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Has anyone ever designed or manufactured and automatic transmission (automatic shifter?) for cycling? |
I imagine such a device would automatically change the gearing to allow the rider to maintain constant cadence or constant torque on the cranks. |
I used to daydream about the existence such a system many years ago when riding my first (battered, secondhand) racer as it was such an ordeal to change gears. |
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Wondering about that, and about what you said you wondered, I think the act of shifting is the problem, but the right to choose the exact gear you want, and the time of shifting, that is invaluable (imagine the bike "arbitrarily shifting" when you don't expect or don't want). Regarding that, shifting systems have becom... |
Automatic gearboxes tend to be heavier and have more friction (i.e. you would have to peddle harder to get the same result), which is why they're never used in cars when performance is important. Since peddling a bicycle is bloody hard work as it is, I don't think automatic transmissions are a good idea. The in-hub gea... |
It is not manufactured AFAIK. However it's certainly possible, my friend already invented it. However I would not use it, not because it would be harder to use or something like that. But rather because having control over the gear you're in is VERY valuable compared to a system that automatically chooses it for you. I... |
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6 Answers |
up vote 8 down vote accepted |
http://www.landriderbikes.com They were very heavily advertised several years ago but currently they seem to show up more on craigslist than on TV. |
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Lol. I had to laugh at the video on the site. But I do indeed see how they could be useful for older people who do not want to deal with shifting gears. – Keegan McCarthy Jul 17 '12 at 22:51 |
I knew someone that has one of these, they have hard time with it since you have to keep pedaling to keep the right gear. – Carson Reinke Jul 18 '12 at 17:11 |
Would you consider adding a summary about the hub system you're referring to and how it works? – amcnabb Mar 29 at 18:17 |
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Trek had a bicycle a few years ago named "Lime" which had 3 speed automatic gearing. I don't think it sold well. It used a gearing system called "Coasting" that was created by Shimano and actually controlled by a computer chip from signals from the front hub. |
"A dynamo is fitted on the front hub that gauges the revolutions of the wheel. It sends this information to a computer chip housed near the pedals on most of the bikes. |
From there, the chip, which controls the planetary gears located on the back hub, determines whether to shift up or down. All the chip needs to make its determination is for a rider to pedal four or five times, according to Shannon Bryant, Coasting project coordinator for Shimano." |
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I have ridden one - it used weights thrown out by centrifugal force and springs to move the derailleur in and out. Horrible is all I can say. Maybe it was me not being used to it, but things like not being in the gear you left it in, and less than smooth changes - which you have not idea when they are going to happen, ... |
That said, for cruising around a by someone who otherwise would not ride, and only on flat, even ground), its would do the job. |
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sounds terrible, I guess on 'flat, even ground' there is no need to change gears, so the problems go away? :-) – Ken Jul 19 '12 at 17:14 |
I assume that there are a variety of designs that provide automatic gearing--do you remember which particular type you tried? – amcnabb Mar 29 at 18:16 |
@amcnabb - sorry no, it was a long time ago when I was ignorant of basic bicycle components and construction. – mattnz Apr 1 at 6:20 |
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There have been attempts over the years, but never particularly successful. One I recall used a 5-speed rear hub that was shifted by weights on the spokes, similar to a centrifugal governor. |
I expect that, with the new electric shifters, there will be some new attempts at it in the next year or two. With a computer it should be possible to be reasonably "smart", especially if mated to some sort of torque meter. |
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Check out the new Autobike http://www.autobike.tv. It uses a CVT. |
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In its current form your answer doesn't really comply with the Q&A format of this site as we are trying to collect the relevant information here and don't want to have just a collection of links to other sites. Also it looks a lot like some commercial without disclosure. Maybe you want to elaborate a bit more about the... |
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There's the Nuvinci Harmony |
It uses the Nuvinci N360 CVP hub, which is a continuously variable transmission, meaning there are no shift points. The Harmony controller changes the ratio based on cadence, or it can be adjusted manually. |
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Would you consider expanding your answer to give a brief summary of how this hub works? – amcnabb Mar 29 at 18:06 |
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lucy in the deep |
Photon Mapping, Subsurface Scattering (translucency), Participating Media/Volumetric Scattering (fog-like effects), Phillips Spectrum FFT Waves (water), Perlin and Worley-based Noise |
Craig Donner |
For this project I wrote a ray-tracer from scratch, which I humbly named "Hikaru", which means "ray" or "light." No LRT or Miro code here.... It's all mine. Hikaru managed to grow from a simple ray tracer to a full global illumination renderer, all in the course of 10 weeks. It also makes a kick-ass bounding-volume hie... |
This project somehow managed to involve the following: |
The Road to Final Rendering |
Irradiance Caching/Gradients |
My initial renderings were of simple scenes, such as the above Cornell Box using irradiance caching + gradients. It only took several seconds to render the image. Irradiance caching works by assuming that the irradiance over a surface changes gradually, which is generally true for diffuse lambertian surfaces. The model... |
The model of Lucy I used is from The Stanford 3D Scanning Repository. The original .ply model had 14,027,872 vertices and 28,055,742 triangles in it, which was a bit much. In fact, I couldn't even load it on my machine. I tried a variety of programs to simplify the geometry, and finally settled on RSimp, a great little... |
Subsurface scattering was my next hurdle. I implemented the hierarchial method proposed in Henrik's second paper, which stores irradiance values distributed evenly over the geometry of an object in an octree. Unlike the octree used for irradiance caching, the one for translucency actually stores representative values a... |
That's a shout out to Rui Wang for his awesome rendering of a translucent dragon. In fact, his images were no small inspiration for my project. This one, of course, used direct visualization of the photon map, and wasn't really tweaked for perfection, but it was a good start. More translucent images to come. |
Volumetric Scattering |
This one took the most of my time. After reading the paper a few times I started to get the gist of the alorithm, and started to make some test images. |
As you can see, it wasn't all smooth going. Eventually I figured out how to get stained glass to work, and how to sample the volume photon map correctly. Getting the phase function terms in the right place, as well as going through equations for scattered luminance took some time. Playing with scattering and absorbtion... |
At this point, while trying to think of a scene, I decided that an underwater scene would make the best use of most of the algorithms I had implemented. But to make an underwater scene, I first needed water. Turbulence functions produced rather repeatable patterns, and were difficult to control. |
To really make good looking waves, I relized I had to do something more complicated. After reading several papers on waves, I settled on Tessendorf's Phillip's spectrum FFT waves. I ended up writing a little demo program to simulate waves. |
Rendering good caustics proved to be a formidable task. Because my scene was becoming so large, it was requiring a large number of photons (> 1,000,000) to produce even somewhat decent caustics. I implemented a modified ray-marching scheme to help directly visualize caustics, which produced better results, without stoc... |
The seafloor texture is another Worley function mapping F2-F1, with a gradient noise applied to the sample point to remove jagginess, to color and bump. The floor mesh was generated using the above heightmap (made using "Render Clouds" in Photoshop, then a few Gaussian blurs to smooth it all out). The wave mesh (not vi... |
I started adding things to the scene. |
Here's a pair of images showing the difference translucency makes in the image. You can see the light bleeding through lucy from the rest of the scene and the god-rays in the background. |
And once again, the final image. |
Removing 90/CQ speakers-front |
Ok, I just did this this weekend. |
First, pop off the grills from the top. A small flat screwdriver does fine. The speaker comes out from the |
top of the dash. You can then remove the original speakers with the one screw that is exposed. |
There are two tabs for the original speakers. The first is slipped into a positioning pocket and the second |
is the one that is screwed down. |
Not, after you are this far, the fun begins. Before I looked at the application, I bought a set of Infinity |
Kappa 42is, coax 4" quartz injection molded cone with silk dome Kappa tweeters. Nice speakers - |
surprising clarity and impact for such small speakers. Price is $100 per pair retail, I got mine for $50 |
through wholesale channels. Either way, superb speakers. |
But wait, what fun? Well, First the Kappas had a 4 hole square set up. I had to take the Dremel and cut |
off two of the ears and modify the two remaining so they matched the profile of the original. Then, on |
installation I found the extra magnet size and depth made installation about 1mm away from being |
impossible. I had to Dremel out a channel for the wires to drop down in the plastic base the speaker |
screws to and learn a pretty intricate ballet to get that chunk of speaker into the tiny little hole. |
It is complete, though. And sound is superb. I covered with the original plastic speaker grill, so |
appearance is still stock, but sound is not. I am in the middle of an extensive music transfusion in this car |
and right now, these 4" are the only ones set up. I have had people ask me what I had in the rear to make |
it sound so good... There is nothing in the rear, just these two little 4"s... |
Hope this helps and didn't bore anyone to death.... |
Todd - Akron, Ohio |
90 Cq |
Other lesser beasts... |
RSS Text Alerts | Mobile |
Bathroom design: It's all in the details |
(BPT) - It's most likely one of the top reasons you've been putting off that bathroom makeover or remodel - you're not sure where to begin. What should the decor... |
These questions, and many others, should be at the top of your list when you start mapping out your next bathroom project. Luckily, many manufacturers have made it easier in recent years for you to answer those questions in a painless, affordable way. |
'We've created several complementing suites of fixtures and faucets,' says Kevin McJoynt from Danze, Inc. 'The elements of each collection were literally made for each other, which makes your job easier.' |
So what should you look for when you're planning your next bath or powder room project? Here are a few things to consider when choosing the key pieces: |
Sink and vanity - Choices are abundant when it comes to the sink area of a bathroom. For those smaller footprint powder rooms, or where storage isn't as critical, consider a pedestal sink. If a pedestal doesn't match your taste or needs, furniture-style vanities can have a significant impact on a room's decor and add e... |
Faucet - This can be one of the most noticeable accessories in the room and one that homeowners and guests interact with the most. Make sure you choose a style and finish that is consistent with the overall decor. A soft brushed nickel or warm oil-rubbed bronze finish can add a distinct detail to the feeling of the roo... |
Toilet - This is one of the best places to go 'green' in your bathroom. High-efficiency toilets use 1.28 gallons per flush (gpf), saving two or more gallons of water during each use compared to many toilets installed in the 1980s and prior. This saves 20 percent compared to more recent 1.6 gpf designs that are standard... |
Shower system - Years ago homeowners had a handful of choices for showerheads. Today, there are hundreds of styles, functions, finishes and components that can comprise a home's shower system. This is a recently discovered area of the bathroom that can really show off your personality and can help you create a unique r... |
Bath accessories - Careful selection of bath accessories is key to creating a finished look to your project. Once again, homeowners have a huge choice. Whether it's the ornate styling of an old-world towel ring, or the sleek lines of a contemporary towel bar, make sure to select accessories that match your room's fauce... |
For more information about the variety and beauty of Danze faucets and fixtures, visit |
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