The weight issue is funny. As always people think that the traditional BMW-stuff is heavy. I compared the weight of swingarm, beveldrive/sprocket, driveshaft/chain on a R80GS and a F650GS Paris Dakar:

R80GS shaft 12,4kg
F650GS 9kg

That’s not to bad is it? …… Well if you need to carry a spare set of sprockets and chain the weight for the chain-bike will be 12.3 kg! Still 100 gram lighter but you need lubricants, a few chainlocks and maybe some tools.

Conclusion: Shaftdrive is not necessarily heavier then chain and sprockets!

Sidenote:
Small things like chain guard, chain followers and so on are not included in the weight stated above.

So:
Weight – The same
Cost – Shaft is less expensive in the long run
Maintenance – OldBmw has some good points here, personally I would prefer a few hours job every 100-150.000 km then the hassle with a chain.


Who cares?

Since 1977,all of my bikes have been shaft-drive,CX500,6 Goldwings,5 BMWs.

I've done "serious" miles on all of 'em.For instance,my latest bike,bought new on August 1st '07, has done just under 11,000 miles!

I have never had a single problem with any shaft-drive.

Chains belong on bicycles!!

I have to agree with AliBaba, the weight difference isn't big, there is a small weight advantage for chain drive, but not as big as many people think it is.

The main con for shaft is the power loss, which is approximately 18%, chains drives have approximately 11% power loss from the crank. So this clearly dictates shaft drive isn't the best solution for very high performance road racing bikes. But for our consumer use adventure and adventure touring bikes, where 7% power difference wouldn't be noticed, I think we can argue about the cons and pros of each system.

Personally I prefer the shaft-drive. On BMW paralever, you can repair it on the road too, if you know how to do it. You need to carry a main bearing and/or a main seal just in case. They cost less than a good chain set, weight less and take less room carrying them with you.

Very nice armored assault vehicle , imagine if it was a chain drive and you had to ride home that is 200kms away w/o cleaning and lubricating it, like I often do with my GS - how much chain wear it'll cause? Also if mostly riding on dirt and gravel roads? Even the "sealed" X- or O-ringed chains will give up faster in dirty conditions. Closed systems (both shaft and some enclosed chain drives some older bikes have) are the best there I think in terms of longevity and wear. If riding only on clean tarmac on Western-European and N-American clean main roads then high quality (D.I.D., Regina few other) chains last relatively long (up to 30Kkms, some even more if you aren't a very hard handed rider and clean/lubricate it after every 500km, or after every day when riding in rainy days), but it's a hassle in any case. Your rear wheel will be oily with dirt glued on and your girlfriend (maybe you too if you're too nasty on oiling the chain) will have oily boots, whether you have Scottoiler or you prefer to clean/oil it yourself and you have to keep an eye on it constantly anyway: overall condition, wear of the chain and sprockets, and constantly check&adjust chain slack... In comparision, any 20,000km or more manitenance intervalled (only oil change needed) shaft drive looks very convenient, since you even don't have to touch or look at it in between the maintenance intervals.

In the end of the day each system has it's advantage and disadvantages. Everyone has their own personal requirements, comfort-levels, technical skills and risk assessment in their minds to choose the one that suits the best, IMHO anyways.

Here's mine:



Mine's now at 73Kkm and not a single problem.

Honda did make a V twin with a shaft drive. The St110, and the Deauville as well as the CX500. But depending on what type of travelling you want to do depends on what bike you choose.

As you said most off roaders dont have shaft drive (apart from a few) for weight as most people say and to keep the bike slimmer and other reasons.

As for choosing a bike give us a possible price you would want to spend on (if you dont mind) the bike and we might be able to give you a few bikes we would think about. and what type of terrain you want to go on, road, bit of off roading, hardcore stuff

I plan to go to morroco and i just bought a Yamaha Xt660r for me i find it a great bike, cheap to run, comfy etc but it has a chain when my old bike a deauville had a shaft drive. But there are plenty of things out there to help stop you throwing money at them like scott oilers, degreasers to clean road crap from the chain etc etc

Seem to have spawned quite a discussion here on chains and shafts! After reading through all the posts the only thing one can conclude, as with all these sort of discussions, there are pro's and con's for both systems!

Biking wise I have no experience with long touring outside of europe, but i imagine that if you decide to drive over from up here to SA, it would be fun to get into less familiar type of biking. Probably not the hard core stuff, but some semi offroading, a bit of desert etc seem like a pretty cool experience! So that would probably mean a tenere/africa twin/kle etc enduro style bike. The near daily chain maintenance still scares me off a bit, but if that is what it takes and it can be done without too much problems, it seems like a minor price to pay for a wicked experience!

cheers for al the input

Paul

[QUOTE=Margus;168730]

The main con for shaft is the power loss, which is approximately 18%, chains drives have approximately 11% power loss from the crank. So this clearly dictates shaft drive isn't the best solution for very high performance road racing bikes. But for our consumer use adventure and adventure touring bikes, where 7% power difference wouldn't be noticed, I think we can argue about the cons and pros of each system.
end quote

This is not a fixed thing Margus. On the diesel bike forum where bikes often run with a max of 9hp, transmission loss can be substantial. For instance the old Enfield gearbox when filled with grease as recommended consumes over 25% of the crankshaft power. Switching to 90 grade oil halves this, with a further decrease of power absorbtion when using 50 grade oil. The new (since 1995 or so) 5 speed gearbox on 50 grade oil will often allow a bike to go an extra 10mph, as it absorbs very little power.

Many modern bikes run the gears in the very thin synthetic engine oils which reduce drag to a minimum, wheras the bmw's use separate gear oil of 75/80 weight. Worse for BMW's is that the gearbox is directly coupled to the engine, so there is no primary reduction. This means the input shaft turns 2-3 times faster. to compound this problem, the output shaft is offset to drive the shaft. This forced BMW to use a gearbox that not only spins fast but final drive is via transverse cogs, all of which conspire to drain power. Old Gearboxes and most car gearboxes usually lock the input to the output on the same shaft, so in top gear power is not trasferred by energy wasting gears at all. This normally can easily be checked by looking to see if top gear is shown as a 1:1 ratio. Final drive ratio should always use the least amount of intermediaries for highest efficiency ( and probably component life).

Hmmm...

I did dynoed my GS and guys who've dynoed most of the bikes and have extensive experiences on this field said the BMW-spec gearbox/paralever drive-train is within the power loss spec of most of other modern shaft-drived systems (or my over 60Kkms done GS performed well above factory performance specs to "cheat" the dyno machine results calculation), including japanese bikes with wet clutches and gearboxes floating in the crankcases in a very thin engine oil. I use spec oils only: usually 75W-90 GL5 both in gear- and bevel box.

The pro for BMW engine+gearbox system is all the shafts rotate parallel, which, at least in theory, should give the best mechanical efficiency and longevity - i.e. lot of unusually high mileage BMWs, Honda STs & Goldwings, some Guzzis. Engines where 90-degree turns are done have their own "uneffective" losses. So maybe that's why on dyno the BMW specs the same as other shaft-drived bikes that have all the friction going on in the thin engine oil, but with 90 degree turn at one point before it's transferred into shaft(?) I.e. bikes like Yamaha Diversion, Suzuki GS or VX, Honda XLV etc.

I agree the power loss ratio does vary, that's why I use the word "approximately" anyways. Depends on the temperatures of oils, mechanical details (i.e. Klingelnberg-Polloid spiral pattern in BMW paralevers), ratios, oil viscosity etc. But with modern shaft drived bikes the power loss is around 18% range running in common transmission oils in bevel boxes. I'm sure Enfields etc with different oils (even full of grease variant as you said) have different results and probably have more power loss than the modern siblings.

If you feel that the BMW is lazy because of all the powerloss in the driveline (which I personally don’t think is bad compared to an old beaten up chain) there are plenty of modifications that can be done to increase the power.

Somewhere in the North western corner of Tanzania my pannier more or less fell of when I landed after an unplanned jump. Wonder if chain and sprocket would have made it?



BTW. I also have a bike with chain :-)

Wonder why they don't use SHAFT drive on Moto-cross bikes???

They jump a fair way!

Martyn

I guess they don’t have problems with panniers falling off?

MX is a bit different. They spend a few hours with service after they have ridden a few kilometers, but if that suits your travel-style it might be the right choice.

No, the problem with the BMW gearbox is it outputs top gear via gears. so it loses power by sending it across two shafts and through gears. Most gearboxes do not do this. they transfer power direct because the input shaft IS the output shaft. so no gears or layshafts carry power, therefore no power loss at all when in top gear. This is why a typical BMW engine lasts three times longer than a typical BMW gearbox.

Can you explain how a single 1:1-rotating-shaft-to-engine-speed-on-both-ends can be input and output shaft at the same time in the conventional (not on automatic or semi-automatic or variator type of) gearbox? Only possiblity is if the final drive somehow "switches" between secondary and input shaft (that rotates 1:1 to engine speed) if switching between final gear and all other gears.

My mind says they may be parallel and at the same reflected co-ordinates on both sides of the gearbox (one shaft rotates "over" second), but input and output shaft have to be separated with gears anyway to change gear ratios.


Honda gearbox has a separate input and output shafts:




Yamaha gearbox, separate input and output shats:




Suzuki gearbox, separate input and output shafts.




BMW R-series bike gearbox, separate input and output shaft (same as all others):



Or a modern car gearbox:

This illustrates even if the input shaft is the output shaft with separated rotation - the power will go through the gears (they'll not just "stop" to completely isolate any friction) even if it runs 1:1 with crank ratio in the end.


Surfing in the Google I can't find a manual gearbox that nearly 100% transfers 1:1 rotation power (by "stopping" all the secondary shaft(s) rotations) into output shaft w/o touching the secondary shaft(s) that changes the gear ratios...? I may stand corrected here.


The "bulky" gearboxes maybe didn't last long on old airhead BMWs (i.e. like some had bearings failures at around constant 50Kkms etc reports, needed modification to last longer), but on the newer oilheads there are doing some serious mileages on stock gearboxes. I.e. Hank Hits 400,000 Miles on His BMW R1100GS - Lone Star BMW / Triumph Motorcycle Dealership - Austin, Texas,

After 640 000 kilometres and he's still on original gearbox (even pistons and rings aren't changed, no major repairs aren't done on the bike).

Hey guys, be kind. some of us still have to use dialup.

Margus

If you look at any old Brit bike, or the new Enfield gearbox you will note that the drive train is arranged like this := The engine output sprocket drives the primary chain to a the clutch hub.
There is usually about a 2:1 reduction here. The clutch hub is free to rotate when the clutch is used, but locked to a shaft when the clutch is closed. This shaft goes from the primary chaincase into the gearbox and is the gearbox input shaft. In the space between the back of the primary chaincase and the input side of teh gearbox sits the gear sprocket which drives the rear chain. The gearbox sproket is mounted on splines on a bearing mounted collar that is free to rotate over the input shaft. The collar extends a little way into the gearbox. There is a gear here that takes power from a layshaft driven gear in all the lower gears. In top gear however, instead of driving via a gear onto the layshaft and back out, the output collar is locked to the input shaft via dogs on a gear which is in the input shaft and splined to it. This locks the output gearbox sprocket to the input shaft. It is possible that some gears may be meshed and rotating, but they are idling and not carrying any power. This is one reason these geaboxes whine (straight cut gears) in all gears except top. It may also account for the higher speeds attained with less power than is needed with some newer designs with offset output shafts. After all, a Tiger cub produced only 10hp so energy conservation was important. Or put it another way, a 650 cc triumph Tr6R with 40hp is about 5 mph faster than a BMW 800cc bike producing 50hp. I am not trying to criticise anyones design, They all were (and still are) compromises based on what the conditions were expected at the time of design and marketing fashion. Nowadays bikes have so much power losing the odd 20hp is of no consequence (except to range/mpg) In the case of the BMW, having a centrally mounted input shaft forced them into having an off set output shaft, in order to clear the rear wheel. When they made the K series.. I expect that the reason for lying the engine on its side was to put the centreline of the engine crankshaft inline with the output shaft, thereby making it easier to construct a longer lived gearbox. But I do not know, never having owned a K series bike, but that is what I would have tried to do.

Hi Alibaba,
I just cannot imagine what it is about a couple of sprockets and a chain that adds up to 9 Kg.
Can't say I have ever weighed suchlike though.

I would "imagine", again I don't have weighing scales to hand, that the current crop of BMW shafties are heavier than the earlier models - they just look bigger and, therefore, heavier.
So, is it a useful comparison to take an old bike alongside a current production model (including the next generation of F650GS)?. I quite understand that you are riding one, so you have a personal interest!

I do like the way that BMW are prepared to manufacture bikes with all 3 common(ish) drive systems; shaft, chain and belt. In the next few years, we may see more of the chain drive models appearing, or belts for that matter.

Apart from this, I would just like to remind the original questioner that the chain drive bike can have it's gear ratios changed pretty easily - I don't hear or read of shaft drive owners fiddling with their gear ratios.
That's why the "racers" will always have a whole pile of sprockets and gearboxes for the various circuits - lets see how BMW are going to deal with this when they go racing!!

__________________
Dave

That's because the swingarm are included (for both shaft and chain). The swingarm are very different on shaft vs chain bikes.