Motor doping thread

[Hawkwood]

Re: Re:

Thought you might enjoy this. Seat tube motor in a road bike, back in the (looks like) 1970s.

https://youtu.be/9YXDL7P7_zY

Moto doping has been going on since 1979 and the 1st 'bust' was in 2016. Good job UCI.......

Freewheel in the chainset, so you stop pedalling and the chainrings keep going round, might that not have been a bit of a give away?

No one is looking!

Some people thought it was impossible that 'moto doping' was happening, as it would be noticed, pros were somehow above it, noise, wheels turning when they shouldn't etc etc......but then BOOM, bike found with a motor at a UCI WC event.

Sorry but when 200 riders are moving in a group who is looking for a motor in the peloton?

I thought the spectators were looking, the tv cameras etc. A freewheel in a chainset would stand out like a sore thumb. There's the physical difference to the chainset to begin with, and then the cranks motionless while the rings spin. This would be the least likely way of motorising a bike so that it can't be spotted, apart from the Copenhagen wheel design that is.

 

[Benotti69]

You wont find many spectators watching hubs, cranks or other bike parts as a race passes.

 

[GJB123]

Re: Re:

As to 1. You don't seem to understand, we are not talking detection by the UCI alone, we are talking about a bike that would look so different that any TV viewer would have to wonder WTF is going on. Trust me coils wrapped around the outside of seat stay would finitely attract attention from all and everybody. Not least you yourself would have pictures up in this thread within a split second.

the guy in the gazzetta doesn't make any mention of coils wrapped around the outside of the seat stay, though.

As to 2. You really do not seem to grasp the physics do you? The fact that someone with a working brain, Google and reasonable knowledge of physics can calculate that in practice it will probably not work doesn't mean anything. You can't change basic physics by throwing EUR 500,000 at it. Physics aren't corrupt.

sure, this level of physics is way above my paygrade.
but the gazzetta guy thinks it is possible.
i don't see any clear-cut motivation for that guy to invent stories like this.

the fact that jyl can't get his head around the physics doesn't mean a group of specialists with a royal budget can't either.

with enough of a budget and enough specialists working on it, one could get some not-too-conspicuous, wheel-driven system working. It would be grossly insulting to the state of present-day physics and sports technology to suggest one can't.

Sometimes you really are beyond believe. There were links provided to opinion of experts who say it is practically impossible withut making serious adjustments to the bikes. I know Gazetta doesn't mention coils on the outside of the stays, duh. That would be visible for everybody, that is just the point. The point further being that with coil on the insides of the stays it becomes even lees viable as an option.

 

[GJB123]

Re:

You wont find many spectators watching hubs, cranks or other bike parts as a race passes.

Rubbish. A hub that is half the size of the total wheel will stand out like a sour thumb. As would someone freewheeling all the while accelerating. You guys are hilarious.

 

[Benotti69]

Re: Re:

You wont find many spectators watching hubs, cranks or other bike parts as a race passes.

Rubbish. A hub that is half the size of the total wheel will stand out like a sour thumb. As would someone freewheeling all the while accelerating. You guys are hilarious.

That's why so many people on the side of the road caught so many riders and yet we see so many making these motors and only one silly Belgian U23 rider caught. HAHAHA, yes good joke no, very funny ya!

 

[GJB123]

Re: Re:

nice vid of the Copenhagen Wheel here:
https://www.superpedestrian.com/

it was patented by MIT in 2009.
we're 7 years on from that.

But 7 years on, $6.1m spent in development costs, and at August 2015 not a single wheel shipped according to this: http://www.bikebiz.com/news/read/copenhagen-wheel-is-nearly-ready-to-roll-again/018302
Plus it relies on oversized hubs...

ok, thanks. good to scrutinize this stuff.
Of course that doesn't mean the technique is not available to teams like Sky.
And it goes to show that we shouldn't stare blindly at electromagnetism.
A variety of motorization systems have been, are, and will be available, especially at the high end.
Teams like Sky, guys with big contracts like Cancellara and Hesjedal.
Who's using what is going to be anybody's guess. Like with old school doping.
Although, based on the footage we can make 'educated' guesses.
If Hesjedal used anything, it was a wheel drive system.
Cancellara -> hub-based "silent pro".
Froome 2013? My guess is a wheel drive system along the lines of the Copenhagen wheel. Funny thing is, the l'Equipe article last year spread rumors about Sky riders using their powermeter to activate some motorsystem.
It would nicely fit with the Copenhagen system.

Amateurs and continental pro's: some variant of the silent pro for simple financial reasons.

When will you get it into your head that motoring the wheel is highly impractical and therefore unlikely, The motor in the downtube is well known for quite a while and much simpler to achieve. Even using some high-powered batteries that may be only Sky have access to. And why in the world would Sky spent nigh on 0.5 million or more on some super duper moto wheel that would stand out like a sour thumb when they can just shove a motor in the downtube and have their buddy Cookson look the other way. Occam's razor.

And as for Hesjedal using a moto driven wheel. NOT. Do you see a humongous hub in his back wheel?

 

[GJB123]

Re: Re:

You wont find many spectators watching hubs, cranks or other bike parts as a race passes.

Rubbish. A hub that is half the size of the total wheel will stand out like a sour thumb. As would someone freewheeling all the while accelerating. You guys are hilarious.

That's why so many people on the side of the road caught so many riders and yet we see so many making these motors and only one silly Belgian U23 rider caught. HAHAHA, yes good joke no, very funny ya!

The motor in downtube is not easily detectable, so that people on the side or on TV didn't notice is not strange at all. What is it exactly that you don't understand about that? Am I so clever or are you so plain stupid?

A hub the size of big frisbee stuck in the middle wheel most certainly would get noticed by each and everyone. Suggesting otherwise is plain ridiculous. Now if you were to claim that a hub can be put in a disk wheel used for time trialling I might start listening, because at least it would some sense.

 

[Hawkwood]

Re:

jyl,

2. you spent how much time making this quite brilliant set-up? maybe a day? with what budget? no budget?
now imagine a group of five, six sports scientists working on this for months on end, with, say, a budget of 500,000 euro, and lots of prospects for extended funding. Good money. Lots of time.
Lots of expertise & know-how. Lots of motivation. State of the art tecnhology. Lots of omerta.

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

 

[GJB123]

Re: Re:

jyl,

2. you spent how much time making this quite brilliant set-up? maybe a day? with what budget? no budget?
now imagine a group of five, six sports scientists working on this for months on end, with, say, a budget of 500,000 euro, and lots of prospects for extended funding. Good money. Lots of time.
Lots of expertise & know-how. Lots of motivation. State of the art tecnhology. Lots of omerta.

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

Priceless! No doubt sniper cs will come back strongly on this why Sky can outfox MIT.

 

[Hawkwood]

Re: Re:

You wont find many spectators watching hubs, cranks or other bike parts as a race passes.

Rubbish. A hub that is half the size of the total wheel will stand out like a sour thumb. As would someone freewheeling all the while accelerating. You guys are hilarious.

That's why so many people on the side of the road caught so many riders and yet we see so many making these motors and only one silly Belgian U23 rider caught. HAHAHA, yes good joke no, very funny ya!

Let's be clear here having a freewheel in a chainset is just about the most ridiculous way you could motorise a bicycle and get away with it, but you think it's a serious possibility?

 

[Hawkwood]

Re: Re:

jyl,

2. you spent how much time making this quite brilliant set-up? maybe a day? with what budget? no budget?
now imagine a group of five, six sports scientists working on this for months on end, with, say, a budget of 500,000 euro, and lots of prospects for extended funding. Good money. Lots of time.
Lots of expertise & know-how. Lots of motivation. State of the art tecnhology. Lots of omerta.

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

Priceless! No doubt sniper cs will come back strongly on this why Sky can outfox MIT.

If I had lots of money, and really wanted to motorise a wheel, who would I got to with $6m, why MIT of course! If some UK university has cracked this then it will want to publish to improve its research ranking.

 

[poupou]

Re: Re:

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

5.9kgs for a 300Watts and cheap motor!
What about a 50watts and expensive motor made of titanium and other expensive material?
What about the battery in the frame, and the power transmitted by induction ?

 

[blackcat]

Re: Re:

jyl,

2. you spent how much time making this quite brilliant set-up? maybe a day? with what budget? no budget?
now imagine a group of five, six sports scientists working on this for months on end, with, say, a budget of 500,000 euro, and lots of prospects for extended funding. Good money. Lots of time.
Lots of expertise & know-how. Lots of motivation. State of the art tecnhology. Lots of omerta.

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

and those scientists can leave MIT and get millions a year on Wall Street, or they can go to Microsoft and Google and work in those super smart divisions with crack mathematicians for the dough and intellectual stimuli

 

[GJB123]

Re: Re:

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

5.9kgs for a 300Watts and cheap motor!
What about a 50watts and expensive motor made of titanium and other expensive material?
What about the battery in the frame, and the power transmitted by induction ?

You have read the explanations why this last solution remains unlikely in practice?

 

[Farcanal]

Re: Re:

You sort of answered this yourself when you highlighted the Copenhagen Wheel. The Copenhagen Wheel project is being run by a team of 20 scientists and designers from the Massachusetts Institute of Technology, a World top 5 university. It's taken the team 7 years and more than $6.1m to develop a motorised wheel that weighs 5.9 kgs and might just have gone on sale (not in stock when I did a trial order). Perhaps someone should contact the MIT team and ask whether the rim theory is really a goer.

5.9kgs for a 300Watts and cheap motor!
What about a 50watts and expensive motor made of titanium and other expensive material?
What about the battery in the frame, and the power transmitted by induction ?

You have read the explanations why this last solution remains unlikely in practice?

It really is pointless for Hawkwood and you to keep banging your head on these bricks that don't even have a good enough grasp of 10th grade physics to understand that all electric motors are electromagnetic whether inside a frame or split between the frame and the wheel. Trying to explain field strength, direction and electromotive force is entirely wasted on people who believe that enough money can change the laws of physics and who think that Sky/BC/Cookson is an anagram of conspiracy. Just point them towards the new series of the X-files. It's more suited to their mentality.

 

[ScienceIsCool]

The MIT motor is what is called a "pancake" motor because it's shaped like a disc. They've been around forever and I'm guessing what the MIT team was doing is finding ways to get sufficient torque out of it. Much, much more likely is that a hub motor is being used. My guess would be potted windings on the axle and the hub shell, run at very high voltage from a battery powered controller tucked into the frame. The only trick would be making sure you get a decent electrical connection from the dropout to the hub. It wouldn't be geared, so the setup would be low speed/high torque rather than something like the Vivax which can run at high rpm. That kind of motor is much easier to make. And I have no clue if you could build this hub motor to actually look like a "normal" hub.

John Swanson

 

[jyl]

Good points all, here are my thoughts:

- The seatstays of current pro bikes are pencil thin, no room for an electromagnet big enough to matter. This is clear from the physics of magnetism, the field strength depends on the dimension of the coil and the distance from the coil.

- Embedding strong permanent magnets in the rim would increase the attractive force. However, the wheel will no longer spin freely. Even when the motor is turned off, the rim magnets will still be attracted to the iron core in the chainstay electromagnet, causing the wheel to have a ratcheting or stuttering sort of motion. That would be quite obvious when the bike is on a workstand, after a crash when the wheels should be spinning, and probably even when rolling the bike at low speed.

- A practical rim drive for motor doping does indeed have to be undetectable. Pro bikes get closely scrutinized. The riders look at other riders' bikes, they are riding inches apart in the peloton for hours each day. Mechanics monitor what the competition is doing, and they often work on bikes in the open. Fans check out the bikes up close, between getting autographs. The cycling media takes close-up photos and does articles on "bikes of the bunch". Anyone can scan a bike, now that hidden motors are big news: thermal imagers cost $1500, infrared thermometers $50, EMF meters (magnetometers) $50. That's even if you think the UCI isn't actually scanning for motors, that the tablets are non-working dummies, the x-ray machines are never turned on, that when mechanics are called into the tent to remove seatposts and cranks, everyone just drinks coffee and plays charades.

- The Copenhagen Wheel is fine for a grocery or commuter bike. I think you'll get noticed trying to slip one into Cavendish's aero Cervelo.

The basic point some of you are making is, with unlimited money and engineers, can't we make anything that we can dream up?. Sorry, no. Otherwise we'd have tractor beams, transporters, deflector shields, phasers, levtiating cars, and so on. At the end of the day, physics constrains what we can do, and electromagnetisn is about as basic as physics gets.

 

[sniper]

good posts with the odd exception of farcanal and gjb123 who seem to mistake normal discussion/debate for some kind of mudthrowing competition and would prefer everybody to just move on and not learn anything here.

@hawkwood: touche, well spotted. But regardless, it took me a 5 minute google search to come up with that Copenhagen wheel. And while doing that I found a host of other experimental stuff, mostly on mountainbikes. I never suggested Sky or Hesjedal are using any of that stuff.
The point I made (explicitly) was that we aren't anywhere near an exhaustive overview of what is possible in terms of wheel-drive systems.
So to suggest that, because we don't know what Sky/Hesjedal could be using, we should just move on and assume they're not using anything, that's just silly.
(to be sure, that's not your suggestion, but it's what gjb123/farcanal seem to have on the agenda)

@Scienceiscool, pardon my ignorance:
am i correct that the system you describe above would involve only wheel drive?
so no moving cranks?

 

[GJB123]

Re:

good posts with the odd exception of farcanal and gjb123 who seem to mistake normal discussion/debate for some kind of mudthrowing competition and would prefer everybody to just move on and not learn anything here.

@hawkwood: touche, well spotted. But regardless, it took me a 5 minute google search to come up with that Copenhagen wheel. And while doing that I found a host of other experimental stuff, mostly on mountainbikes. I never suggested Sky or Hesjedal are using any of that stuff.
The point I made (explicitly) was that we aren't anywhere near an exhaustive overview of what is possible in terms of wheel-drive systems.
So to suggest that, because we don't know what Sky/Hesjedal could be using, we should just move on and assume they're not using anything, that's just silly.
(to be sure, that's not your suggestion, but it's what gjb123/farcanal seem to have on the agenda)

@Scienceiscool, pardon my ignorance:
am i correct that the system you describe above would involve only wheel drive?
so no moving cranks?

Easy cop out yet again. I very much want to learn things here and hope others do as well. It is just that you seem to ignore any message that doesn't fit your narrative and just keep harping on as nothing was said, told or explained (and explained quite well at that) at all. In other words you do not seem to learn anything.

As asked before, why on earth would Sky spend millions on a driven wheel that seems far-fetched at best and of which it was quite clearly explained that it would not be probable in practice, if they can also use a simple motor in the downtube and buy off any checks by the UCI etc.? It just doesn't make sense, you can see that, can't you?

 

[Farcanal]

Re:

good posts with the odd exception of farcanal and gjb123 who seem to mistake normal discussion/debate for some kind of mudthrowing competition and would prefer everybody to just move on and not learn anything here.

@hawkwood: touche, well spotted. But regardless, it took me a 5 minute google search to come up with that Copenhagen wheel. And while doing that I found a host of other experimental stuff, mostly on mountainbikes. I never suggested Sky or Hesjedal are using any of that stuff.
The point I made (explicitly) was that we aren't anywhere near an exhaustive overview of what is possible in terms of wheel-drive systems.
So to suggest that, because we don't know what Sky/Hesjedal could be using, we should just move on and assume they're not using anything, that's just silly.
(to be sure, that's not your suggestion, but it's what gjb123/farcanal seem to have on the agenda)

@Scienceiscool, pardon my ignorance:
am i correct that the system you describe above would involve only wheel drive?
so no moving cranks?

Nobody is just mudslinging. This thread is becoming nauseating with its repetition of factually correct posts followed by straw clasping comments trying to get around basic science with 'what might be possible with a huge budget?'. Whether its Sky or any other team that is the target of that sort of innuendo, all of them put together don't have the budget to change physics.

If somebody on here was arguing that EPO shouldn't be banned because it is just a placebo that gives no real benefit except for a psychological boost then he/she would correctly be rubbished wholesale for ignoring the science. No doubt some of the posters would be very sarcastic in their responses too. That is exactly what is happening in this thread, just because the science doesn't suit the narrative.

The 'rim drive' concept is a complete non-starter. When I read the report from Gazettta I had tears streaming down my face before the end. I have no idea what the guy's motivation is, probably just self publicity, but even if his system were to generate enough emf to turn the wheel the weight disadvantage at the rim would be huge (and remember the effect of inertia at the rim of a flywheel is proportional to the square of the radius).

The rider has to overcome that inertia for the rest of time he is riding it and, once it's battery is dead, the 'motor' turns into a generator (dynamo) which absorbs his energy like an induction brake. There is no way to put a clutch in that system. Now you might say that gives a good opportunity to re-charge the battery downhill but the efficiency losses would make it a very poor trade off.

 

[Maxiton]

You can do more miracles with electricity than chemistry, it’s also less damaging to your health. -- Industry "guru" of moto-doping

The new frontier is far more technologically advanced and ten times as expensive. It’s in the rear wheel: it costs 200,000 Euros, and there’s a waiting list of six months. -- Gazzetta dello Sport

The above quotes are from the article cited earlier. The industry guru, whoever he is, seems pretty convinced. I imagine that if you don't care about your health, you can do even more miracles with the two in combination.

Meanwhile, notice that the Gazzetta dello Sport reporter isn't conjecturing about whether these electromagnetic wheels are possible; he's saying they're already in production, and that the backlog for them is six months. He's also saying that they have a price, two-hundred thousand euros each. That can only mean they are in production and being produced at a profit. And at that price they are not being bought for grand fondos.

These things are always impossible. Until they're not. From 2010 I recall reading some very good responses to the question of bottom bracket motors that drew upon seemingly solid knowledge of engineering and physics, and that said such motors were, if not impossible, impractical. Some of these arguments were so compelling that the debate was pretty much at a standstill - until little Femke Van den Driessche showed up, teary-eyed, with her motor bought with parakeet money.

 

[jyl]

Re:

The MIT motor is what is called a "pancake" motor because it's shaped like a disc. They've been around forever and I'm guessing what the MIT team was doing is finding ways to get sufficient torque out of it. Much, much more likely is that a hub motor is being used. My guess would be potted windings on the axle and the hub shell, run at very high voltage from a battery powered controller tucked into the frame. The only trick would be making sure you get a decent electrical connection from the dropout to the hub. It wouldn't be geared, so the setup would be low speed/high torque rather than something like the Vivax which can run at high rpm. That kind of motor is much easier to make. And I have no clue if you could build this hub motor to actually look like a "normal" hub.

John Swanson

I think the way to approach this would be to embed electrical contacts in each dropout, with the locknuts and axle completing the circuit, put the coil (windings) on the axle, with ferrous inserts or magnets in the hub shell. You'd need to electrically insulate the rest of the drivetrain. Problem is, the hub on a pro road bike is skinny, and the axle has to be hollow and mechanically strong enough for a rider bombing down a mountain at 60 mph. That leaves very little room for a motor to produce enough power to make the whole thing worthwhile. If we start seeing pro bikes with bizarrely large diameter rear hubs, then someone should go put a magnetometer next to the hub shell - or toss a paperclip at it.

Here's a typical pro bike rear hub (a Zipp):

 

[jyl]

Re:

You can do more miracles with electricity than chemistry, it’s also less damaging to your health. -- Industry "guru" of moto-doping

The new frontier is far more technologically advanced and ten times as expensive. It’s in the rear wheel: it costs 200,000 Euros, and there’s a waiting list of six months. -- Gazzetta dello Sport

The above quotes are from the article cited earlier. The industry guru, whoever he is, seems pretty convinced. I imagine that if you don't care about your health, you can do even more miracles with the two in combination.

Meanwhile, notice that the Gazzetta dello Sport reporter isn't conjecturing about whether these electromagnetic wheels are possible; he's saying they're already in production, and that the backlog for them is six months. He's also saying that they have a price, two-hundred thousand euros each. That can only mean they are in production and being produced at a profit. And at that price they are not being bought for grand fondos.

These things are always impossible. Until they're not. From 2010 I recall reading some very good responses to the question of bottom bracket motors that drew upon seemingly solid knowledge of engineering and physics, and that said such motors were, if not impossible, impractical. Some of these arguments were so compelling that the debate was pretty much at a standstill - until little Femke Van den Driessche showed up, teary-eyed, with her motor bought with parakeet money.

I would suggest that Gazetta Dello Sport has printed quite a lot of fiction in its history. Italian sports media is not exactly Scientific American.

 

[GJB123]

Re:

You can do more miracles with electricity than chemistry, it’s also less damaging to your health. -- Industry "guru" of moto-doping

The new frontier is far more technologically advanced and ten times as expensive. It’s in the rear wheel: it costs 200,000 Euros, and there’s a waiting list of six months. -- Gazzetta dello Sport

The above quotes are from the article cited earlier. The industry guru, whoever he is, seems pretty convinced. I imagine that if you don't care about your health, you can do even more miracles with the two in combination.

Meanwhile, notice that the Gazzetta dello Sport reporter isn't conjecturing about whether these electromagnetic wheels are possible; he's saying they're already in production, and that the backlog for them is six months. He's also saying that they have a price, two-hundred thousand euros each. That can only mean they are in production and being produced at a profit. And at that price they are not being bought for grand fondos.

These things are always impossible. Until they're not. From 2010 I recall reading some very good responses to the question of bottom bracket motors that drew upon seemingly solid knowledge of engineering and physics, and that said such motors were, if not impossible, impractical. Some of these arguments were so compelling that the debate was pretty much at a standstill - until little Femke Van den Driessche showed up, teary-eyed, with her motor bought with parakeet money.

I think that almost nobody said it was impossible from a physics point of view. The discussion was more whether you could get it into the bracket of of a specific Specialized-bike used by Cancellara (as in that the bottom bracket was fully closed and needed to be opened for this which would not be conducive to the rigidity of said frame especially in race like RvV and PR). Moreover from Dutch TV it was quite clear that it was possible (the video has been linked to before).

 

[sniper]

Re: Re:

...
The 'rim drive' concept is a complete non-starter. When I read the report from Gazettta I had tears streaming down my face before the end. I have no idea what the guy's motivation is, probably just self publicity, but even if his system were to generate enough emf to turn the wheel the weight disadvantage at the rim would be huge (and remember the effect of inertia at the rim of a flywheel is proportional to the square of the radius).

yeah, i remember that

great post, @maxiton. my thoughts exactly.

These things are always impossible. Until they're not.

*like*

From 2010 I recall reading some very good responses to the question of bottom bracket motors that drew upon seemingly solid knowledge of engineering and physics, and that said such motors were, if not impossible, impractical. Some of these arguments were so compelling that the debate was pretty much at a standstill - until little Femke Van den Driessche showed up, teary-eyed, with her motor bought with parakeet money.

true story.