Motors Motorcycle Mayhem

The long answer is to imagine a normal wheel; a toothed gear is affixed in the centre to transfer from a chain or belt, and a brake disc on the other side to provide the opposite effect. To get a hubless wheel, just expand the size of the shaft inside the normal wheel until it occupies all the space that used to be taken up by the spokes and is mated to the rim of the wheel. The brake disc and gear are still attached to the wheel, they're just stretched around the 'shaft' too so that they're much bigger. For example;

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On this particular example, I can see a brake disc on the transmission gear preceding the chain drive, but in our example, on the other side of the wheel, a gigantic and very shallow brake disc is gripped by a calliper right at the edge of the wheel.

The short answer is badly. The much greater diameter of the 'shaft' means much, much higher bearing speeds, and that means terrible NVH. This is why hubless wheels never made it big, and are still really the preserve of concept cars and handbuilt and rarely ridden choppers.

 

If you think of it in terms of a very large bearing it works just like any other shaft drive rear hub

Thats not the transmission it's the cylinders, the transmission is tucked under the crankshaft. As for the V4, I ride a BMW, I'm not even going to dignify that with an answer (If you know bikes/bikers you'll understand, there's no zelot like a BMW zelot)

Thanks

You're probably right there, do you have any references? I always like increasing my knowledge about this sort of thing. I had always thought it was due to a hubless wheel increasing un-sprung weight.

Moriquendi

 

It might not apply quite as much to a shaft-driven hubless, but just imagine the huge increase in required speed of the chain on a chain-driven one.

I like that design a lot, but to my (untrained) eye it looks a bit busy somehow.

 

I'll try and render an image of the other side, without the front and rear swingarms theres much less going on. Part of the "busyness" of it probably comes from the fact that motorbikes generally wear their insides on the outside, if you look at a car you see long,sweeping body lines and not the complexity of the engine/drivetrain. On a motorbike however everything's on view, you can't escape that as it's part of what makes a bike a bike so you have to work around it and try to make everything "fit" into a cohesive visual whole and thats not that easy.

Can you think of any particular areas that make it seem busy?

Moriquendi

 

Stereotypes: they exist because they're true

 

Whatdoyouknow? you ride a KTM FFS

Moriquendi

 

I think the double arm for the front wheel is part of it - it's wonderful, but somehow clutters what is usually a very sleek area of a motorbike. That's a big signature part of it though, so it's not really up for a swap.

Another part is probably the big humped fuel tank, it adds something to the profile that I can't quite get to grips with.

 

Yep the double arm suspension is a primary part of the design though I should really have put it on the opposite side to the rear swing arm, from a balence point of view it would have been better too. I guess people are so used to seeing standard forks that anything else looks a bit strange, BMW Duolever for example. Bikes like mine with Telelever avoid it but only because it's basically standard forks with a single extra brace. With the fuel tank I was trying to get a reasonable volume into a shape that would still allow a proper racing tuck. At the moment the volume is around 21 liters which is still pretty small if you're talking about a road going machine. I guess it is pretty extreme though, I may try and shift the volume down a bit, make it wider at the bottom and lose some of the bulge. One of the reasons it is as it is though is that the main frame is also the airbox, with the front and rear suspension bolting onto the engine the main frame doesn't really have any major forces through it so I decided to save some space and integreate the airbox. The downside of that though is the it has to have a fairly large volume to be an effective airbox meaning the fuel tank appears larger than it is because of the frame/airbox running through the middle. Ill render some pics with the body panels removed so you can see more of the arrangement of things.

Thanks for the input though, sometimes you can get stuck in a particular train of thought and not see things that to other people are glaring.

Moriquendi

 

Heh, you've clearly put rather a lot of thought into the layout of it, not just some random concept!

 

Nope, not a random concept, in fact this is my fourth or fifth concept but I keep getting a "better" idea for this bit or that bit and have to start again...

Moriquendi

 

I had an idea on how the chain/belt hub-less wheel would work, I was a lot more curious on how the power is transferred on the Shaft/hub-less combo.

Lol, yea I had no clue about the BMW bike loyalty, as I really don't meet that many bikers who ride BMW's up here, I think the most BMW's I've seen was a few on a dealership floor, and a handful of riders on the road occasionally.

I have a slight Yamaha preference from my motocross days , but other than that I just like whatever works the best for what I'm doing.

I think something that might be adding to the bikes busyness is the angular nose. It doesn't quite fit when the rest of the motorcycle is all curves. But the nose on its own is definitely cool looking, it's just kinda like trying to make a dolphin look like a stealth bomber, it might be amazing, but it just isn't quite right.

 

Essentially it's just a bevel gear except that the gear on the wheel is very large and has a hole through the middle. I don't really agree with you about the angular nose, I don't really think it's that angular though it doesn't fit particularly well with the rest of the body work and I'm not all that happy with it. Doing the body work has probably been the most difficult part of this bike for me.

The thing about BMW is that they have their own characteristic engine, like HD with the V-twin and Ducati with the L-twin/desmodromic valves, for BMW it's the boxer engine. Nobody else makes a boxer motorbike and they have some advantages over other engine configurations, bucketloads of torque and low vibration primarily. The downside is that the cylinders stick out the sides but for 99% of riders that's not a problem (99% or riders will never get their knee down that far anyway) and they protect your knees from the loving caress of high speed ashphalt. The long and short of it is that it's the best engine in the world, no the universe, and I wont hear any different alright?

Moriquendi

 

Thx...

I had it at the dealers to get it soldered,then sealed with this tank sealing and anticorrosive stuff from the oldtimer restauration sector, but he convinced me to get it epoxied. still has the oldtimerstuff in it anyway.

The dealer did something wrong though, he's had to reseal it on guarantee two times afterwards
Now's the third time....probably can't get the epoxy out anymore to solder it properly this time.

 

Ok, I have some more pictures for you people now that I have vista 64bit installed and can utilise all my RAM.

First is a picture of the right hand side of the bike with all the body work.


Second is again the right hand side but with all the bodywork removed so you can see the gubbinz.


Finally a picture of the left hand side without all the bodywork.


Comments and critisisms gratefully accepted.

Moriquendi

 

Would it be possible to shop in a skeletal or wire model to show the riding position?

 

This should give you a rough idea of the riding position but it's based on someone my size (6'5") which is well beyond what most bikes are designed for.





Moriquendi

 

The red box is the battery? The weight is a bit far to the back me thinks (engine's are moved forward to the max. normally. This would also allow for a long rear uuuh whats the english word rocker arm? Linkage?
(looks pretty long as it is, though)

*sigh* been too long talking technical english...

 

You mean the swingarm? I don't know, looking at the riding position I'd still want to move the engine forward a little to get my knees away from the cylinder heads.

 

The red box is the battery and is further forward than it is in most bikes, also it's weight is so small that it doesn't have much effect on the center of gravity. The engine is placed as far forward as possible and should give a mass distribution of around 56%44% front:rear which is about ideal. The rear swingarm (thats the word you're looking for) is pretty long anyway and due to it's geometry it behaves as though it were even longer (because of the parallelogram linkage).

Yeah the riding position isn't ideal but then engine cant be moven further forward because of the clutch housing at the front interfering with the front wheel, it's a problem that I will address in the next version.

Moriquendi

 

Your design looks much more elegant side on with the driver position shown. I did not like the humpy tank but when you see the riding position it makes sense. I know FA about bikes btw.