| Author | Message | ||
     Blakeaspencer |
Does anyone know why buell has not developed a zero torsional load rear wheel? The brake could be similar to the front wheel design and the drive can be hung off the side of the rim. This doesn't seem all that complicated, but why hasn't it happened? Am I missing some important piece here? | ||
| Pwnzor |
Maybe because they just don't need that much braking power on the rear wheel? It would look cool as hell though... | ||
| Crusty |
How big would the front sprocket have to be if the rear sprocket was attached to the rim? | ||
| Hughlysses |
Matthew- I'd think Blake is mainly thinking about the drive side rather than the braking side. Crusty has a good point. You could probably compensate with primary gearing so that you don't need a huge front sprocket, but I think you'd still wind up with a wonky-looking final drive. The additional length of chain required to wrap around the big sprocket might offset most, if not all, of the weight savings from having a lighter wheel. | ||
| Ratbuell |
The blast was close as far as sprocket size goes. And goofy looking. If Erik hasn't done it...I'm certain there's at least one valid reason. Aside from the fact that the rear doesn't "need" as much of a diet as the front wheel does. Acceleration transfers weight ONTO the rear. It doesn't steer. It just needs to accelerate...and to a lesser extent, brake. And to that matter...a ZTL rear brake would simply be too much rear brake power. Unless it had a single piston caliper with a piston the size of a pencil eraser. Which would be a waste of the design. | ||
| Sifo |
Just guessing here, but unlike the front where you eliminate the weight of an entire caliper, and disk, you can't do that when the standard is already a single caliper and disk. Then you either need a huge drive gear (as I understand it, the huge drive gear on the Blast limits cornering clearance), or you have to engineer a carrier that connects the small drive gear to the rim. Of course, that second part has already been done. It's called the rear wheel. Going the huge drive gear route also gives you a big heavy gear. | ||
| Jaimec |
I've seen designs on custom choppers where the rear wheel is driven by a roller, but that HAS to considerably shorten rear tire life as the roller is driving the rear wheel through the tire (which still has to deal with braking, cornering and driving force). Done more for looks than any kind of performance benefit or weight savings, I think. | ||
| 1313 |
Just guessing here, but unlike the front where you eliminate the weight of an entire caliper, and disk, you can't do that when the standard is already a single caliper and disk. That's where my thoughts are as well... 1313 | ||
| Froggy |
I've seen some custom bikes with the rear brake rotor mounted not on the wheel but instead to the front sprocket, I imagine that reduces unsprung weight without causing too many other engineering headaches. | ||
| Aesquire |
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| Natexlh1000 |
Freshly lubed brakepads too! | ||
| Crusty |
That hot dog looks interesting... | ||
| Natexlh1000 |
They should put a handful of those doubledown things into a cider press and sell the result as a "protein shake". | ||
| Crusty |
You know; I've never eaten one of those "Double Down" chicken things. I've had a mild fascination about them, but I've never tried one. They're probably like the fascination I had with stuffed crust pizza from Pizza Slut. When I finally got one, it was a starchy, barely edible mess. Just about what I'd expect from Pizza Slut. I bet the Double Down is more of the same, but I'd still like to try one, one of these days. I'm not in a big hurry to do it, though. | ||
| Aesquire |
I haven't tried the Hot dog thing. The "regular" double down is delicious. 2 small chicken breasts as the "bun" around a small slice of bacon & some hot sauce. Awesome! I hadn't had KFC for... decades, and I had a brake line on my Ford Van blow pulling off the exit at Lyndora PA. ( Butler ) Since I actually usually leave a little room ahead of me I got slowed down and made it around the corner instead of causing a multi car crash. I drove a few blocks to the Monroe Muffler shop, and left the van to be fixed, and there was a KFC down the street. I saw the Double down on the menu, and had one. Then I had a few more over the next few months before the Food Nazis started complaining it was Satanic ( instead of a low carb masterpiece ) and now KFC teases it's customers by promising to bring it back, and spreading rumors that the store over in the next town has them.. ( but they don't when I get there ) It's a great con game, you go in hoping for the Satanic Meal and walk out with a foam cup with old mashed potatoes and the broken chicken nuggets. Brilliant! There's also a bacon cheese burger version, with fried chicken buns. That's got to be nasty. I've just seen it advertised. | ||
| Froggy |
Crusty, no need to rush as it is too late, the double down is dead. The double down dog isn't even in the US oddly enough. You are right about Pizza Hut though, and it is a shame because the stuffed crust concept is great, I wish Dominoes or something offered it too. | ||
| Airbozo |
Dominoes Death Disk. Not had one in decades. Pizza slut either (loved that name when I first heard it a looong time ago). You can order the double down at many KFC's, it just not on the menu anymore. Maybe because the cute girl behind the counter likes me... KFC is my only fast food weakness and addiction. I have curbed it a lot over the last few years though. I used to be able to eat a bucket in 2 sittings, but those days are long gone. | ||
| Adrenaline_junkie |
The last time I looked both tires were leaned over when a motorcycle was in a turn. So the gyroscopic effect (affect?) does pertain to both wheels. Reduced wheel mass would be beneficial to both suspension performance and rotational acceleration (speeding up or slowing down), unless you are riding a hard tail. A ZTL brake caliper for the rear wheel would be tiny, as noted earlier. The last time I checked, tiny was usually light. Another good thing. This leaves me thinking that the primary problem is the drive chain or belt running out that close to the perimeter will cause corner clearance issues. Maybe if the ID of the rim was toothed instead of smooth and a drive gear was located on the inside edge of the swing arm. I know that having the rim do double duty as both a rim AND a drive gear is probably ridiculous but then so was putting fuel in the frame a few years back. I'm sure there is a good reason why Erik hasn't done it yet, but I don't think we have mentioned it. Maybe it would take to long to change a tire out during a pit stop or the crazy drive I described doesn't provide desirable anti squat properties when accelerating out of a corner. And maybe a huge rim mount sprocket provide too much anti squat. I sure am glad I read this thread though, something interesting to ponder for a change. Back to the hot dog discussion. | ||
| M1combat |
I'm pretty sure it was mentioned by 1313... On the front you can reduce mass. On the rear you are already looking at a very lightweight brake setup (relative to the front) and you have the added challenge of trying to also reduce the weight of the drive side of the equation without making it heavier. Driving the hub may be a solution... but at what cost to efficiency? How much outright power would you lose doing that? | ||
| Adrenaline_junkie |
I believe that the major mass reduction is in the mass of the wheel itself. You get to use those dainty spokes like the front wheel has if you don't have to transmit any torque. In fact, I seem to think I read somewhere on this forum that that is the basis of Erik ZTL patent. You can use a ZTL brake without violating his patent, but if you reduce the weight and torque capacity of the wheel you are violating the patent. That's just my memory so I could be wrong. | ||
| Adrenaline_junkie |
That being said, I'm sure you are correct that the drive system connected to the rim would be far to expensive and heavy to justify the mass that could be removed from the spokes. | ||
| Torquehd |
The blast was close as far as sprocket size goes. It's been over a decade since I owned a blast... IIRC, the cornering angle was reduced on the sprocket side due to the sprocket being so large. ??? Am I wrong? | ||
| Sifo |
Driving the hub may be a solution... But then it wouldn't be ZTL... | ||
| M1combat |
Sorry I meant the rim. | ||
| Jaimec |
The wheel lightness comes from the fact that the spokes do not have to be strong enough to support the braking torque. On the rear wheel the spokes would also have to support the driving force, as the rear sprocket is mounted to the hub. I've seen hubless rear wheel systems (see above) but they don't lend themselves well to anything but styling exercises. | ||
| 1313 |
I'm pretty sure it was mentioned by 1313... On the front you can reduce mass. Actually, it was brought up by Sifo in this thread first. Erik covered this exact topic - the driver for the ZTL front brakes (weight savings) - during his talk during the EBR Reunion event at Dreyer's EBR just South of Indy in September. I've never been a naysayer about the ZTL brakes, but some of those who are would've likely got a MUCH better understanding by listening to Erik's talk. It probably wouldn't convince them all, because a little understanding of the process of engineering is needed, but it definitely gave the impetus for the ZTL setup being weight savings - which would be awfully hard to realize on a rear wheel setup. Now if the naysayers has only heard what one of the biggest benefits for radial mounted calipers actually is they'd probably blow a gasket, or begin even further naysaying... 1313 | ||
| Blakeaspencer |
Ok I was more interested in the drive side. The sprocket/pulley does not need to be massive. It could be held inward from the rim via longitudinal spokes. The brake could then be mounted however to reduce weight, such as on the front pulley (which would also add to mass centralization and less unsprung weight). I can see how this would add weight to the outer portion of the rim, but the hub and spokes would be reduced substantially. | ||
| Aesquire |
The majority of stress on the rear wheel is power not brakes. Don't know about your bike but my Cyclone has a rear brake that's just a token. A dab to settle the bike in corners to settle the chassis. ... which mostly I don't need. And hold the bike at a light. Otherwise it's useless. The weight transfer on hard braking means my rear wheel just barely skims the ground. I barely touch the rear. ( & i can raise the rear off the ground at will with a few more ounces of squeeze. ) So to lose hub & spoke mass like the front needs you to do rim mounted sprocket or drive connection. That's got to weigh more in the end. I posted the KFC picture for the caption. Not the food they only sell occasionally to trick you into walking in. The compromises mean rim mounted brakes to save weight aren't worth it in the back. Clever idea. Logical progression. Not worth it. This is science not politics. When the theory is disproven you make a new one. Now if you made the rim a rotor in the electric drive? No belts, chains or shafts. You could even use the Buell patented rim brakes as the rotor instead of burying magnetic bits in the rim proper. That way you wouldn't need a rear brake caliper or hydraulic bits at all. What would look like a multi piston caliper would be the swing arm mounted drive. | ||
| Jaimec |
I seem to remember another way of driving a hubless rear wheel was via a hydraulic drive that forced fluid through the wheel assembly to make it rotate. Again, it was more for the funky looks of a hubless rear wheel than any performance benefit. | ||
| Sifo |
Ok I was more interested in the drive side. The sprocket/pulley does not need to be massive. It could be held inward from the rim via longitudinal spokes. The brake could then be mounted however to reduce weight, such as on the front pulley (which would also add to mass centralization and less unsprung weight). I can see how this would add weight to the outer portion of the rim, but the hub and spokes would be reduced substantially. I'm not sure exactly what you mean when you say the sprocket/pulley can be held in place via longitudinal spokes, but aren't you pretty much describing a conventional wheel? |
