That’s a fair point, I hadn’t thought of the Diavel. Makes you wonder why it isn’t a possibility for the Multi?
I did as much searching as I could, without any bias (I hope) and the chain is by far the most efficient, then comes the shaft then the belt. But it seems that those data are a bit outdated and that the belt has closed the gap to the shaft (or maybe went past it?). I did find a link (from a manufacturer of such systems for other applications) where it is stated that the efficiency of modern belts reaches 95-98 % (and there was a link to a PDF that was dead), although it referred to non toothed belts as far as I could see. To be honest the only gripe I have with chains is the oily mess. Everything else is to my eyes superior (in total) to other drive types. You may need to get the swingarm out to change the belt but hey ... if you do it every 100K kms (or more) then you can do a nice cleanup of the rear axle as well. Then I found this. Not relevant to motorcycling but gives a good insight on efficiency of synchronous belts. Maybe there are factors related specifically to motorcycling that reduce the efficiency in such an application? Also this.
shaft isn't more efficient than belt these days, and certainly nowhere near as efficient as chain. Chain is the easy option: pretty reliable, robust for most uses, and can be found almost anywhere. Shaft is ok for torquey engines, and where weight is less of an issue over long distance / low maintenance. It does have an impact on performance due to its mass. Belts are great if confined (i.e. in an enclosed are), but are less robust than both the above, and constrain power that can be applied through the teeth of the belt. This impacts on the rate of acceleration vs load applied, else the teeth on the belt don't last very long. Sprockets for belts are a bit dearer than chain ones, and belts are cheaper than chains, so overall not much of a difference price wise. That isn't the main issue on a bike though. The problem is generally to do with a belt being a fixed ring, no way to break and re-assemble it. This presents major issues since most bikes have the output sprocket close to the swing arm pivot point (makes chain tension more constant throughout the range of movement), and running inside the side of the frame, and sometimes through the swinging arm. This is usually because it provides the strongest construction of frame / swinging arm with least amount of flex. Using a belt would mean the need for replacement without having to take the engine out, and routing that doesn't pass through the swinging arm (so likely to rule out single sided swinging arms). If your really worried about chain losses, then these can be fiddled with too, O/X ring chains are great for maximising life but create more drag. This is why some racers will go down a chain width and run non-O-ring chains. Personally I'm happy to put up with changing a chain every 15k to 20k, and not have to worry about the thing too much
Talking to Dealer a while ago about belts v chains etc. the comments were "where have you seen belts or shafts in competitive bike racing (apart from the one make BMW races). Chain drives take less engine power and less weight than anything else at the moment." So what about the Diavel? "That is designed as a sports cruiser with the emphasis on cruising so Ducati do not expect them to do big mileages or extended hard riding so for low maintenance and aestetitics they chose a belt and in any case the belt is a consumable item, like a chain so unlikely to cause major warranty costs" Just saying and it seemed a reasonable answer to me.
The pre-DVT seem to deliver c150 RW on most dynos. And may be BMW are more realistic with their core numbers The S1000RR seems to deliver very close to their claimed numbers
guys,i was talking to a ducati manager and i undrestood that its not likely to see a v4 multi at 2020.the logical year is 2021.
I don't see how a chain is more efficient than a belt, every link creates friction as it articulates, noise and vibration are unwanted products caused by wasted energy.... something a belt produces very little of. A chain is more compact & quicker to change (with the right tools) than a belt - even if the frame has a removable section to allow belt replacement. I am on my 3rd belt on my Buell, first snapped at 22000 miles, second at 38000, I love the lack of chain noise, mess & no back lash/vibration from it, but would I want a belt on my Multi? No, I don't think so - stones puncturing the belt is a constant worry, and no amount of belt guards can eliminate the risk. I like the idea of a shaft, but my only experience of shaft drive was my first bike, GS 650 Katana, and quite frankly, that was pretty horrid with the effect that had on how it felt in corners. I dare say that they have come a long way since then though!!
Maybe so but if we're speculating on a V4 multi why not speculate on its final drive. This direction is not upsetting me. TB
Beef, belts are far more critical of tension and alignment. One of the big factors for efficiency losses on belts is the pre-tension that needs to be applied. In fact if you can reduce pre-tension to almost nill, toothed belts become more efficient than roller chains. The problem is they do not handle running like this very well, having a tendency to whip and jump teeth / jump off. This is why cam belts etc have tensioners, and why the tension is pretty important (more important than reducing the losses). Also toothed belts aren't totally maintenance free. In some environments dirt etc will get trapped into the tooth grooves of the sprockets. This can add additional tension, cause the belts to become noisy, and if you do nothing about it can cause the belts to snap. So maybe Admins need to move the 'final drive types' posts out into a fresh thread, and just leave a link to it here. I expect they have other stuff to do though. Discussing final drive choice is just as valid as discussing any other design decision we might like to see imo.
Looks like they kept the triangular shaped wheel rims but moved to larger strutts. Roll on the official announcement & details...
It’s a photoshop. An impression of what the front will look like tagged onto the back of a V2 picture.
