| Author | Message | ||
     Skeenix |
I was reading through my most recent copy of Machine Design, (which the CityX was on the cover last month) and they have a product spotlight on a CVT (Continuously Variable Transmission) for a bicycle application. Essentially this is the same type of technology used in snowmobiles to vary the gear ratio(s) except that rather than using a belt and pulley system it uses a toroidal/planetary system. Check out the demonstration on their website, it's pretty cool. (You will need broadband as well as Media Player.) http://www.fallbrooktech.com/video/cvp-lg.wmv I'm very interested in this type of technology and how it would apply to motorcycles. Nissan uses another type of this technology in their Murano, however I've never driven it so I can't comment on it's performance. Also, to my knowledge, this type of transmission has never been used in a production streetbike, yet Leonardo DaVinci sketched this idea out hundreds of years ago. I'm curious what you would think about driving a motorcycle without a clutch and gear shifter. I would love to have a transmission that would keep you in the sweet spot of power and torque throughout the whole range of speeds without having to up- or downshift. It seems that this device has many advantages over traditional transmissions. If you want to find out more about this stuff there is also info on the How Stuff Works website. Comments? Impressions? | ||
| Mikej |
I believe the newest MiniCooper also has a tranny similar to that as one of their options. | ||
| Bud |
as i work with a volvo dealership, ( use to be daf aswell ) i worked a lot about the cvt transmision bought rubberband pull system en steel-band push system ( btw. a dutch invention from Huub van Doorne ) but i would not want it on a sports bike or any motorcycle , it takes a while to get used to the little or no engine braking and the high non changing rpm's level while accelerating got to fly now, but wil be happy to dig up some info gr, bud | ||
| Davefl |
Ridley make a cvt trans motorcycle.  http://www.ridleymotorcycle.com | ||
| Whodom |
Skeenix- The concept has been around for a long time but think it's only recently gotten to the point where a CVT can handle sufficient horsepower to make them practical for higher horsepower applications. "Road & Track" had a big article on them in the last year or so. A CVT would definitely take getting used to. I believe that Nissan went so far as to add artificial "shift points" because people were weirded out driving a car with no perceptible gear changing or change in engine RPM. It seems like CVT's would be most beneficial for engines with very narrow power bands and little bottom end torque. Not much benefit to them on a Buell. | ||
| Skeenix |
I guess the Honda Silverwing scooter uses a belt CVT as well. Hmm... I had no knowledge of the Ridley bikes, I guess I've been following sportbike development more closely than the cruisers. This is the only CVT sportbike design I could find. http://www.maxmoto.co.uk/gilera_850_ferro.shtml | ||
| Spike |
My dad bought a Murano a couple months ago and I've managed to rack up some miles behind the wheel. It definitely takes some getting used to. It basically feels like your clutch is slipping the whole time. Stab the throttle and the tach with smoothly wind up to near redline and stay there as the car accelerates. It's light-years ahead of the conventional automatics I've driven, but still feels too disconnected to be used in a performance application. It's worth noting that I truly hate automatic transmissions and my opinion is a bit skewed. | ||
| Mikej |
A general question: Take three cars, one with a CVT, one with a traditional automatic, one with a manual tranny, all else being equal, and take them to the drag strip. Which one comes in first, second, third? Just curious how this CVT tranny is when you really have to tromp on the throttle like when merging on a freeway or something. Maybe I just need to go test drive another MiniCoop.  | ||
| Jlnance |
FWIW, It's very easy to build an electrical CVT system (though it goes by a different name.) A diesel locomotive works that way. Engine turns generator, generator powers motor that turns wheels. The power to weight ratio of electric motors tends to be fairly poor, so this would be a terriable thing to try and put on a motorcycle. But it might work out nicely on a hybrid car. | ||
| Whodom |
Mike, I think that at least theoretically the CVT would win out, since it allows the engine to maintain the precise RPM for best horsepower with no "dips" when the transmission shifts gears. In the real world, I'm sure there are losses in the transmission that offset this gain. I'm not sure which transmission would really do best at a drag strip. IIRC, the main reason they have gained in popularity recently is because of fuel efficiency. | ||
| Skeenix |
Theoretically the CVT is 25% faster to reach say 60 MPH with all other variables being the same other than the transmission. | ||
| Sportsman |
Old Honda Pilots, a 400cc dune buggy oddesy kind of thing, had that kind of deal. They were really fast too. | ||
| Wyckedflesh |
uhm...Audi has been using the CVT on their cars for a few years now, including their SuperTouring race cars. Polaris has been using the CVT on their ATV's for years. Mike, MotorTrend did a dragstrip comparison of an Audi with a manual VS the CVT model with the CVT model edging out the manual by a full second. They didn't have the same model available from the year before equiped with a "standard automatic" but the auto was just as quick as the manual the previous year using the manual shifting rather then letting the car choose the shift points which Motortrend pointed out as being rather soft and ment more for economy then spirited driving. | ||
| Mikej |
Interesting, gonna have to go test drive one. Thanks for the info. | ||
| Johnnylunchbox |
I am totally guessing here, but in order for a CVT to win against a conventional standard tranny, it would all depend on how fast the CVT was able to adjust its gear ratio. It would seem that being in the meat of the powerband is a good thing, but if the CVT can't change fast enough, then the variable RPM's of the standard tranny are going to win. So the question is, can a CVT change gear ratios faster than an engine with with a standard tranny can increase RPM's? My head hurts. | ||
| Wyckedflesh |
Johnny, what your not understanding is that a CVT changes its gear ratio as the RPM rises. 1 RPM increase is enough to change the gear ratio on the CVT. When the CVT reaches the end of its ratio range, it then changes the final drive ratio and starts the process all over again. The CVT is geared so that its in the perfect ratio for where it is at the RPM range. A CVT doesn't HAVE to be in the meat of the powerband in order to work, it is already in the proper gear ratio for that specific RPM. | ||
| Tramp |
i gotta agre with 'bud'. i've been a shadetree volvo nut (240 & 740 ser.) for 25 years, now, and while i love the old 'solenoid overdrive', i'd hate to have any of that ilk on any but a tour iron. on the bmw dry clutch, it'd be do-able but........ .....why? i mean, if the existing sportbike transmissions are such a drag, heck- get an SUV...... | ||
| Wyckedflesh |
If you seriously wnat to know what a CVT would be like on a bike, go test ride a Polaris 500ATV with a CVT...go ahead, pull that trigger  | ||
| Mutt2jeff |
It seems like these transmissions would be ideal for freight trucks and other heavy load vehicles. | ||
| Rokoneer |
Both of these machines have CVT's. Like Wycked says if you pull the trigger on the yellow one (which is a 1972) the front tire will pass over the top of you it has so much power. One huge bonus of a CVT in this application is that you are always in the correct gear for any situation. The learning curve is a little steep initially, but once you master it you would be amazed at how effective they are.  | ||
| Phillyblast |
I used to work at a Subaru dealership, and drove a Justy with a CVT. Tiny little 3 cylinder car, but it flat out scooted around town with the CVT. It's already been stated, but you tromped it and it revved and went. Great for city driving. My mom had one with a 5 speed, and it was geared really short to make up for the lack of low end - really annoying first gear, felt like you should shift halfway into an intersection when the light turned green. The CVT eliminated that little safety hazard. | ||
| Blake |
Been waiting for someone to raise this topic...  No comment. | ||
| Wyckedflesh |
I will admit to a perverse sense of wonder on what an XB would be like on a track with the Polaris engine... | ||
| Trojan |
I remember seeing a picture of a Piaggio/Gilera factory project road bike quite recently with an 850cc V-Twin and CVT transmission. It was in the MCN some months ago but hasn't surfaced since. | ||
| Grndskpr |
Work on these all the time, they have been standard in the Kawasaki Mule line for some time, and really dont have great longevity, seems the counter(?) weights that activate the CVT unit will actually wear out the unit Kawasaki has used both the EX500, and some sruiser twin motor to poer these utility vehicles, but like i said, at or about 1000 miles, i have to replace them, easily done, with little mess, but not sure how long it would last mounted to a bike It very interesting to see an ex500 motor with the trans removed from the case, and a single output shaft to the cvt(they could have made the motor much smaller) but other than worn CVT units, they have been the most reliable vehicles we have used Something to consider, as a rule, once the unit starts to rattle(sounds like somethings loose) its time to replace the belt and cvt Just random thoughts R | ||
| Newfie_buell |
That Green Bike is very interesting? What is it???? | ||
| Edstevens |
Newfie_buell The green motorcycle is a Rokon Trail-Breaker. It is a 2 wheel drive motorcycle with a 3 gear or maybe I should say three range automatic transmission. It is very quiet with 15 inches of ground clearance. The first time I saw one was in the late 60's in Elkins, WV at the Forest Festival. There was a demonstration of hauling (dragging a log), climbing up a steep slope and to finish drove the Rokon up into the bed of a pickup truck. They appear to have changed a little but not much from the model I saw demo'ed. Their web site is http://www.rokon.com and please look under accessories that are offered for them. The Jordanian army has a version listed their too. | ||
| Skeenix |
I guess what I find interesting about the previously mentioned product is that it seems to address many of the failings of the traditional belt and pulley style CVTs and I could easily envision one being used in a sportbike. It's a novel approach with a lot of potential. I tend to like simple, elegant, engineering solutions. | ||
| Rokoneer |
Newf, a better source of REAL Rokon information is at www.rokonworld.com. Rokon Inc, the manufacturer, is in a real downslide the past few years with the quality control aspect of the 2WD's steadily diminishing. 'Rumor' has it that you will see another similar, yet much better, 2wd motorcycle very similar to the Rokon on the market before too long... | ||
| Bud |
http://www.insightcentral.net/KB/faq-cvt.html F1 http://www.ritzsite.demon.nl/DAF/DAF_cars_p17.htm | ||
| Charlieboy6649 |
The fastest quad I've ever seen at competition hill in Glamis, Ca was a custom long swingarm Suzuki 500 Quadzilla frame that had a Polaris transplant. He increased his lead dramatically with his opponents every shift. Nobody could beat him up the hill... | ||
| Charlieboy6649 |
Seems to me the same could play out on the street  | ||
| Bud |
I the old day’s there was a rally cross rider named jan de Rooy ( hint Dakar rally trucks ) And he build nice DAF rally cars, as you know DAF is the inventor off the CVT, So jan de Rooy had some factory support, he build a DAF with a 185hp cosworth engine using the CVT as transmission 4wd, The plan worked out so well that he could not be beaten on the track, while the other rider all complained about it , Jan said ok, you know what , I’ll give you all a head start like 50 meters or so.. knowing he still hade by far the fastest car under acceleration due to the properties off the cvt Needles to say he still won http://en.wikipedia.org/wiki/Van_Doorne%27s_Automobiel_Fabriek http://8w.forix.com/altpower-cvts.html gr, bud ps. I would like to try it on the drag strip | ||
| Davegess |
When th eCVT first came out in cars they were msotly in very small low power jobs to help alleviate the belt life troubles. Interesting review by LJK Setright some 20 years ago, he could get the jump at stoplights very easily even againest much faster cars because they are so efficent. The odd thing was they woudl drone, they would go to the engines torguw peak and stay there so you wouldn't get the typical rising engine note as you accelerated. He found that a little hard to take. Did have fun getting one up to near top speed on the motorway and than on long flat streches he would very slowly back of the gas and the car would not slow down, just lose rpm's as the cvt changed ratios to try an maintain speed. He said you could optimise the RPM speed ratio and return simply amasing fuel milage numbers. | ||
| Bomber |
now THERE'S a name I havn't heard in a long far -- whatever happened to LJK Setright? he was one of the most entertaining and literate motojournos of all time, in my book still have a piece he wrote called "You can shift, but can you dance?" great stuff! | ||
| Road_thing |
Yeah, Setright was an entertaining read. Hadn't heard his name in years. Yet another reminder of how old we're getting, huh Bomber?? I Googled him up and found this: http://www.granta.com/features/2004/12/setright rt | ||
| Bomber |
thaks fer the link, Thang -- great to hear he's still confounding the rubes, ain't it? | ||
| Davegess |
Yeaj when LJKS retired from CAR I stopped subscribing. Not nearly as fun to read it without him. | ||
| Kim |
Go to http://www.gizmag.com/go/1909/ for an article on the Burgman 650. Pics and a good explanation of the cvt. |
