Chain drive versus belt drive efficiency

doozerie

The article is entitled Chain drive or belt drive - which is faster? but in reality the article really only touches upon that question. It may be of academic interest to some though.

…or of very real interest to those that take their commuter racing far too seriously

"The unexpected portion of the results becomes apparent when the efficiency of the belt itself is analyzed in an apples-to-apples tension comparison to the chain, without preload," Smith said. 'These results show the belt becomes more efficient above 208 watts."

tomasrojo

Are belt drives cleaner? That would be a selling point for a few people.

The chain drive, like the spoked wheel, has proven to be a very resilient design.

doozerie

Belt drives don't need lubrication so they should be cleaner. I've never one though so while the theory is sound I don't know whether it is really as simple as that in practice.

feck sake lads

looking at a belt drive trek in the quay cycles drogheda yesterday very nice indeed.a bike is only as fast as the rider.;)

Planet X

Limited to hub gears.

Planet X

Two years ago a guy did the Dying Light on a nice Rohloff / Belt Drive steed. Very slick indeed if a tad expensive.

Mycroft H

I'd love one. Something very cool about them.

Lumen

A fully enclosed chain connecting two sprockets is just about the most mechanically perfect device on earth. It is clean, quiet, light, reliable, easy to set up, tolerant of imperfection, cheap, and imposes no special design constraints on the rest of the bike.

Belt drives are, by contrast, almost none of these things.

Which is why almost nobody uses them.

fletch

Lumen wrote: »

A fully enclosed chain connecting two sprockets is just about the most mechanically perfect device on earth.

Maybe I am misunderstanding but most chains on ordinary aren't fully enclosed?

Lumen

fletch wrote: »

Maybe I am misunderstanding but most chains on ordinary aren't fully enclosed?

Fans of the belt drive point out that it's cleaner than a chain.

My point is that if you are prepared to tolerate a hub gear or single speed (which you have to be if you'd consider a belt drive), and you don't like the messiness of a chain, the obvious engineering solution is a chain case, not a belt drive.

nilhg

Lumen wrote: »

A fully enclosed chain connecting two sprockets is just about the most mechanically perfect device on earth. It is clean, quiet, light, reliable, easy to set up, tolerant of imperfection, cheap, and imposes no special design constraints on the rest of the bike.

Belt drives are, by contrast, almost none of these things.

Which is why almost nobody uses them.

That'll be why everyone here loves triples so.:D

I see someone patented a design for a bike transmission using continuously variable pulleys which if it could be produced in a light and compact enough system would be lovely on a bike especially with some sort of electronic control.

http://www.google.com/patents/US4119326

Combines used this system (still do) to set the speed of the parts of the threshing mechanism (and ground speed) that need to vary since the engine speed is usually constant, well proven.

Lumen

nilhg wrote: »

That'll be why everyone here loves triples so.:D

Damn. :pac:

nilhg wrote: »

I see someone patented a design for a bike transmission using continuously variable pulleys which if it could be produced in a light and compact enough system would be lovely on a bike especially with some sort of electronic control.

I think I'd rather see a design for a fully enclosed derailleur gear system.

Most city bikes don't need more than 3 gears. I would have thought with modern narrow chains that it ought to be possible to design a narrow cassette with a compact derailleur that could be fully enclosed.

BostonB

Kids bikes with enclosed chain are a PITA if the chain comes off.

Lumen

BostonB wrote: »

Kids bikes with enclosed chain are a PITA if the chain comes off.

That's true, but it's impossible for a properly tensioned chain to come off. Most kids bikes are thrown together by the manufacturer and then thrown around by the owner!

Wishbone Ash

Lumen wrote: »

....... Most kids bikes are thrown together by the manufacturer

..........or throw together by a parent on Christmas Eve using one of those tacky all in one spanners!

doozerie

Lumen wrote: »

Belt drives are, by contrast, almost none of these things.

But they have the edge when it comes to aesthetics. I mean, is this belt-driven yoke not a thing of beauty?...:

doozerie

I actually like the idea of a belt drive for my commuter, I must admit. That desire is fueled largely by laziness though, as the prospect of never having to degrease and re-lube a chain is very appealing. And the great thing about laziness being a motivator is that it also leaves me with no motivation whatsoever to consider any of the negatives. Yayyy!

BostonB

Certainly thrown together by a spanner anyway.

BostonB

doozerie wrote: »

But they have the edge when it comes to aesthetics. I mean, is this belt-driven yoke not a thing of beauty?...:

I dunno do you have a photo of it before it was run over and mangled?

Always curious about those A frame strider bikes. I think I've seen cleaner looking ones. I couldn't find an example. But found this.

http://beltbik.es/?page=1

http://www.id-performance.com/obj11/obj11.jpg

doozerie

@BostonB, I wasn't being serious about that A frame being lovely, the sight of them usually makes me flinch. In fact, I feel a little grubby just for having posted a picture of one.

Some good looking bikes in that first link that you posted above though. There do seem to be a variety of belt-driven bikes available these days, though the prices of some of them suggest that they are a niche product for people with deep pockets. I've not actually seen one on Irish roads but they have been available in some Irish bike shops as I knew someone that was considering one last year.

BostonB

LOL. I like the idea of the A frame but its just doesn't look great in practise.

I toyed around with getting a hub geared, or belt bike. But they are aways expensive, and if you have a problem, then parts and expertise in fixing them is an issue. Whereas everyone knows chains and Shimano.

Found this also...

http://forum.dahon.com/index.php?showtopic=8607

enas

Lumen wrote: »

the obvious engineering solution is a chain case, not a belt drive.

You're absolutely right here. They're an equivalent solution to the same problem, but a cheaper and simpler one, so that's better engineering. That's why fully enclosed drivetrains, with hub gears, are so ubiquitous on Dutch utility bikes. On the other hand, there's no contest on the aesthetic aspect: the belt drive wins hands downs, in terms of offering a pure and slick aspect. It's very hard to beat the beauty of that for example (don't be put off by the whiteness of the bike, the photo really doesn't do it justice). This frame is also nice in that it has a removable dropout in order to remove the belt, instead of a cut in the frame as most other belt drive frames.

Lumen

enas wrote: »

On the other hand, there's no contest on the aesthetic aspect: the belt drive wins hands downs, in terms of offering a pure and slick aspect. It's very hard to beat the beauty of that for example (don't be put off by the whiteness of the bike, the photo really doesn't do it justice).

It's a horribly ugly bike. The tubes are all funny profiles, the seatpost junction is a total mess, and the stem is far too short.

More importantly, it has no eyelets or clearance for mudguards. What's the sense in buying a belt drive to keep oil off your trousers if you can't fit mudguards and so get covered in road muck instead?

Would not bang.

enas

Lumen wrote: »

[...]What's the sense in buying a belt drive [...]

Buying a bike like that makes simply no sense. It makes much more sense as a bike to see at a show or exhibition (and again, the photos doesn't give it much justice). Of course, the aesthetics appeals more to singlespeed/fixie fans (of which I'm not particularly, incidentally).

And the integrated seatpost clamp is actually very nice too!