Belt Drives - the future?



[email protected] wrote:

>> 2) Could the belt ever slip?
> It looks like a toothed belt to me so no, it will never slip. (Much as
> the cambelt on a car never slips - at least, if it does you've got a
> very expensive problem to sort out)

Toothing doesn't necessarily stop something slipping. Even a convential
bike chain can slip (skip) if it's not quite matched to the sprockets.

~PB
 
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?

Interested to see Gates are involved. Several of their senior management are
in the Dumfries Cycle Club.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Drivers in the UK kill more people every single year than
;; Al Qaeda have ever killed worldwide in any single year.
 
In article <[email protected]>, _
[email protected] says...
> On Fri, 1 Feb 2008 13:42:17 -0000, Dave Larrington wrote:
>
> > In news:[email protected],
> > Mark T <pleasegivegenerously@warmail*turn_up_the_heat_to_reply*.com.invalid>
> > tweaked the Babbage-Engine to tell us:
> >> <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?
> >
> > o Can't be retrofitted to an existing bike (or can it?)
>
> Oooo, yes.
>
> That'd have to be a design challenge; either a separable belt, a detachable
> chainstay, or a frame made to be disposable if the belt should fail.
>
Proper old-fashioned bikes with full chain cases have removable seat
stays.
 
Dave Larrington wrote:

> In news:[email protected],
> Mark T
> <pleasegivegenerously@warmail*turn_up_the_heat_to_reply*.com.invalid>
> tweaked the Babbage-Engine to tell us:
>> <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?
>
> o Can't be retrofitted to an existing bike (or can it?)

Probably not, because you need to be able to open up the rear triangle to
fit it. So there needs to be some sort of openable joint, probably between
the seat stay and the dropout.

> o hub gears only so gear range is of necessity limited even if one can
> afford a Rohloff

A Rohloff has as wide a range of gears as a typical 27 speed mountain bike
setup. You want more than that?

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; IE 3 is dead, but Netscape 4 still shambles about the earth,
;; wreaking a horrific vengeance upon the living
;; anonymous
 
In article <[email protected]>, Simon Brooke
[email protected] says...
> Pete Biggs 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?
> >
> > Some questions that come to mind:
> >
> > 1) Has it been independently tested to see if efficiency really is as
> > high
> > as with a conventional chain - and at high torque? Or do we just have the
> > designer's word for it?
>
> The torque involved is nothing compared to the torque which these belts
> transmit in other applications, so that isn't an issue. What is an issue,
> as far as I'm concerned, is efficiency - I'm /highly/ sceptical as to
> whether these things can be made as efficient as chain drive.
>
> Note that this isn't ever going to work with a derailleur; it's going to be
> used with epicyclics, single speeds or fixies. Note also that the people
> involved in the project are Nicolai (mainly interested in downhill bikes)
> Orange (interested in mountain bikes generally but with a substantial
> interest in downhill), and the technology specialist companies. I suspect
> that transmission efficiency isn't that good.
>
> > 2) Could the belt ever slip?
>
> It's toothed. And it's the same technology that's used for motor engine cam
> chain belts, which must never slip or you get very expensive damage to the
> engine.
>
> > 3) How critical is belt tension? Will the usual methods of tensioning be
> > adequate?
>
> About the same as for chains.
>
> > 4) How long will it last? Will it wear out from friction?
>
> In car engine applications, typically 50,000 miles at average about 3,500
> rpm, or something like 262 million rotations of the whole chain. Or, put it
> differently, the lifetime of several bicycles. Belts outlast chains in
> camshaft applications by a factor of about two - and those are chains which
> are running in an oil-bath, which ours aren't.
>
> > 5) What kind of sprockets will be needed, and what chainsets and hubs
> > will they fit?
>
> None. You'll have to have new ones, purpose made.
>
I don't see why you couldn't bolt a toothed pulley to a regular
chainset, or slide one onto a cassette hub.
 
On Fri, 01 Feb 2008 13:49:45 GMT, _
<[email protected]> 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.
 
Simon Brooke wrote:

>> 2) Could the belt ever slip?
>
> It's toothed. And it's the same technology that's used for motor
> engine cam chain belts, which must never slip or you get very
> expensive damage to the engine.

The speeds are low but the amount of torque applied by a cyclist is high.
Some figures on how it compares to that involved in cam belts might be
interesting.

I noticed that it's a toothed belt, but I can imagine one skipping if there
was a little bit too much mismatch or flexibility.

~PB
 
On Fri, 01 Feb 2008 19:49:45 GMT, still just me
<[email protected]> wrote:

>On Fri, 01 Feb 2008 13:49:45 GMT, _
><[email protected]> 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=bicycle+"belt+drive"&scoring=2
http://www.google.com/patents?scoring=2&q=bicycle+"drive+belt"

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=sQJqAAAAEBAJ&printsec=abstract&zoom=4&dq=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=Sy1EAAAAEBAJ&pg=PA9&dq=502185

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

Cheers,

Carl Fogel
 
In article <[email protected]>, still just me
[email protected] says...
> On Fri, 01 Feb 2008 13:49:45 GMT, _
> <[email protected]> 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
<[email protected]> wrote:

>On Fri, 01 Feb 2008 13:49:45 GMT, _
><[email protected]> 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=7qNYAAAAEBAJ&pg=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=qSUrAAAAEBAJ&pg=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=nkRgAAAAEBAJ&pg=PP1&dq=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=bStYAAAAEBAJ&pg=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
 
[email protected] 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
 
Simon Brooke wrote:
>> 2) Could the belt ever slip?
>
> It's toothed. And it's the same technology that's used for motor engine cam
> chain belts, which must never slip or you get very expensive damage to the
> engine.
>
do you propose to make a bikeframe as stiff as an engineblock?

>> 3) How critical is belt tension? Will the usual methods of tensioning be
>> adequate?
>
> About the same as for chains.
>
reading the specs, it has to be much more precise


>> 4) How long will it last? Will it wear out from friction?
>
> In car engine applications, typically 50,000 miles at average about 3,500
> rpm, or something like 262 million rotations of the whole chain. Or, put it
> differently, the lifetime of several bicycles. Belts outlast chains in
> camshaft applications by a factor of about two - and those are chains which
> are running in an oil-bath, which ours aren't.

Where did you dig this up? Camshaft chains last the lifetime of the
engine, belts you replace on a rigorous schedule

>
>> 6) How much will the chain and sprockets cost?
>
> There's no reason for it to be more expensive, except novelty -

And the things being 10 times as wide, making them impossible to stamp
with any precision doesn't count?


I'd expect
> it to be less expensive. Car camshaft belts - which is essentially what
> these are - are not expensive.

Don't expect a chinese knock-off for 2 ukp soon!


--
/Marten

info(apestaartje)m-gineering(punt)nl
 
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
 
In article <[email protected]>, Peter Clinch wrote:
>
>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.

The overall range of the NuVinci is less than a Rohloff, or than
at least some derailleur systems. It's more than adequate for many
uses though.
 
In article <[email protected]>, M-gineering
[email protected] says...

> And the things being 10 times as wide, making them impossible to stamp
> with any precision doesn't count?
>
They'd be diecast, but you know that so why suggest stamping?
>
> I'd expect
> > it to be less expensive. Car camshaft belts - which is essentially what
> > these are - are not expensive.
>
> Don't expect a chinese knock-off for 2 ukp soon!
>
Could be amusing. :)
 
In article <[email protected]>, Dave Larrington wrote:
>In news:[email protected],
>Mark T <pleasegivegenerously@warmail*turn_up_the_heat_to_reply*.com.invalid>
>tweaked the Babbage-Engine to tell us:
>> <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?
>
>o Can't be retrofitted to an existing bike (or can it?)

On most bikes, not short of brazing/welding/whatever a new belt-specific
splitable rear triangle on the drive side.


>o hub gears only so gear range is of necessity limited even if one can
>afford a Rohloff

If one can afford both a Rohloff and a Schlumpf one could extend that
range to something fairly enormous though. That's a big if though.
But cheaper hub gears are plenty for many people.
 
On Sat, 02 Feb 2008 06:05:14 +0100, M-gineering
<[email protected]> wrote:

[---]

>Camshaft chains last the lifetime of the
>engine, belts you replace on a rigorous schedule

That's true - as they get older, timing chains just get noisy. They
are not nearly so subject to catastrophic failure as belts.
 
On 2008-02-02, Andrew Price <[email protected]> wrote:
> On Sat, 02 Feb 2008 06:05:14 +0100, M-gineering
><[email protected]> wrote:
>
> [---]
>
>>Camshaft chains last the lifetime of the
>>engine, belts you replace on a rigorous schedule
>
> That's true - as they get older, timing chains just get noisy. They
> are not nearly so subject to catastrophic failure as belts.

It's true that timing chains last longer than timing belts.

But a timing chain is fully enclosed, perfectly clean, and gets sprayed
with oil constantly.

A drive belt on a bicycle made out of similar stuff to car timing belts
should last much longer than a normal non-enclosed bicycle chain.

Even the alternator belt on a car lasts for several years and tens or
even hundreds of thousands of miles and transfers around 10 times as
much power as a bicycle chain.
 
In article <[email protected]>,
Tom Sherman <[email protected]> wrote:

> [email protected] 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.

What? Each cylinder fires 1 to 1.5 Hz?

--
Michael Press
 
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