I've never ridden a recumbent, but I am intrigued.

However, looking at the available recumbent bikes I'm struck by the length of the chain. Good grief, that looks like a multitude of problems just waiting to happen.

I'm also not a fan of derailleurs. Yes, I know, they've been around longer than I have, and are proven mechanically sound. Whatever. Don't like 'em.

I've been looking at the chainless bikes manufactured (distributed?) by Dynamic (http://www.dynamicbicycles.com/), and looking at the RANS Rocket. And I thought to myself, why not just use a longer drive shaft and an internally geared hub. Less maintenance, no greasy chains flopping around, cleaner lines. What's not to like?

I'm not a mechanical engineer, but I think it's a simpler solution than what Kretschmer has suggested. (http://www.bhpc.org.uk/HParchive/PDF/hp49-1999.pdf page 11)

What do you think?

By all means, rig one up and let us know how it goes! :)

...What's not to like?..

What do you think?

- heavier
- more friction
- non-standard parts

I have ridden a production shaft drive bike [Biomega]. On paper it should have been a sweet ride...it looked well engineered, but in practice it was a dog....slow and hard to accelerate.

I have several bents with 14' chains and I have yet to have a single chain related problem. If you want a shaft drive bike for the novelty of it go crazy, but you are trying to solve a problem that doesn't exist.

I have several bents with 14' chains and I have yet to have a single chain related problem. If you want a shaft drive bike for the novelty of it go crazy, but you are trying to solve a problem that doesn't exist.

The chain on my trike is almost 14' long, and I agree that it's no less efficient than a bike with a 6' chain.

I'd still love to see a recumbent with a shaft drive integrated into the main tube, that would be sweet...

I agree with vik. Chains have their drawbacks, but they're still in use because nobody has found a reasonable substitute. Anything to replace them would be heavier and less efficient. Wasn't somebody on this list working on a hydraulic drive a few years ago?

OTOH, I've seen chain-drive bents using internal gearing to eliminate derailleurs.

Chains have their drawbacks, but they're still in use because nobody has found a reasonable substitute.

Maybe you're right. Otherwise, you'd think shaft drives would be adopted universally.

It seems to me that the major objection to derailleur systems is the chain misalignment issues. With the very long chain of a bent, these problems are minimized.

buy a bmx bike

Get a Cruzbike and use a normal size chain. Jack

It seems to me that the major objection to derailleur systems is the chain misalignment issues. With the very long chain of a bent, these problems are minimized.
Definitely less problems shifting. The angle of the chain entering the front derailleur cage varies with rear gear choice, but the angle is reduced from that of a conventional bike due to the longer run.

Each link on the long chain also grinds through the cogs fewer times per mile. The only negative I've had is loading my EZ1 onto a hatchback rack - one tube/clamp must pass through the chain when loading or unloading.

I've never ridden a recumbent, but I am intrigued.
However, looking at the available recumbent bikes I'm struck by the length of the chain. Good grief, that looks like a multitude of problems just waiting to happen.

I'm also not a fan of derailleurs. Yes, I know, they've been around longer than I have, and are proven mechanically sound. Whatever. Don't like 'em..... What do you think?
Long recumbent chains don't cause any more problems than the shorter chains on regular bikes do, really. The weight and the extra cleaning are about the only drawbacks.

If you want to get rid of deraillers you can, by using a Rohloff hub ($1500) and a Speed Drive ($500), but then you're looking at spending two grand for those two parts alone. And you're still stuck with a chain, though it's possible you could use a belt-drive if you could find a kevlar belt the right length.
------
The problem with putting shaft drive on bicycles has always been the same: the gearwheels wear out. The physical gears need to be fairly small to fit into the overall constraints and small gears need to be held in perfect alignment and run in an oil bath in order to last very long.

Some of the gearwheels used in car and truck transmissions are fairly small (even for big vehicles) but they're run inside the transmission case or transaxle--where they are always held aligned and running in fluid.

Building an oil-bath transmission for a bicycle is not real easy in itself--and it's very difficult to build a bicycle that won't flex under hard pedaling, so you can't keep the gears aligned real well.
~

Never had a problem despite a long chain on my long wheel base. A driveshaft would be heavier and more expensive! Not that I'm against progress but 'it it ain't broke, don't fix it!"
Don't be afraid of a longer chain with a bent, though. It's not a problem, other than it's a bit longer to clean, which is certainly no big deal! When I bought my first LWB I was thinking that the long chain (and cables) would be tougher to tune and require more fiddling around, but after thousands of miles I can reassure you it just isn't so!

I'm wondering how the engineering would work with a shaft that can increase and decrease in length as my bike frame flexes while I ride. I can actually feel if flex like a long steel beam when going over some bumps. I don't think a drive shaft would work for that.
While my local LBS wrench can replace a cassette with no problem, I wonder how many of them can blue the gears to set the contact area when they need replacing.

You could get a chainless bike and cut the parts you need and reweld it all together into an AtomBLASTER
http://www.geocities.com/atombikes/blaster.html

A shaft drive recumbent would be incredibly heavy, expensive, and inefficent. Your talking thousands of dollars for something lousy. People keep making the same mistake anyway.

Shaft drive on a bicycle was obsolete 100 years ago. I'm not exagerating.
It has been tested and used over, and over, and over, for more than a century.

How much would a shaft drive for a Long Wheelbase 'bent weigh?

about 22 big macs or 19 whoppers or 79 french toast sticks, depends on what measuring system you prefer.

about 22 big macs or 19 whoppers or 79 french toast sticks, depends on what measuring system you prefer.
Is that metric? Oh, the french toast would be metric.

about 22 big macs or 19 whoppers or 79 french toast sticks, depends on what measuring system you prefer.


Is this going to be on the final exam? :D

I'm studying for all three. ;)

- heavier

Hi Vik! I must disagree with you on this one. With a standard DF bike, the relatively short chain doesn't weigh much. On a 'bent, there is LOTS more chain. A carbon-fiber drive shaft would probably weigh less.

- more friction - non-standard parts

I question the friction and agree with the non-standard parts. ALL new technologies start with "non-standard parts." Is the benefit worth the cost? Maybe. Nobody that I know of has really explored a shaft-drive 'bent. BMW uses shaft drive on their motorbikes (as do a number of touring bikes) and has experienced no problems. With modern gear technologies, the friction may not be an issue either.

If you want a shaft drive bike for the novelty of it go crazy, but you are trying to solve a problem that doesn't exist.

I must politely disagree again, Vik. External drive chains must remain lubricated to function. The lubrication picks up grit, grime, and dust that not only reduce the efficiency of the chain but also contribute to accelerated wear on all chain-rings and cassettes. Yes, the problem can be controlled with maintenance, but a sealed, shaft-drive system would eliminate the problem completely.

The fact that no commercially-successful shaft-drive system has yet been made doesn't mean that it can't. While shaft-drive may never succeed on diamond-frame bikes, it would seem that a recumbent might benefit significantly from the technology.

Cheers!

BMW uses shaft drive on their motorbikes (as do a number of touring bikes) and has experienced no problems. With modern gear technologies, the friction may not be an issue either.

You'll notice you don't see shafts on any 100cc bikes. You see shafts on motorcycles with big HP outputs, certainly big compared to a human with output measured in watts. So they don't care if the driveshaft wastes a few horsepower. For touring and general riding, losing 2-5 hp is a good compromise to chain maintenance. You'll notice that when getting all the power to the rear wheel matters, as in the 'pocket rocket' models, they always use chains.

Anyway, this is all just pie in the sky. We're not the ones designing new stuff; unless someone here has access to lots of equipment to fabricate one-of-a-kind parts for an experimental bike, we're only allowed to use what we can buy off the shelf. Which limits our choice to chains. (Pick your favorite brand, though.)

Actually, motocycles with high HP engines have chain drive for less power loss, but higher torque output engine motorcycles tend to have shaft drive.

Hi Vik! I must disagree with you on this one. With a standard DF bike, the relatively short chain doesn't weigh much. On a 'bent, there is LOTS more chain. A carbon-fiber drive shaft would probably weigh less.



I question the friction and agree with the non-standard parts. ALL new technologies start with "non-standard parts." Is the benefit worth the cost? Maybe. Nobody that I know of has really explored a shaft-drive 'bent. BMW uses shaft drive on their motorbikes (as do a number of touring bikes) and has experienced no problems. With modern gear technologies, the friction may not be an issue either.



I must politely disagree again, Vik. External drive chains must remain lubricated to function. The lubrication picks up grit, grime, and dust that not only reduce the efficiency of the chain but also contribute to accelerated wear on all chain-rings and cassettes. Yes, the problem can be controlled with maintenance, but a sealed, shaft-drive system would eliminate the problem completely.

The fact that no commercially-successful shaft-drive system has yet been made doesn't mean that it can't. While shaft-drive may never succeed on diamond-frame bikes, it would seem that a recumbent might benefit significantly from the technology.

Cheers!

Here are some thoughts on your comments:

weight: if you compare just a carbon fibre shaft to the chain on a bent it seems like the shaft would be lighter, but that is not realistic. Besides the shaft you need to make the bent stiff enough that it doesn't flex as was discussed by Doug5150, then you need to add a sealed case and an oil bath. Add all that up and I think the shaft will be heavier.

friction: chains are very low friction and the added dirt/grime of road riding doesn't significantly change that with some lubrication

non-standard parts: for the foreseeable future bicycles will be chain driven and if you own a shaft drive bike you'll only get parts online from the manufacturer. fine until you damage something 100 yards from a LBS and can't get any help or you damage something and have a big ride the next day. Not something I am keen on unless there is SUBSTANTIAL benefit to be gained and with shaft over chain there is no significant benefits.

maintenance: I oil my chain once every two weeks + after riding in a heavy rain storm for a prolonged period. This takes very little time and is inexpensive. Once every two years I throw on a new chain. If a sealed shaft bike saved me this effort it would be a minimal gain in my opinion.

repair: chains are easy to repair with minimal tools and spare parts. What are you going to do when your carbon fibre shaft breaks or the drive gears get damaged?

Like I said above I love gadgets and new technology so if you want a shaft drive bike because you think they are neat - cool. I'll oooo and ah all over your bike, but lets not pretend that a chain drive bike & especially chain drive bent is suffering from any major problems.

Regarding BMW motorcycles - I spent a considerable part of my life riding touring motorbikes your statements are untrue. BMW shaft drive bikes offered the same pro/con as shafts on bicycles would - lower maintenance, but the rider/bike was screwed if the shaft failed as field repair was not possible. That meant that BMW riders traveling off the beaten path had to carry a spare drive shaft. I always rode motorcycles with chains for the same reason I would ride a bicycle with a chain: they work, are not prone to breakage, they are cheap and efficient, spare parts are available everywhere and they are field repairable. Also factor in that a motorcycle frame is rigid with the suspension taking up road shock - a much better scenario for using a shaft. Not to mention the fact that with an engine powering the bike weight is not quite as critical as with a bicycle.

A CF drive shaft still needs steel ball bearings and the gears required to turn two 90 degree corners. The gears should be hardened steel. The shaft needs to change length if the bike flexes or the boom can be extented. This is accomplished by one shaft inside another that are splined together so it can get longer or shorter. All that is not light.
THEN! you need a transmission to change gears. The chain was part of the gear changing mechanism. You need an internally geared hub. The geared hub weighs as much as all the parts you took off and costs as much that the whole group. The internally geared hub has friction losses that need to be added to the shaft friction losses. It adds up. It's not just the shaft, it's the whole bike.

So the whole thing with a CF drive shaft weighs more anyway.

It's hard to sell a heavier slower more expensive bike. If you are making one for yourself be prepared to spend a lot more than any bike costs just to make a drivetrain.

Take a DF shaft bike for a ride first.

The long chains on bents don't cause any problems anyway.

Ok Ok Ok!! :roflmao:

There's nothing WRONG with chain drive. In fact, I concede all the advantages listed - It's cheap, it's available, it's easily repairable, it's the lightest, it's the most efficient.

That doesn't mean that someone smart (obviously, not me...) can't come up with something better. In fact, I predict that in time, someone WILL come up with something better. The "better thing" may or may not be shaft drive. As of now, it looks unlikely that the shaft will take over, but only for now.

Just because we can't imagine it doesn't mean it isn't possible! Just wait & see.

....There's nothing WRONG with chain drive. In fact, I concede all the advantages listed - It's cheap, it's available, it's easily repairable, it's the lightest, it's the most efficient....
Well really, shaft drive's only got two problems--putting the power into spinning it at one end, and getting the power out of it at the other. It can't easily be used with the current system of gears that most bicycles have, so you're looking at changing around a lot of pieces just to accomplish it.

At one point in time, cars used to have exposed chain drives.
I'd hope that bicycles will lose the exposed chains someday, but I'd still bet it's a long ways off.
~

....
The long chains on bents don't cause any problems anyway.

I find with my Vision R32s-with their long chainruns-I need to stop pedalling if I travel fast across bricks or cobblestones else the chain gets thrown (although this might diminish with a fder).

You'll notice you don't see shafts on any 100cc bikes. You see shafts on motorcycles with big HP outputs, certainly big compared to a human with output measured in watts. So they don't care if the driveshaft wastes a few horsepower. For touring and general riding, losing 2-5 hp is a good compromise to chain maintenance. You'll notice that when getting all the power to the rear wheel matters, as in the 'pocket rocket' models, they always use chains.

Anyway, this is all just pie in the sky. We're not the ones designing new stuff; unless someone here has access to lots of equipment to fabricate one-of-a-kind parts for an experimental bike, we're only allowed to use what we can buy off the shelf. Which limits our choice to chains. (Pick your favorite brand, though.)

I've got a folder with belt drive. While it does slip under steep climbs, if you've committed to going the internal gear hub route, the clean greaseless maintenance free belt approach is compettive with chain, and superior on a folder. WHile harder to find belt components and pricier than chain, components are around.

You have to appreciate that a chain and derailluer combination is a combined "open air" manual transmission and power transfer/drive shaft.

When you figure that modern internal hubs - Rolf and Shimano Nexus are very new in bicycle years and do not compete well in capabilities to the chain and derailluer system in terms of gear inches and weight, its going to take some major changes to materials/weight/construction before they approach the capabilities of a chain.

My 10 speed Tandem and Single bike components shift very well - No need to change something that is not broken.

Just recently had transmission fluid leaks at 6K followed by a torque converter failure after 12K miles on my Van. Nothing I could fix myself. Good chance an internal hub failure (like that has ever happened?) or a shaft drive failure on my bicycle and I would be stuck. Nothing much can go wrong with a chain and I know can fix it myself if I am in the middle of nowhere.

I find with my Vision R32s-with their long chainruns-I need to stop pedalling if I travel fast across bricks or cobblestones else the chain gets thrown (although this might diminish with a fder).

That is a small problem that is very easy to solve. It's not really a chain problem, it's just lack of understanding of chain drives.

Ok Ok Ok!! :roflmao:

There's nothing WRONG with chain drive. In fact, I concede all the advantages listed - It's cheap, it's available, it's easily repairable, it's the lightest, it's the most efficient.

That doesn't mean that someone smart (obviously, not me...) can't come up with something better. In fact, I predict that in time, someone WILL come up with something better. The "better thing" may or may not be shaft drive. As of now, it looks unlikely that the shaft will take over, but only for now.

Just because we can't imagine it doesn't mean it isn't possible! Just wait & see.

That's what they said about chain drive bikes more than 100 years ago. It's a mature well understood technology. Everyone and his brother has tried chain drive, shaft drive, and (ugh) belt drive. They have been sold and made and designed by good engineers. But the laws of physics still are the same.

Something better can come along, but it would have to be totally different than what is available now in technology. The bicycle is different than a car or motorcycle the prioities are totally different. Most of the people that bring this up have no idea what the problems are.

You can buy a shaft drive bike today, or ride one. Search the forums for lots of owner reports, they all have the same problems. This comes up every few months. There are photos and owner reports on the forums. You can buy a slower, heavier, more expensive, bike and enjoy it all you want. I rode a new shaft drive bike at a show. Members here own plenty of them.
I love some of my slow heavy bikes. I love the slowest, heaviest, thing in my area, Bailey's trike. :D But. I modified the drive train the gearing and the tires to make ii much much more efficent. The way it was it was like pedaling a battleship. I love my 1952 Schwinn Spitfire, but I don't ride it much, I can't ride it very far It's more work.

It's up to everyone to like what they like. But to sell them is another problem. To sink money into something that is hard to sell is bad thinking.

Google shaft drive bicycles and you will find the place in Taiwan that makes them, photos of all kinds of bikes including full suspension, folders etc. a close up of the shaft assembly, and Dynamic bikes and other retailers. This stuff is all over the internet. Read up on shaft drives on Wikapedia.

Here's one for a DF bike.

http://img524.imageshack.us/img524/9783/p2zm0.jpg

love the discussion. i haven't seen this forum so active since... well, never. it's almost like the SS/FG forum over here.
but what I'm wondering is, what about an internal chain? i think that would be awesome. sure, it would be cleaner and whatnot — but it would also look more elegant.
has this been done?

...what about an internal chain?...has this been done?

Yes - Fully-enclosed chains are not unusual. The advantage is that cleaning and lubrication become almost unnecessary. I've never seen a chain run inside the frame, but there's no reason why not if the frame is convenient to the chain-line.

I've only had to give the barrel adjuster on my LWB bent ONE quarter turn only once or twice in the last 2 years (and about 4000 miles) Did it the other day. The chain idler is 'floating' which practically eliminates shifting problems. I doubt that the extra chain weighs enough to have any significance as bents tend to be a bit heavier than DF bikes.
A drive shaft bike would be interesting, but I doubt if it would be practical. Some motorcycles are now belt driven. I always wonder if a bike could be designed like some 4X4's with a continuously variable transmission of some kind, presumably belt driven. But like a drive shaft it would be heavier and way too much trouble for what it would be worth.
Chains work so well it's tough to beat them.

Ok Ok Ok!! :roflmao:

There's nothing WRONG with chain drive. In fact, I concede all the advantages listed - It's cheap, it's available, it's easily repairable, it's the lightest, it's the most efficient.

That doesn't mean that someone smart (obviously, not me...) can't come up with something better. In fact, I predict that in time, someone WILL come up with something better. The "better thing" may or may not be shaft drive. As of now, it looks unlikely that the shaft will take over, but only for now.

Just because we can't imagine it doesn't mean it isn't possible! Just wait & see.

I totally 100% agree with your prediction. Sometime in the future, someone will come up with something better than the chain drive bicycle. Very astute observation. I can't see how this won't happen....:D :D :D :D

I have a linear recumbent tandem with half a mile of chain that flaps and jumps. It spews water when it is wet and dirt when it is not. It is not a perfect solution but it is a workable one. There are lots of industrial applications that use light weight, tubular drive shafts and I would think that given the length of chain (particularly with a tandem bent) there would probably be some weight saving with a shaft drive. There is no necessity for a shaft drive to use small gears and there is certainly no necessity to use internal hubs but as someone has already pointed out that is what is being manufactured so that is what is being used. Theorectically the two changes in angular momentum necessary with a shaft drive will always make it less effecient than a chain drive.
All that being said if someone is working on a open hub light weight shaft drive train I would very much appreciate being kept informed. If anyone knows a machine shop in northern california that might be able to build same I would appreciate the name.
thx

Wasn't somebody on this list working on a hydraulic drive a few years ago?

Hydraulic drive is just asking for power loss. It is a matter of fluid dynamics. Allot of power is lost to friction inside the plumbing and in the fluid its self. Hydraulic drive systems are only used when none other will work, and only slow speeds are needed.

- Bryan

I recently came across a fellow riding an expensive looking road bike. It had a shaft drive, the first time I had ever seen a bike with one. Having been a long time motorcyclist with shaft drives on my last 5 bikes, I asked him how it performed. He responded that the bike was brand new but was going back to the LBS for retrofitting because the shaft drive was defective. I'm not sure what the problem was because he was able to ride the bike as is. Most of my recumbents only required replacing the chain after 5,000 or so miles. Even using two and a half chains on my trike was not a great expense compared to the initial cost of a shaft drive.

Check out http://www.3sat.de/3sat.php?http://www.3sat.de/nano/bstuecke/08514/index.html It looks like a working prototype for direct drive planetary geared recumbent. The page is German though.

Here's your solution: http://www.bikeforums.net/showthread.php?t=388790

Another issue I see is that some recumbents wind up with an extra bend or two in the chainline, which is perhaps a minor friction loss. But making that extra bend with a shaft drive would be a much bigger bother.

That forum you referenced had no gearing. I dont see it as very practical but maybe slightly amusing. I would like to hear some more about Thomas Kretschmer’s design.

I meant it for amusement, not as a serious answer to the question at hand. :)