Belt Drives - the future?

On Fri, 1 Feb 2008 13:23:14 -0000, Nigel Cliffe wrote:

Peter Clinch wrote:
Mark T wrote:
www.bikebiz.com/news/29367/Carbon-belt-drives-are-standardised

Now that there's a new standard out there, does anything stand in
their way?

Initially, inertia from the innate conservatism of the bike market.
There will naturally be suspicion of a New! Improved! Thing replacing
something that, for all its faults, works pretty well and we're
familiar with it. Fixing something that doesn't seem to be borken,
in other words.

It will be a shame if belt drives just die through the conservatism of the
bike market. For a utility bike, a belt makes a lot of sense - no oil and
should last longer. I can see how it may work well off-road. I can't see
it ending up on race/audax machines (even though it is carbon fibre!),
except, possibly, in the recumbent arena.


Efficiency, beloved by racers and marketing droids, will be a big issue.
Bigger than it should be, probably; and murkier, certainly.

My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain. Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

Cleanliness is a possible advantage - but if you are going to have a hub
gear, you might as well have a chaincase; which would probably also remove
or reverse any durability advantage.

Howevere, this will be (sort of) "new", and manufactures love "new" - it
means that they can sell stuff to (some of) the installed base.

_ wrote:

Efficiency, beloved by racers and marketing droids, will be a big issue.
Bigger than it should be, probably; and murkier, certainly.

My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain.

But a lot of the point of this new one is it's meant to be just as
efficient as a chain.

Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

It is typical, but it's also changing. Hubs have come on a long way in
recent years while derailleurs haven't really changed /that/ much. if
they continue to improve (particularly the likes of the NuVinci CVT hub,
which just needs to get lighter AFAICT) this may start to be less of an
issue.

Cleanliness is a possible advantage - but if you are going to have a hub
gear, you might as well have a chaincase; which would probably also remove
or reverse any durability advantage.

I don't think so. An enclosed chain still needs lubrication, while a
drive belt doesn't.

It does have some clear advantages... as long as you don't particularly
need derailleurs for your particular application (and "need" can be
factored in as cost: they're popular at the low end in part because
they're not very sophisticated and thus cheap).

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

Peter Clinch Wrote:
_ wrote:

Efficiency, beloved by racers and marketing droids, will be a big
issue.
Bigger than it should be, probably; and murkier, certainly.

My recollection is that previous versions of belt drives were
estimated to
be less efficient that a well-lubricated new roller chain.

But a lot of the point of this new one is it's meant to be just as
efficient as a chain.

Belts do not
lend themselves well to derailleur gear systems, and that would add
the
typical lower efficiency of hub gearing.

It is typical, but it's also changing. Hubs have come on a long way
in
recent years while derailleurs haven't really changed /that/ much. if
they continue to improve (particularly the likes of the NuVinci CVT
hub,
which just needs to get lighter AFAICT) this may start to be less of
an
issue.

Cleanliness is a possible advantage - but if you are going to have a
hub
gear, you might as well have a chaincase; which would probably also
remove
or reverse any durability advantage.

I don't think so. An enclosed chain still needs lubrication, while a
drive belt doesn't.

It does have some clear advantages... as long as you don't
particularly
need derailleurs for your particular application (and "need" can be
factored in as cost: they're popular at the low end in part because
they're not very sophisticated and thus cheap).

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

The NuVinci is going to have to lighten up a lot before it is
seriously considered for most cycling applications. Here's one I built
into a Ryno Lite Wheel for a customer last week.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
YIKES!
Compare to a Rohloff in a downhill rim with a heavy downhill tire.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
It is my (so far totally unsupported) opinion that the NuVinci is
seriously over built, and a much lighter and more delicate version would
be adequate for the power output capability of most humans.
Dan


--
Dan Burkhart

On Sat, 2 Feb 2008 03:27:08 +1100, Dan Burkhart
may have said:

The NuVinci is going to have to lighten up a lot before it is
seriously considered for most cycling applications. Here's one I built
into a Ryno Lite Wheel for a customer last week.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
YIKES!
Compare to a Rohloff in a downhill rim with a heavy downhill tire.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
It is my (so far totally unsupported) opinion that the NuVinci is
seriously over built, and a much lighter and more delicate version would
be adequate for the power output capability of most humans.

I suspect that the NuVinci is probably not much, if any, overbuilt.
Gears handle low-speed/high-torque power transfer with ease, but
friction-based drive energy transfer systems need large contact
pressures, high traction levels, or large contact surface areas (or a
combination of these) in order to work without slipping. I suspect
that the NuVinci's makers discovered the limits of their concept in
the prototyping phase, and built the production model accordingly. To
make it a little lighter would probably increase the cost
substantially; to make it a lot lighter would probably put it into DoD
territory.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Werehatrack Wrote:
On Sat, 2 Feb 2008 03:27:08 +1100, Dan Burkhart
may have said:

The NuVinci is going to have to lighten up a lot before it is
seriously considered for most cycling applications. Here's one I
built
into a Ryno Lite Wheel for a customer last week.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
YIKES!
Compare to a Rohloff in a downhill rim with a heavy downhill tire.
http://tinypic.com/fullsize.php?pic=...&capwidth=true
http://tinypic.com/fullsize.php?pic=...&capwidth=true
It is my (so far totally unsupported) opinion that the NuVinci is
seriously over built, and a much lighter and more delicate version
would
be adequate for the power output capability of most humans.

I suspect that the NuVinci is probably not much, if any, overbuilt.
Gears handle low-speed/high-torque power transfer with ease, but
friction-based drive energy transfer systems need large contact
pressures, high traction levels, or large contact surface areas (or a
combination of these) in order to work without slipping. I suspect
that the NuVinci's makers discovered the limits of their concept in
the prototyping phase, and built the production model accordingly. To
make it a little lighter would probably increase the cost
substantially; to make it a lot lighter would probably put it into DoD
territory.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.
It would need a new name for the DoD. Something at least 3 words long
and acronym friendly. Oh wait, it already has that. Never mind.
Dan


--
Dan Burkhart

On Fri, 01 Feb 2008 19:49:45 GMT, still just me
wrote:

On Fri, 01 Feb 2008 13:49:45 GMT, _
wrote:


My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain. Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

How about stepping out of that box: belt drive with
expanding/contracting cylinders at the chainwheel and rear wheel? You
get infinite gearing within the range.

I'm sure Carl has picture of one from the 1880's.

Dear Bob,

Alas, belt drives for bicycles are more a modern notion.

In early bicycling, wet and muddy roads were commonplace, but modern
high-precision rubberized belts weren't available, so wrapping your
belt around two pulleys and hoping that your suspenders would keep
your pants up didn't occur to many inventors. They preferred rugged
inch-pitch chain, not sissified half-inch stuff.

Google the patents for bicycle and "belt drive" or "drive belt" and
you'll find that they first appeared when bicycles began turning into
motorcycles:
http://www.google.com/patents?q=bicy...e%22&scoring=2
http://www.google.com/patents?scorin...2drive+belt%22

Here's a typical early bike-pedal-chain on one side and
motorcycle-engine-belt on the other side:
http://www.nostalgic.net/pictures/1530.htm

The relative size of the rear sprockets reminds us that bicycles gear
up, while engine-powered vehicles gear down--even at low RPM, an
engine turns an order of magnitude faster than legs.

***

Chain, not belt, but expanding sprockets, front and rear:

http://www.google.com/patents?id=sQJ...663928#PPP1,M1

***

I'm not sure if the pulleys expand on this bike. In fact, I'm not sure
what they do:
http://www.google.com/patents?id=1rhoAAAAEBAJ&dq=519384

That inventor did better with cycling gun barrels:
http://www.google.com/patents?id=Sy1...=PA9&dq=502185

http://en.wikipedia.org/wiki/Richard_Jordan_Gatling

Cheers,

Carl Fogel

In article , still just me
says...
On Fri, 01 Feb 2008 13:49:45 GMT, _
wrote:


My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain. Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

How about stepping out of that box: belt drive with
expanding/contracting cylinders at the chainwheel and rear wheel? You
get infinite gearing within the range.

Vee belts are too inefficient compared to chains, although variomatic is
OK with cars where convenience can be more important than efficiency.
You could do it with a toothed belt - ISTR a chain-based system a while
ago where the effective diameter of the chainring was regulated by the
tension in the chain moving toothed sectors against springs.

On Fri, 01 Feb 2008 19:49:45 GMT, still just me
wrote:

On Fri, 01 Feb 2008 13:49:45 GMT, _
wrote:


My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain. Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

How about stepping out of that box: belt drive with
expanding/contracting cylinders at the chainwheel and rear wheel? You
get infinite gearing within the range.

I'm sure Carl has picture of one from the 1880's.
Dear Bob,

J.A. Little's design does have a belt drive:
http://www.google.com/patents?id=7qN...PA62&dq=605731

It uses four non-expanding pulleys, but it claims great efficiency,
possibly because there was no model to prove otherwise.

***

A toothed belt lurks somewhere inside Frederic P. Bemis's fantasy:
http://www.google.com/patents?id=qSU...=PP1&dq=617273

Again, it probably worked so well on paper that there was no incentive
to create a working model.

***

Luther H. Wattles (charming names are part of the old patents)
preferred the clean, simple toothed belt-drive:

http://www.google.com/patents?id=nkR...585416#PPP1,M1

Alas, I know of no actual belt-drive bicycles from that era, despite
the claims of soothingly noiseless propulsion. Perhaps someone
discovered that an oiled chain is rather quiet.

***

Albert Hansel had visions of pulleys and perpetual motion that
involved charging an impressive battery on descents and using the
stored power to charge up the next hill:
http://www.google.com/patents?id=bSt...=PP1&dq=656323

Like most such cranks, Albert got lost in irrelevant details, such as
declaring his preference that the pulley-wheels be made of aluminum,
and in even sillier fantasies, such as providing a lady's model when
he hadn't produced the men's model.

Again, no working model, probably because no rate of braking down the
hill to charge the monster battery would store enough power to get
back up to the top, since the power losses converting back and forth
are inescapable.

True, you could get a little feeble assistance if you were to put up
with going downhill very slowly, but somehow such self-charging
designs never enjoy much success outside the drawing-board and are
practically never seen where actual hills are found.

They always work better when freshly charged from an outlet.

Cheers,

Carl Fogel

aka Carl Fogel wrote:
...
The relative size of the rear sprockets reminds us that bicycles gear
up, while engine-powered vehicles gear down--even at low RPM, an
engine turns an order of magnitude faster than legs.
...
Mr. Fogel should be aware that large marine diesel engines operate in
very much the same RPM range as a hominid cyclist.

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

still just me wrote:

How about stepping out of that box: belt drive with
expanding/contracting cylinders at the chainwheel and rear wheel? You
get infinite gearing within the range.

Speaking as one who works with such drives in an industrial setting, such
devices on bicycles would be non-starters; they're hideously inefficient.

Tim
--
Sent from Birmingham, UK... all about me at www.nervouscyclist.org
'Now some people say that you shouldn't tempt fate, and for them I
cannot disagree - but I never learned nothing by playing it safe - I
say fate should not tempt me.' - Mary Chapin Carpenter