|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
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. |
Ads |
#2
|
|||
|
|||
Belt Drives - the future?
_ 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/ |
#3
|
|||
|
|||
Belt Drives - the future?
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 |
#4
|
|||
|
|||
Belt Drives - the future?
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. |
#5
|
|||
|
|||
Belt Drives - the future?
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 |
#6
|
|||
|
|||
Belt Drives - the future?
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 |
#7
|
|||
|
|||
Belt Drives - the future?
|
#8
|
|||
|
|||
Belt Drives - the future?
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 |
#9
|
|||
|
|||
Belt Drives - the future?
|
#10
|
|||
|
|||
Belt Drives - the future?
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 |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Belt Drives - the future? | Mark T[_2_] | UK | 47 | February 4th 08 11:25 AM |
Saw-tooth drives | [email protected] | Techniques | 2 | January 30th 08 07:37 PM |
Motorist drives along pavement | David Hansen | UK | 96 | April 6th 06 06:45 PM |
Belt Drives | Tosspot | UK | 12 | August 13th 05 08:41 AM |
StupidTales: new shoes and blood drives | BraveSirStupid | Unicycling | 7 | February 23rd 05 04:14 PM |