I've tried discussing the idea of smaller bike friendly versions of their high quality motors on many occasions, but they simply won't accept that there's a market for premium quality hubmotors, so those who think like you do end up stuck paying premium prices for generic quality motors.

 

[lbz5mc12]

Yeah I also was thinking about the bolt on idea to. I just think it would be easier and more interchangeable if the hub were to be threaded into the mag. One thing I forgot to mention about Chalo's original reply, They're hub motors, if we were too concerned about the weight of the wheel, we wouldn't be using hub motors in the first place.

 

[Chalo]

A hub motor does something for you a regular lightweight bicycle hub doesn't; but a pig-heavy mag wheel doesn't do anything more for you than a lightweight bicycle wheel already does.

 

[lbz5mc12]

I'm already gorilla-heavy so weight's not a big issue to me ha ha ha.

 

[spinningmagnets]

Since John travels at high speed on Costa Rican roads, I believe his suggestion is excellent for that application. And since Chalo rides fairly smooth roads, his light-weight rig is appropriate for that application.

As to the OP's idea, I've done some fun experiments that didn't work out, but whether they worked or not...it was fun. one of the great things about bikes (and even E-bikes) is that any wild idea you might get is fairly possible for the average guy to test in his garage (or a friends garage...). I recommend you focus on having fun in your experiements, and then let the chips fall where they may.

 

[lbz5mc12]

Finally, a voice of reason.

 

[John in CR]

I'm already gorilla-heavy so weight's not a big issue to me ha ha ha.

Yeah, but Chalo weighs more than both of us, yet he worries about grams when it comes to a bicycle. :? I've heard of weight weenies, but Chalo is his own term.

I don't know Spinning Mags, as much as people worry about hitting holes with the mag wheel I think maybe the roads around where I live are better. Sure there are bad roads, but I can always find a route to anywhere I'm going (except maybe way out in the sticks like where Harold lives) with nice smooth roads. Very few roads with shoulders, so cyclists and slow ebike and stinkbike riders are insane AFAIC.

Chalo,
Yes heavier than spoked, but I wouldn't call these alloy mag wheel's pig heavy. BTW these "pig heavy mag wheels" actually do something that no bicycle wheel can. That is they fit on the best hub motor in the world available for under $10k. Oh and that well over $10k beast weighs almost as much and only produces 1800W continuous and 5580W peak for up to 72 seconds. I only call it better because it's over 98% efficient and is The motor to use in solar challenge competitions.

 

[Chalo]

When you're talking donut wheels for hub motors, that's another thing. Those barely have room for spokes anyway, and the mass of a mag or stamped steel wheel that small isn't a big deal. What is a big deal is the frankly shitty qualities of a small diameter wheel when it comes to ride quality, rolling resistance, behavior over bumps, tire wear, traction....

Mag wheels for full diameter (26" and larger) tires are more vulnerable to irreparable damage, heavier, and more expensive than conventional wheels. That's why they are usually limited to clown fixie bikes and the like.

 

[John in CR]

Chalo,

I have one that is a 16" moto mag wheel, so that's getting closer to what you think is a respectable wheel size. I do realize that it's more susceptible to damage than a spoked wheel, but with the magnets mounted in the shell of the motor I haven't been able to figure out a way to add spoke flanges or put spokes through the shell. Maybe you've seen a method that will work. I could actually bolt on a spoke flange to the cover side pretty easily, but the other side doesn't come off. Do you think straight spokes (no 90° angle at the head) could work with a cast steel shell, or are the forced to great for cast steel and I risk pulling one out and breaking the cast shell thereby ruining the motor?

What's a clown fixie anyway? Why would they put mag rims on a fixie? I thought fixies were supposed to be minimalist and light, and as simple as a bike can get.

 

[lbz5mc12]

But you have to remember to take into account the width of the tire and whether or not the bike has suspension. Last I checked wider tires and suspension tend to limit the damage done to rims via impacts during the course of regular use.

My whole idea is based around ease of use and the ability to utilize different size rims without having to rebuild the whole wheel. Even if the rim were to get damaged and become useless, it would be super easy to replace the rim.

 

[John in CR]

...My whole idea is based around ease of use and the ability to utilize different size rims without having to rebuild the whole wheel. Even if the rim were to get damaged and become useless, it would be super easy to replace the rim.

Yes, that's exactly what I have. In my first pic either of the wheels will bolt directly to the motor.