Alt Bike Culture - Existing gearing methods
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I'm doing a project to come up with an alternative design to the derailleur method of changing gears. I was just wondering if anyone could tell me where I could find some info on whatever other methods are currently available or in development stages. Stuff like any CVT designs used on bikes or any experimental designs
Geared hubs are another option. I'm not aware of any CVT system that would be light enough to be viable.
10-05-05, 05:45 PM
check petespeed (http://www.petespeed.com/) for a really simples gearbox sistem, and the G-Boxx site (http://www.g-boxx.org/_2-english/history/_1-history.html) for some addicional ideas in temrs of gearboxes, most of this can be modified to use belts, but chains still more efficient..
also check Nicolai (http://www.nicolai.net/) since they are at the fore front of development (the first 3 bikes on the top have gearboxes running out of their bottom bracket.
Here is a small photo gallary (http://patineto.smugmug.com/gallery/840772) gatter about diferent alternatives
and here are some examples like the petespeed tranny.
a planetary gear box with 14 steps
http://patineto.smugmug.com/photos/35411760-M.jpg made by Rolloff in germany.
and here is a gallery with NIcolai bikes (http://patineto.smugmug.com/gallery/719033/3/38310183) were if you pay attencion you can see there evolution and a sample of them, please don't start with the "Why the cost so much" crap...they do but someday they will be a lot cheaper
Hope this helps...Oh Honda is making their own gearbox and is suppose to work like a CVT but nobody really know so far..that will be great if can be made efficient, bulletproff and cheap.
10-05-05, 07:01 PM
Another possibility, this one from a cyclist as well: http://www.andersoncvt.com/
I'm an unabashed believer that CVT is coming to bicycles.
Supposedly Audi has greatly improved the efficiency of the automobile CVT by putting some kind of metal chain inside the rubber transmission belt. I have no idea whether a smaller, lighter, version of that will ever be viable for bicycles but it sounds like it might.
Personally, I think that conventional derailleur systems could be improved a lot. One of the ways a person might do this is to eliminate some of the duplication of gear ratios (large-chainring, large-cog giving same ratio as small-chainring+small-cog). Another improvement for those of us that commute in bad weather would be to cover the gears up so they don't get snow/rain/road grime on them.
10-10-05, 11:54 PM
I was wondering if you could substitute a hub gear for a gear box. You'd need to weld it in a cage and blot it to the frame, weld a larger sprocket to the non-drive side to the outer part of the hub, but you'd have a sealed, internal gearbox. Run a 3 speed front to a 7 speed rear with just the right spaceing... Seems ridiculous unless you look at the drastic steps taken to expand the gearing of road bikes to the Ultegra 10 speed rear freehubs and triple fronts, that still overlap terribly. Drag smag. Give me a system with continuous little steps from hauling groceries uphill to flying down a Colorado pass and never, ever having a skipped chain... or a frozen derailer, or having to clean and oil every night... or replacing the cog twice a year or better and a chain every few months and bent teeth on super light chainrings...
Just a thought.
10-11-05, 04:12 AM
You say "drag smag" now but every new hub gear that isn't just perfect has reviewers complaining that it's like riding in treacle. Drag matters, unless it's on a wackybike.
Anyway, your system exists, it's the Rohloff. 14 evenly-spaced gears.
10-11-05, 12:49 PM
Yeah, i'll agree riding in drag can be tough, those boots really chafe... oh wait, can i erase that part...
I'm just saying that compared to my old Nishiki 8 speed where the gears were big chunks of metal and the money and research that went into turning that into today's Carbon Dura Ace has made a huge difference. If you made a Carbon Fiber Dura Ace hub gear i'd bet you'd start getting closer to the efficiency.
And if you look at the average drivetrain for a city bike, i'll bet alot of advantage is lost due to gunky drivetrains or the occasional skipping gear.
but only 14 gears, awww i need at least 30 to feel manly!
Other question i had is what happened to hub brakes? I know they're still out there but with everyone cutting both weight and wind surface and modern brakes still mostly sucking, i figured a light hub driven brake would make a comeback.
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