
Ceramic-bearing bicycle drive shaft (2018) - tomcam
https://www.bikeradar.com/news/faster-than-any-chain-ceramicspeed-driven/?image=3&type=gallery&gallery=1&embedded_slideshow=1
======
ben7799
Not sure why this is coming up again a year later.

They put it out as a marketing thing. It had a bunch of impractical caveats.

They haven't announced they solved any of the problems with it in the year
since they put it out.

The friction thing & drivetrain is mostly a non-issue. If you're riding fast
enough to care the % drag from the chain/drivetrain gets smaller and smaller
the faster you go. It's pretty much a non-factor compared to air resistance.

You get way more benefit from doing some extra stretching and yoga so you can
lower your handlebars and still ride hard than you do changing to ceramic
bearings or fiddling with expensive lubricants or chains/belts/shaft drives.

~~~
hadlock
Agreed, rolling resistance at 30mph (about the fastest you'll ever ride a
bike, even down a steep hill) is about 50w of energy, whereas wind resistance
at that speed is close to 1000w of energy.

Compare to 10mph (average speed for most casuals) where your total wind +
drivetrain is about 50w of energy. Wind resistance goes up by the cube,
drivetrain is mostly linear.

~~~
u801e
> Agreed, rolling resistance at 30mph (about the fastest you'll ever ride a
> bike, even down a steep hill)

What do you consider a steep hill? There are hills here that I can routinely
get up to 35 mph with a little effort. Many cyclists have gone downhill at
speeds exceeding 50 mph [1].

[1]
[https://www.youtube.com/watch?v=sc2nqMXlZWg](https://www.youtube.com/watch?v=sc2nqMXlZWg)

~~~
CamperBob2
Most people who aren't hardcore cyclists with really nice bikes are going to
chicken out around 30 MPH.

Or they should. 30 MPH is _fast_ on a bike. If anything goes wrong, it's going
to hurt.

~~~
LargoLasskhyfv
Then i've been lucky, since i did that and much more in the past. Nowadays i'm
doing 22 to 23 up to 28 peak on flat ground with no headwind. On a decades old
3-speed, with coaster/back pedal brake, mud guards and basket on the
(rear)carrier. (27x1 1/4 pumped to 7.5 to 8 bars)

The only thing of going wrong i can think of is insects in the eye, and
generally unpleasant airstream in the eyes. Use sports glasses. Problem
solved. Anything else is situtational awareness, maybe a helmet, and good
maintenance.

------
parsimo2010
A little background on this and a thought:

Friction Facts started out as a guy (with an engineering degree) that
developed his own test equipment to measure drivetrain losses under load. He
eventually published his own wax formulation so that a DIYer could replicate
his best effort at reducing chain friction. It produced a chain that had about
4 watts of loss, which is pretty good. That's over 98% efficient for a person
putting out 250 watts. 250 watts is high for someone that's never ridden a
bike, doable for someone that commutes by bike every day, and a pro wouldn't
even break a sweat. So going to 99% improvement, or "reducing friction by 49%"
sounds like a lot, but you're only gaining back 2 watts out of 250. Also,
Friction Facts felt really cool when is was just a backyard engineer
publishing his results, but then he got bought and took all his
results/website offline. Luckily the internet archive and many forum posts
have the major results, but it felt kind of like he was selling out to the
man. I understand that he has bills to pay so I'm not mad at him. I also
understand that a regularly lubed bike chain has higher than 4 watts of loss
and most people aren't willing to melt wax on their stove to wax their own
chains (I do though).

The CeramicSpeed concept couldn't shift in 2018 and they haven't demoed a
shifting version as of August 2019. The pie plate at the back is only for
looks, and claiming 13-speeds is totally worthless at this point. Heck, I
could CNC a 30-speed cog for the back, since it would fit inside the diameter
of the wheel. I predict that when a shifting system is functional, it will
increase the complexity and add to the friction of the drivetrain, bringing to
about the same level of friction as top end chain based systems from Shimano,
SRAM, and Campagnolo.

This is a promising idea, but ultimately it's _worth more as a way to avoid
patent infringement_ than it is to make a faster bike. Another smaller player,
Rotor, makes a 13-speed system that shifts hydraulically. Rotor's marketing
claims that hydraulics shift better, but everyone knows that it's just a way
to keep from stepping on the established players' toes.

~~~
LeifCarrotson
In round numbers, the drivetrain causes about 4 watts of loss.

Tire rolling resistance costs about 40 watts (on regular roads with road bike
tires; less in a velodrome and more with knobby, thick mountain bike tires).

The bike itself costs 8 ~60 watts or so in air resistance, less for aero,
deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more
importantly, air resistance increases with the square of velocity, no matter
your starting drag coefficient.

The remaining 150 watts or so are caused by rider air resistance.

And of course, all 250 watts are produced by the rider and dependent on their
fitness level.

Clearly, the best way to go faster is to put more energy in. Next, improve
your posture to produce less drag. However, it's easier to spend money than to
sweat and suffer, so people instead turn to aero bikes, tires, and the
drivetrain.

~~~
track_me_now
>> However, it's easier to spend money than to sweat and suffer

not disagreeing with anything you're saying, however at the super-elite level
_everyone_ puts in the maximum amount of perfectly allocated effort into
training and preparation. _if_ we could eliminate 4 watts of drive train
friction loss that would be material. For your average weekend warrior the
points you make are definitely true, but hey, not the worst thing to blow your
money on...

------
makomk
Previous HN discussion:
[https://news.ycombinator.com/item?id=17494226](https://news.ycombinator.com/item?id=17494226)

Can't imagine this catching on. Ordinary chains are already really efficient,
and the efficiency of this will only last until dirt gets into all those tiny
little open bearings. (Sealed bearings would eat into the efficiency gains.)

~~~
jacobush
Something which would be cool would be a electric hybrid drive. Electric
generator + electric motor.

~~~
nradov
You can already buy electric bicycles. But regenerative braking on such a
light vehicle doesn't gain enough to be worth the extra weight.

~~~
braythwayt
I know someone who uses an electric cargo bike. It has regenerative braking,
and perhaps the extra mass of carrying loads is what makes it practical.

I believe it uses the Bionx system, which uses a direct hub drive. The company
is lo longer in business, IIRC.

------
wlkr
I think the biggest innovation of this kind that I've seen in use (anecdata,
of course) is the number of commuter bikes fitted with belt drivetrains (Gates
Carbon Drive) paired with internally geared hubs. The reduction in maintenance
effort is purported to be significant and it's not only limited to high-end
bikes (plus it can be retrofitted although non-trivially for the majority of
frames). When the cog wear becomes too bad on my single-speed I'll look into
fitting a belt drive, if possible.

~~~
vinni2
I have been using a bike with belt drive for about 2 years and while the lack
of chain reduces some maintenance doing other maintenance like switching tires
gets more complicated.

And of course the loss of efficiency due to belt drive is also pretty bad.

I am convinced that this will be my last belt drive bike.

~~~
pkulak
If you're a tinkerer, and you like swapping tires, doing all your own
maintenance, etc, then I agree with you 100%.

However, my bike is my car. I'd no sooner swap out my own bike tire than I'd
swap out my own car tire. Not that I can't, it's just not something I enjoy
doing. My hub-geared, belt drive, hydraulic-disc bike is incredibly difficult
to maintain... but I also just bring it in to my local bike shop once per
winter. That one trip is all the maintenance it needs for the 3200 miles I put
on it per year, mostly in the rain. I'd never go back to lubing a chain every
week, putting new pads on every month, replacing the chain every 3, etc. 6
months after I bought this bike I gave away my repair stand and it was
glorious.

~~~
sbierwagen
>I'd no sooner swap out my own bike tire than I'd swap out my own car tire.

In my neighborhood I get a flat every other month. If I had to pay someone
else to replace inner tubes it'd cost as much as driving a car.

~~~
pkulak
What tires do you run? That'll happen to me unless I run touring tires. With
Schwalbe Marathons front and back, I never get flats.

~~~
entee
There are also very tough plastic liners you can put between the tire and the
inner tube. At some point picked up a 1 cm cut in the the tire that this inner
layer not only prevented a puncture but kept the whole tire/tube/wheel
together until I noticed it by happenstance weeks later. Search for Mr. Tuffy
liner but there are others.

~~~
LargoLasskhyfv
Tried them, felt bad, was harder to drive. The same goes for stuff like
Schwalbe Marathon. When i look back into the times where i bicycled more, i
wonder how i managed with the tires which had just a thin mesh of wires
embedded? I feel like the modern stuff has more planned obsolescence built in.
Tubeless makes no sense economically to me, so i go with a small can of
breakdown spray.

------
snak
I'm an enduro and downhill rider myself, and I don't see these coming anytime
soon to the "mountain bike" world. Looks fragile and susceptible of failure
under high forces and dirt/mud.

~~~
salty_biscuits
I am waiting for gearboxes to become competitive with derailleurs. Would
totally be up for getting rid of that fragile and expensive part.

~~~
romwell
>I am waiting for gearboxes to become competitive with derailleurs

You mean the internal gear hubs?

They've been competitive for over a hundred years[1].

I had a bike with an 8-speed SRAM[2], it worked fine (got stolen one day).

[1][https://www.sheldonbrown.com/internal-
gears.html](https://www.sheldonbrown.com/internal-gears.html)

[2][https://www.sheldonbrown.com/sram-g8.html](https://www.sheldonbrown.com/sram-g8.html)

~~~
salty_biscuits
Not in the hub, bad for unsprung mass. In the bottom bracket like this

[https://pinion.eu/en/](https://pinion.eu/en/)

But has some tradeoffs that mean it isn't quite there yet.

------
asteli
What are the efficiency numbers when using normal, grease and shield laden
bearings? This might have a place in cycle sprints or other short distance
disciplines where you have a lot of time for prep, but the benefits are quite
moot if you have to swap or service bearings every hundred km.

~~~
avip
92-96%

~~~
logicallee
are those actual numbers or are you just showing it is high?

I'd have guessed it's more like 99%. isn't anything that isn't heat or noise =
perfect efficiency? a normal bike chain doesn't get hot or make much noise at
all, does it? seems to me just about 100% efficient. maybe transfers a bit of
vibration to the rest of the frame? but not 8%-4% of its transferred force....

~~~
jdietrich
This paper gives a very detailed analysis of chain drive efficiency:

[http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf](http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf)

~~~
logicallee
Wow, thanks. I only had a quick look but Figure 2 seems to show 91.5%-95%
efficiency depending on configuration. Very detailed study and it sounds like
it would answer all my questions if I spent an hour reading it.

------
londons_explore
The sideways forces on those sprockets are going to lead to very rapid
failure...

~~~
laputan_machine
Absolutely, putting full-load on those sprockets is not going to happen,
either the sprockets will bend or the bearings will pop-out. Interesting
design tho

------
Theodores
The detail about changing gears is glossed over, there is that big stack of
what look like sprockets so it is assumed that changing gear is possible, but,
get to the bottom of the article, and it isn't.

This is doing well as a fake-halo product for Ceramic Speed and their existing
products, it is a crowded marketplace and not many people care about bike
bearings, this product makes people aware that there is room for efficiency
gains.

~~~
cr0sh
> The detail about changing gears is glossed over, there is that big stack of
> what look like sprockets so it is assumed that changing gear is possible,
> but, get to the bottom of the article, and it isn't.

Actually, it's not - take a look at the renderings again.

If you notice (and the article details) the rear "cassette" is actually a flat
disk with concentric "gearing" which the roller bearing "gear" on the shaft
interfaces with.

Switching gears would be accomplished (in theory) by moving the roller bearing
"gear" in and out along the radius of the rear disc "gear".

It reminds me in a way of old wood "peg" and "lantern" gearing seen in
wind/water mills and similar old power transmission systems, except in this
case the "peg" gear is a formed or cast disc, and the "lantern" (which you
couldn't shift due to the plates at the ends) is a "ring" of bearings, the
bearings forming the "teeth" of the gear (which isn't that strange, if you
understand how a simple gear is basically formed out of partial circles along
the edge of a larger circle, all "joined up").

They do mention though, at the end of the article, that they can't shift gears
easily and something about an internal wireless servo (which I think is kinda
daft). I would instead use a splined shaft, and just change the "length" of
the shaft to move the end-gear in/out of the wheel gear, and actuate it with a
normal lever and bowden-cable type arrangement, though that might interfere
with their efforts/want for more efficiency...

~~~
Theodores
The thing is that this gadget has been doing the rounds of trade shows for
more than a year with this unfinished detail of having it actually change
gear.

There is this difference between theory and practice. So even if there was a
solution - yours is elegant b.t.w. - then it would take a whole lot of testing
and fine tuning to get right.

I am actually quite astonished at how bicycle parts evolve, the derailleur
took the best part of a century to get indexed gears and those took decades to
go from clunky to smooth. What took so long to get right? Scores of
refinements were needed, e.g. to the sprocket teeth profiles, to being able to
manufacture a decent chain to basics of friction in cables. Then there is the
challenge of mass manufacturing these things so they are durable and precise.

I am not dismissing the ceramic speed shaft innovation - it gets people
thinking - but I doubt my bike will be losing its chain any time soon!

------
deaps
I think one of the biggest problems is as the rear cassette shifts toward a
larger gear, flex could become an issue. The driveshaft will push out on those
larger gears making the 'disc' flex toward the wheel. Those larger gears are
where you'd be when climbing a hill - where you're typically putting out a
good bit of power too.

It's a great idea, and I do love innovation. I've honestly never really had a
problem with a chain though, myself.

I have about 6,000 miles on my cross bike (that gets used in some pretty
dirty, dusty, sometimes-muddy conditions). And maybe 2400 on my newer road
bike. I just clean the chain with wd-40 when it's dirty (sometimes water/soap
first if really muddy), dry it well with a rag, then apply some liquid chain
lubricant (sometimes after every ride, if it's needed).

~~~
samstave
I have more miles than you :-) (14,000) ((I have exclusively biked for over a
decade))

But you know what might be an interesting design idea:

Make a shaft drive like this which is centrally aligned. But the bike has TWO
rear wheels as closely spaced as possible and the shaft drives a single axle
for the rear -- but has more gearing up front...

But make the two rear wheels with a camber such that they angle out slightly
such that their centerlines are as clos as possible - allowing for turning to
be essentially the same as a single-rear-wheel bike...

~~~
cr0sh
I'm curious as to how you would drive both rear wheels with a single central
shaft? Both sides would rotate in opposite directions; I can't find a good
example to illustrate what I am saying, unfortunately. I trust you understand
what I mean.

Now - there might be a way around this, but it would probably introduce more
complications and friction to the mix (one way would be to drop/raise the
central shaft off-center of the driving wheels centerline, then have separate
fore/aft gearing on the shaft to drive the wheels in the proper direction).

~~~
samstave
Shoot I think you may be correct. I hadnt thought of that aspect. Maybe it
would require the central shaft to rotate a single gear in the forward
direction which was attached to via smaller chain that rotates the axle
between the two wheels...?

Yeah... basically what you said in the second paragraph of your comment....

This would be a fun design challenge. Anyone Solid on Solid Works want to give
it a go???

\---

OH . I thin I have it, but I dont know how efficient it would be:

A Worm Gear:

[https://i.imgur.com/BgJODdP.jpg](https://i.imgur.com/BgJODdP.jpg)

~~~
robotresearcher
Here's a solidworks tutorial making a differential gear which is how many/most
vehicles solve this problem.

[https://youtu.be/qqFTMhubEtc](https://youtu.be/qqFTMhubEtc)

A differential gear solves both the direction problem and the distance between
the wheels when turning problem.

------
buro9
Having been dumb enough to use ceramic bearings in a BMX bottom bracket, and
in the hubs of a mountain bike... I would not purchase this system.

The replacement rate for those bearings would be astonishing.

~~~
olyjohn
Care to expand this comment? Do ceramic bearings have a higher wear-rate than
a traditional steel ball bearing?

~~~
speakeron
Hambini has a good article on this[1]. The basic problem (apart from cost) is
that only the ball bearing itself is ceramic; the inner and outer races are
made of steel and the ball wears a groove into them which increases friction
over time. Near the bottom of the article there's a 'power consumption vs
kilometres' chart which illustrates this nicely.

 _" Hybrid ceramic bearings are the equivalent of trying to run a locomotive
on an asphalt road - the hardness differential causes the road (raceway) to
become damaged."_

[1] [https://www.hambini.com/blog/post/ceramic-bearings-vs-
steel-...](https://www.hambini.com/blog/post/ceramic-bearings-vs-steel-
bearings...-an-engineering-opinion/)

------
kazinator
"The first shaft drives for cycles appear to have been invented independently
in 1890 in the United States and Britain."
([https://en.wikipedia.org/wiki/Shaft-
driven_bicycle](https://en.wikipedia.org/wiki/Shaft-driven_bicycle))

This basic idea has had over a hundred years to take off.

The particular design seen here appears particularly impractical.

The rear shifting mechanism has a poor selection of gear ratios for road use.
The gear ratios are not sufficiently close. In my bike I have a Shimano Claris
(or Sora?) cassette like this: with 12-13-14-15-17-19-21-23 teeth:

[https://i.imgur.com/BFFBYzj.jpg](https://i.imgur.com/BFFBYzj.jpg)

Even if the drive train has a bit more efficiency, if the gear ratios are bad,
that will be a deal breaker, because bad gear ratios wreck the efficiency of
the human power plant.

The system has to be extremely rigid for the gears not to skip. If there is
any flexibility in the system, it requires massive preload to hold the parts
in contact. The chain solves this problem; its own tension binds it to the
sprocket teeth.

The rear engagement mechanism has a kind of gear made up of a dozen tiny
bearings. Once dirt from road spray gets inside those, they are done.

This is a basically a fair weather toy for yuppies who don't know anything
about bicycles.

------
vr46
I’ve had two shaft drive motorbikes now and appreciated the low maintenance
and general cleanliness but they are heavier than chain drives. On a bicycle,
this looks great, although it would be better off enclosed for protection -
but fewer showhorse points.

------
tcmb
There's a very in-depth talk by Keith Wakeham, arguing that shifting is
practically impossible with this system:
[https://www.youtube.com/watch?v=o9d_cBGXMwY](https://www.youtube.com/watch?v=o9d_cBGXMwY)

If I understand it correctly, the issue is that the driveshaft has to move
from one "sprocket" to the next in a very small amount of time at high
rotational speeds of the cassette. Because of the weight of the bearings at
the end of the driveshaft, a very large force is required to accelarate it.

------
tlb
Here's a picture I took of the 1899 version, in the fascinating bicycle museum
in Amsterdam: [https://imgur.com/ZnA4kEM](https://imgur.com/ZnA4kEM)

------
the-dude
What is the news here? In NL cardan-bicycle's are commercially available.

~~~
Jackim
This design doesn't use bevel gears.

------
victorbojica
What I'm curious about is, how robust is it? How does it handle bumpy rides
and rough terrain? The article doesn't say anything about it and i can't tell

~~~
bdamm
Nor can anyone, because it doesn't actually exist as a product that can be
tested. This pops up every few months for some reason, with the same note: The
rear shifter is not controllable. A wire to the back half with a bearing to a
ring around the drive shaft would solve that, but I'm guessing that messes
with their stated high efficiency goal.

------
Empact
Was a fan of Dynamic Bicycle's earlier (now discontinued) version of this, but
not to the point of ever riding or buying one. They used an internal hub gear
for shifting:
[http://web.archive.org/web/20160124015048/http://shop.dynami...](http://web.archive.org/web/20160124015048/http://shop.dynamicbicycles.com/Runabout-8-18-Frame-
Size-Runabout8S-18.htm)

------
Animats
Right, this is about going from 98% to 99%, which is not all that useful.
Bearings today are quite good.

Before ball and roller bearings, though, it was really bad.[1]

[1]
[https://www.youtube.com/watch?v=Peu5hH9vy7E](https://www.youtube.com/watch?v=Peu5hH9vy7E)

------
rasz
1% drivetrain efficiency using fancy expensive fragile materials ... or $100
300W hub motor for effortless commute? choices choices

------
rienbdj
iirc a single speed or fixed gear setup is already as efficient and the
prototype can't change gear anyway...

------
iicc
(2018)

~~~
2T1Qka0rEiPr
Thanks for actually pointing this out, when I read the article I thought I'd
seen the exact same concept bike in a Global Cycling Network (GCN) video last
year. Makes sense.

------
avip
Not unrelated to the patent
[https://patents.google.com/patent/EP0105949A3/ko](https://patents.google.com/patent/EP0105949A3/ko)

~~~
NietTim
2019-08-16 Application status is Expired

What a funny coincidence

(Not implying anything about the company in article, the article is from july
2018)

~~~
mattkrause
I, too, thought I had magic patent expiring powers, but that line shows
today’s date and the status as of today.

If you check tomorrow, it’ll say “2019-08-17 Application status is Expired”
instead.

~~~
NietTim
Of course, this makes so much sense, and it changed indeed, hahaha

------
johnr2
> Ceramic-bearing drive shaft is twice as efficient as Dura-Ace, company
> claims

A conventional chain in good condition is >90% efficient. How do you double
that?

~~~
tln
Maybe they should have said "half the inefficiency"

------
ptah
a video or animation would be helpful

~~~
srrr
[https://www.youtube.com/watch?v=UFAQ6CzNm7s](https://www.youtube.com/watch?v=UFAQ6CzNm7s)

------
Grustaf
My God that’s an ugly crank!

------
betimsl
It's never going to work.

------
samstave
As a 100% bike commuter for the last decade.....

I need one of these YESTERDAY.

How get.

Ill trial the fuck out of this thing.

~~~
rasz
you need this 1% efficiency boost? one percent

