Motor doping thread

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Re: Re:

GreasyChain said:
There was no evidence of a working hub motor. Just as there is nothing more than some weirdo's fantasy about using magnets in the wheels and elecromagnets in the chain stays, or possibly the brakes to drive them.

Putting a motor inside the bike for a professional is pointless. Added weight, added drag, high probability that the thing will either jam or go off at the wrong time and there is no possibility of getting away with it when you are inevitably caught.

Face facts. It's all bollocks.
Added weight? There's a minimum weight requirement for bikes and it's extremely easy to go below it with a high-end road bike, so just add a motor and shave off weight from other components and you're still at the 6.8kg limit.

Added drag? For a motor concealed inside the frame or the rear wheel?

The only thing that's all bollocks is the nonsense spewing out of your fingertips.
 
Jul 15, 2012
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Re: Re:

ScienceIsCool said:
...

Pray tell why you couldn't get 25-40 Watts out of a hub motor.

John Swanson
I tried.

Call it a failed effort to show that it can be done. I tried but couldn't.
I then urged you to try. Please do.

So far, I'm the only (?) one here that has done some real engineering using actual dimensions and adressing the packaging restraints.
If you claim that it can be done, give us a concept. Describe how much torque you envision should be produced and how the gearbox should be configured. Continue with the magnetic flux, the magnets type/size/location. How many ampere-turns do you need and how far would you push the current density?

Real numbers. No five minute google search with links to generic products.
 
Re: Re:

Nicko. said:
ScienceIsCool said:
...

Pray tell why you couldn't get 25-40 Watts out of a hub motor.

John Swanson
I tried.

Call it a failed effort to show that it can be done. I tried but couldn't.
I then urged you to try. Please do.

So far, I'm the only (?) one here that has done some real engineering using actual dimensions and adressing the packaging restraints.
If you claim that it can be done, give us a concept. Describe how much torque you envision should be produced and how the gearbox should be configured. Continue with the magnetic flux, the magnets type/size/location. How many ampere-turns do you need and how far would you push the current density?

Real numbers. No five minute google search with links to generic products.
It would be wonderful if you could post some photos of your laudable engineering attempt.
 
Jul 5, 2009
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Right. And in the past, I've talked about how you'd design a system.

First up, you need to figure out what motor technology is best suited to the application. My suggestion was to go low speed, high-torque so that you don't need much by way of gearbox reduction. My conclusion was to start by using a stepper motor, since they have the largest torque near stall.

Second, what is a stepper motor capable of? Can we theoretically get 40 Watts into the volume of a hub? If not, there's no point in continuing. In my career, I've been exposed to steppers a fair bit and my experience has been mostly with Oriental. So let's take a look at a few of their spec sheets. Here's a motor that's 40mm x 90mm and includes a 5:1 planetary reduction box. At 300 rpm, you're getting 1.3 Nm. That works out to 41 Watts. Convenient!

http://catalog.orientalmotor.com/item/rkii-series-5-phase-stepper-motors/42mm-rkii-series-5-phase-stepper-motors/pke545ac-ps5

So that works out to 40 Watts in a 100,000 m^3 volume. The volume to work with in your diagram is about half that. So naively, we can put a 20 Watt motor in there.

Not a bad start! It's not completely infeasible so we don't have to abandon the project.

The good news is that off-the-shelf parts have thick cases, mounting points, etc, and are generally built for heavy duty applications. In other words they can be stripped down. Also, as I have shown before, if all you need is a 5:1 reduction, you can use an incredibly small planetary gear 3D printed out of nylon. Might only last a week, but... Anyways, so there's lots of room to improve. I'd start my investigation by buying one of these plus a motor controller and stripping it down to reverse engineer the thing and get some insights on how they designed it.

At this point, you THEN start to design a system of your own. Probably keep the off the shelf motor controller, but fire up the CAD and design a motor that meets the physical constraints. Get someone to fab the parts and then bench test. Rinse and repeat until you've got a motor that meets spec. Hopefully at the same time someone is tackling the electronics and shrinking the motor controller.

Remember that you also have the option of outsourcing this phase by contracting some small Asian manufacturer to design one for you. Potentially less risk in terms of budget and schedule but you do lose some control.

So if you want me to sketch you a design, you're out of luck. The basic legwork hasn't been done yet. But I have shown a starting point and have given some calculations to show that any effort put into this wouldn't be wacky.

John Swanson
 
There is a guy here who used a Vivax seat tube/BB motors last year just for the sake of seeing what the possibilities are. He was very open about it so he wasn't trying to fool anyone. I have not talked to him or anyone else who knows what his data looks like 12 months later. The only thing I did hear third hand was that testing it in the stand, you could hear it, but riding in a group on the road you couldn't hear it.

Like I've posted, this type of motor is easy to see simply by removing the seat post.
 
Re:

veganrob said:
Are you sure of that? It could have been a Shimano rim with a different hub. If you have some close up pictures of the offending wheels/hubs that would be nice.
Froome's bike review video here:

http://www.cyclingweekly.com/videos/pro-bikes/tour-de-france-bikes-chris-froomes-pinarello-dogma-f10-video

Rear hub at 50 seconds.

Of course, people can claim that he may have been using different hubs/wheels in the race, but from memory I don't think he was and I would say that the onus would be on them to show that was the case. I think it's the kind of thing that would get picked up on by observers/commentators etc.

Bikes in the start (in guessing?) area. Hard to see but the front certainly looks like a DA hub and the rear doesn't have an oversized hub on it.

Photo from the PDBF stage which catches the rear hub and looks like a DA hub, or at least of a similar size:



I think Corima hubs are bigger, afraid I don't know about anything else.
 
Jul 15, 2012
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Re:

ScienceIsCool said:
And here's the motor without the gearbox: http://catalog.orientalmotor.com/item/rkii-series-5-phase-stepper-motors/42mm-rkii-series-5-phase-stepper-motors/pke545ac

So the gearbox takes up half the volume in this case. This improves our situation quite a bit because now, naively, we can fit a 30 Watt motor in the diagram provided and still keep 25% of the volume for a 5:1 gearbox.

John Swanson
See, I asked you to not do a 5 minute google search to find a generic product you could 'scale' to a road hub...

Since you seem to agree that there must be a gearbox, you do realize that the "output shaft" (the axle that meets the dropouts) must exit the stator (the hub shell) on both sides? That means the rotor must be hollow...

The generic planetary gear that sits on one side of the motor will not work. Neither will some through axle on the side of the motor.

'naively' won't do here.

edit: apply 'rotor', 'stator', 'output shaft' arbitrarily. the fast spinning part must be 'inside' and 'between' the slow moving parts.
 
Jul 15, 2012
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Re:

veganrob said:
Nicko. Why are you using a Shimano DA hub? There are much bigger ones on the market to conceal a motor.
The winner of Paris-Roubaix 2017 was under scrutiny. Some argued a hub motor, I saw a Shimano hub and said 'no way'.

IMO, one can only argue hub motor if the hub is BIG.
 
Jul 5, 2009
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Re: Re:

Nicko. said:
veganrob said:
Nicko. Why are you using a Shimano DA hub? There are much bigger ones on the market to conceal a motor.
The winner of Paris-Roubaix 2017 was under scrutiny. Some argued a hub motor, I saw a Shimano hub and said 'no way'.

IMO, one can only argue hub motor if the hub is BIG.
Because you based that on nothing. I just showed that a naive implementation puts 30 Watts in that envelope.

John Swanson
 
Oct 16, 2010
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@Nicko, To suggest the design problems you point out present insurmountable obstacles to a group of highly paid top engineers, that's naive at best.

But it's good to hear you now do think a rear hub motor is possible. Thats progress.

By the way, one might consider taking Roglic' 2016 strade bianchi rear hub as a starting point for more detailed calculations.
Roglic is by far the most plausible case study for a rear hub motor, i.e. the case for which most evidence exists.
 
Re: Moto-fraud: first rider caught

Sky don't have the option to use others hubs or rims with the latest Shimano sponsorship like they used to have. You used to see them riding all sorts of custom-built HED rims, Enve Composites rims, Zipp rims, Tune hubs, Chris King hubs depending on stages. They're now locked into Shimano wheelsets, but then there's no gain to be found using bespoke wheels now because Shimano offer wheelsets right up there on weight and aerodynamics which they didn't back in 2010-2014 during the old sponsorship agreements and why Sky put in the equipment clause previously.
 
Jul 15, 2012
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Re: Re:

ScienceIsCool said:
I just showed that a naive implementation puts 30 Watts in that envelope.

John Swanson
I think I have asked you nicely seven times now to show how you would generate the torque, configure the gearbox, handle the temperature, interact with the freewheeling cassette, avoid public breakdown, etc etc, all within a non-conspicuous road hub.

You keep doing a volumetric scaling of generic motors, never adressing the details (where the devil resides).

edit: removed insult. sorry.
 
Jul 15, 2012
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Re:

sniper said:
@Nicko, To suggest the design problems you point out present insurmountable obstacles to a group of highly paid top engineers, that's naive at best.

But it's good to hear you now do think a rear hub motor is possible. Thats progress.
For you to suggest that I'm not a highly paid top engineer myself is naive. Period.

Your memory fails you. Go back a few hundred posts and read what I think about possibilities regarding motor fraud.
If I was a professional cyclist I would probably be cheating with motors...
 
Re: Re:

Nicko. said:
ScienceIsCool said:
I just showed that a naive implementation puts 30 Watts in that envelope.

John Swanson
I think I have asked you nicely seven times now to show how you would generate the torque, configure the gearbox, handle the temperature, interact with the freewheeling cassette, avoid public breakdown, etc etc, all within a non-conspicuous road hub.

You keep doing a volumetric scaling of generic motors, never adressing the details (where the devil resides).

edit: removed insult. sorry.
Are you as skeptical about the possibility of a hub motor in a PowerTap hub?
 
Interesting. Someone is arguing that something isn't possible for a whole bunch of reasons, each of which is demanded to be proven false or else the person on the other side isn't to be trusted. Kinda like the pro tobacco lobby did, picking some spurious stat and claiming because the other side can't prove it false, therefore they are completely wrong.

Motors exist in bikes. Scaling it is simply a dollar cost issue.
 
Oct 16, 2010
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Re: Re:

Nicko. said:
sniper said:
@Nicko, To suggest the design problems you point out present insurmountable obstacles to a group of highly paid top engineers, that's naive at best.

But it's good to hear you now do think a rear hub motor is possible. Thats progress.
For you to suggest that I'm not a highly paid top engineer myself is naive. Period.

Your memory fails you. Go back a few hundred posts and read what I think about possibilities regarding motor fraud.
If I was a professional cyclist I would probably be cheating with motors...
Fair enough.

Edited by King Boonen: Do not state something as fact when it is not.
 
Oct 16, 2010
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Re:

Random Direction said:
Interesting. Someone is arguing that something isn't possible for a whole bunch of reasons, each of which is demanded to be proven false or else the person on the other side isn't to be trusted. Kinda like the pro tobacco lobby did, picking some spurious stat and claiming because the other side can't prove it false, therefore they are completely wrong.

Motors exist in bikes. Scaling it is simply a dollar cost issue.
bingo.
 
Jul 15, 2012
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Re:

Random Direction said:
Interesting. Someone is arguing that something isn't possible for a whole bunch of reasons, each of which is demanded to be proven false or else the person on the other side isn't to be trusted. Kinda like the pro tobacco lobby did, picking some spurious stat and claiming because the other side can't prove it false, therefore they are completely wrong.

Motors exist in bikes. Scaling it is simply a dollar cost issue.
You got that backwards, we're trying to prove something is true.
I can't but I'd like someone to show how it can be done. Kinda like Archimedes...

edit:spelling
 

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