| Author | Message | ||
     Timmy2shoes |
Aaron, et al.... those of you who are technically inclined, please refer to this link, I would like your input on this debate. http://www.sacborg.com/ubb/ultimatebb.cgi?ubb=get_topic&f=1&t=000402 Thanks, Tim | ||
| Aaron |
Well, I don't see a debate, but you sure as hell raised an interesting point. Think pickup in 4wd on a clear paved road ... don't turn a corner! I'm assuming the difference in wheel diameters has already been compensated for in the relative gearing, has to be. But how much differential in wheel speeds do you really get on a bike when turning? Hmmm. Then there's the effect of tire wear, and tires of the same size in different brands not being exactly the same height/circumference. It seems like there *must* be slip in the system. I don't know anything about hydraulic motors, is it inherent to their design? Blake? Pretty cool stuff. Should enable more power. That's always good! AW | ||
| Sportyeric |
Re: 2WD R1. Bloody engineers! Always adding complexity! There's a great article in the current Cycle World about the advantage a twin has on the track (besides displacement): peak torque is far from peak HP so if you spin it up. torque decreases and its easier to get under control. Here's Yamaha adding more doodads to a bike that already has two too many cylinders and three too many throttle bodies! | ||
| Blake |
I'm with Eric. How much unsprung weight do you think the front wheel drive system adds? How much sprung weight does the front wheel drive system add. Seems to me, for a sport bike, it will be VERY difficult for the advantages to overcome the excess weight. The hydraulic drive is probably much like an automatic transmission's torque converter. I dunno. Interesting though. In 10 years, who knows. It may be a must have for the go fast crowd. | ||
| Raymaines |
I've only read the MCN artical about the 2X2 R1 but I think it sounds pretty neat. Especially for a Sport Tour kind of bike that might see a wet road now and then.. My favorite paragraph from the MCN artical: "At the moment, the roles a bike’s front and rear tyres play in acceleration, cornering and braking are clearly defined – and more than anything else it is the limits of their grip that define the performance parameters of any bike. Two-wheel-drive has the potential to share the tyres’ tasks more equally – giving any bike fitted with such a system a potentially huge advantage in outright grip." | ||
| Aaron |
Well, I think the 2WD concept is pretty cool. Technology for technology's sake doesn't do anything for me, and you see that all the time. This looks like it really brings something to the party. | ||
| Buellzebub |
kewl, finally a bike i can ride in the snow | ||
| Bomber |
Aaron . . .there will be slip in the hydraulic drive, if it's designed in . . .if not, as someone posted, I think of my ol C5 jeep in fourwheel low in the dry turning a corner . . . .didn't wanna, not even a little but the slip is easily allowed for, and might even allow for differential drive (split torque front to rear), which could, with the addition of further doo dads, be programmable . . . . goodness . . who ever thought that writing manuals for fork lifts would come in handy, eh? | ||
| Timmy2shoes |
2wd.... but what about low speed maneuvers.... like, turning into a parking space? with the bike upright, and the bar at full lock?? I just think that the forces applied would upset balance.... and I somehow cannot figure how 2wd would help all tha much when cornering (at speed)... I would figure that a front tire (in ANY) situation, only has so much traction, and would also think, that if under accelleration, woud be more likely to break traction ("push" the front end) than a non-powreed wheel, that simply rolls along the road, "going along" wih the friction of the road. I dunno... just thinking out loud, i guess.... | ||
| Aaron |
Excellent points. Are you, by chance, an engineer? No offense. | ||
| Roc |
My understanding is that the issues present with the diferent types of locking differentials in auto applications are a result of the differing tracks of the two parallel tires when cornering, traveling different diameters and different distances. The different distances traveled require slippage in the differential or at the tires. On a bike the tires could maybe be required to travel different distances at very low speed - this probably could be handled by the hydraulics allowing for the difference. At high speed it seems like the tires would be traveling the same distance and this would not be an issue. This is my guess. I think that if this were an issue in corners than Yamaha would not be pursuing it and the test rider would not be able to honestly give such a report. If such differential action were required in a motorcycle then a two wheel drive system, unless very complex and well done, could induce slides. If this system ends up doing well what will it require of tires. Bigger front tire with a smaller wheel? | ||
| Buellzebub |
slip in hydraulic motors = heat, where they gonna hide the cooler and hyd. tank for that critter, best case schenario. i see the hyd. package adding a minimum of 75 pounds with a closed loop system. [just a guesstimate] variable displacement pump, motor, lines, hyd tank, cooler, filters, oil,etc. still, should be good in the snow I R NOT AN ENGINEER... after a minimum of 4 years in school, they still won't let them drive the train, what a rip off | ||
| Ralph |
Maybe somebody can explain to me why a two wheel drive bike wouldn't lift the front end during excelleration and wheelie just like a standard bike? You can't get any more power to the ground than is possible already. Weight transfer wins. For instance in heavy braking manuvers where the rear brake is of limited value because of the lightend load on the rear end, how exactly is this going to get more power to ground via the front end? I see no value except on an off road bike where you have to get as much traction as fast as possible and a tourer where weight transfer is less of an issue because of lower power to weight and the simple fact that they aren't riden in the same aggresive manner as sport bikes. In other words, tech for tech sake. bighairyBAHHUMBUGralph | ||
| Aaron |
As I understand it, instead of having 140hp at the rear wheel, you have 140hp minus the amount that was redirected to the front. Hence it doesn't wheelie as bad (if a wheelie is bad!). | ||
| Ralph |
Hey Aaron, have you ever seen somebody drag race a front wheel drive car? I have. I even helped them set it up. Over a few weeks of stupid hard work we got it down a few seconds. End result, I have very strong feelings about weight transfer and putting power to the ground. When I first saw a hydro front drive about a year ago it made sense. It was on a dirt bike. On a sport bike it is little more than a curiosity. I have no doubt the problem of power transfer can be taken care of so that each wheel has all the power it can handle. That is nothing but time and money. The problem of utility and better function over what exists I see no answer for. All wheel drive cars have advantages, but cars are not motorcycles. Lets give that the bike 140 hp minus the amount given to the front wheel, lets say half. Will a bike wheelie with 70hp? My S1 says it can be pretty easy to hold down, if you want. But, my S1 also says the front end gets pretty damn light. Will that super light front end handle 70hp? No way. 5? I doubt it. So, we either rob the bike of nearly 70hp (call it gutless) or we throw the power back to the rear wheel, which now has to push the extra weight of all the hydro crap (call it a dog). But, all of ones time is not spent in dragrace starts. So, here we are going through a turn, as you excelerate through the turn weight is being transfered to the rear end. True even if you have a hundred percent of the power coming from the front. So now, instead of the lightening front tire just having to handle the forces of the turn it must also handle having to excellerate the motorcycle, all the time getting lighter and lighter the more power it puts down. Two things will happen, more power is (again) directed to the rear wheel or the front washes out. So, my snap judgement is, it sucks. the bad part is I haven't even read the article, I can't pull it up  bighairyJUDGMENTALralph | ||
| Blake |
"I can't pull it up" TMI! TMI!!  Maybe if we think outside the box a little, we might imagine that with a little more weight on the front wheel (forward weight bias) and being advantageous when accelerating through the turns, the 2wd might be useful. I just don't see it being able to overcome the deficit of the added weight. I'd think some creative work with aerodynamics and movable surfaces to increase grip might go further. I've wondered if there might be some way to use aerodynamic forces to help counteract centrifugal (centripetal for the engineering purists) forces. Upon entering a high g force turn, the rider might activate a control surface that creates a left to right or vice-versa lift while leaned over. Sounds crazy huh. Whadaya thank BHR? (please no more about your current personal troubles.)  Blake | ||
| Roc |
On the Segway thread didn't someone mention a gyroscope in the front wheel for improved wheelie stability? How about this 2WD set-up? This is an experimental thing I think, a possibility for the future. A future with lighter bikes that have more power. Just a thought. | ||
| Djkaplan |
Interesting arguments. The dirtbike application is the only one I feel qualified to address. As an experienced off-road racer, I wouldn't think a powered front wheel would be of much benefit except at very slow speeds; Rokon Traibreaker type speeds. Perhaps with a very sophisticated processor to control torque split for different situations - maybe. I could certainly see it being an advantage in all out acceleration in a straight line with very slippery track conditions. But there are to many situations on an off-road bike where it is necessary to keep the front end light or keep it raised altogether. On an off road bike, there is little or no trail braking on the front end. I think it would be asking too much for the front end to steer and drive. On a car, it makes sense though. | ||
| Aaron |
Back in the mid '80s, Audi fielded a Trans-Am team, and used AWD. Folks estimated they were as much as 100hp down on the domestic V8's of the day. They won the championship. Their ability to put the power down coming out of the turns more than offset the horsepower disadvantage. They were especially fast in the rain. SCCA eventually changed the rules, went like NASCAR with essentially only one way to build the car (front V8/rear drive/live axle), and you don't see off the wall stuff like that in Trans-Am anymore. I don't know if any of that is relevant or not, just thought I'd share it. AW | ||
| Anonymous |
HEY NOW!!! Wait a minute...You can't build a better mouse trap...That would put all the old mousetrap builders out of bussiness. No we'll ban your mousetrap. That way we can kill mice the old fashioned...slowly | ||
| Ralph |
Roc baby, whenever I ride my bike is equiped with two gyros. The front wheel and the back wheel. Every time you turn you are fighting those forces. Think about what would happen if you added another. DJ, I was hoping there was some real use and could only see off road or touring. Looks like off road is out too. Blake, I agree those would be some interesting ways to go. Unfortunatly, in racing the rules are so strict they can't play with things like that. And only is racing does it have viable use. . I can't pull it up 'cause the girlfriend is busy with it Aaron I knew somebody was going to bring up the all wheel drive cars and how fast they move. I love 'em personally. But you know that just doesn't mean squat. Two wheels don't turn like four. The forces during a turn on a four wheel vehicle are concentrated on the two outside wheels. Not so with a two wheeled (inline) vehicle. Nony mouse, before a mouse trap can be of any use, there have to be mice. I think there needs to be a real unlimited class in racing, just for things like this. If it does have any real value it would survive. bighairygirlsgotitralph | ||
| Anonymous |
Not knowing much but having a little common sense, what about having the most hp up front with the back tire having just enough to keep up? Also, as far as potential wheelies / loss of control, when I was on a river rafting trip the guide said that as long as you're moving faster than the surface of the water you'll be okay. Not sure how that notion applies. My head hurts; I need another beer. | ||
| Jocklandjohn |
You know how some of these tarmac road rollers vibrate to make them apply more downwards force? Is it possible that making the front wheel vibrate evvveeeerrr soooo slightly when coming out of corners could make the downwards force applied to the road increase? Or should I just go join the mousetrap men for a beer and be quiet.....??? Hey get me that beer ready boys...... |
