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  1. #1
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    New Shaft drive folder

    http://tinyurl.com/5mnbt7

    Most of the other 99 shots in the set are worth viewing too.

  2. #2
    ...poet... timo888's Avatar
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    I like the one that looks as though it had been designed by the person who built the Orgasmatron for Woody Allen's Sleeper.

    Regards
    T

  3. #3
    hubgears BB49's Avatar
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    You can get a simiiar bike now from Dynamic, with an actual weight of 31 lbs.

    I checked the beixo website. The specs look honest, hope that becomes a trend.

    They both have a kickstand attached at the rear axle, unlikely to work if you have even a mild breeze.
    Last edited by BB49; 09-09-08 at 04:43 PM.

  4. #4
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    Shaft drives always look like a great idea. Unfortunately, they are not nearly as efficient as the standard dirty old obnoxious antique chain drive.

  5. #5
    ...poet... timo888's Avatar
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    Quote Originally Posted by werewolf View Post
    Shaft drives always look like a great idea. Unfortunately, they are not nearly as efficient as the standard dirty old obnoxious antique chain drive.
    You might not want one on a Pashley Moulton, but for a commuter bike or an XC/rough-terrain bike, a shaft drive has merit. No chain to jump the sprocket on bumpy surface. Less chance that oil will get on your clothes or on someone else's clothes when you bring your folder onto the train or into the elevator.

    Regards
    T

  6. #6
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    I found this site looking for folding bike manufacturers. They have a cool 3d view of the shaft inside and out.

    http://www.dynamicbicycles.com/

  7. #7
    ...poet... timo888's Avatar
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    Quote Originally Posted by noob_island View Post
    I found this site looking for folding bike manufacturers. They have a cool 3d view of the shaft inside and out.

    http://www.dynamicbicycles.com/
    Thanks for the link. The site is clear and concise, and that animation was well done.

    Regards
    T

  8. #8
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    From the Q&A:

    "How durable is the shaft drive?
    Our shaft drive is designed to have twice the life expectancy of a chain under comparable riding conditions. Our shaft drive is made of the highest grade components..."


    Well, chains only have a limited life, and then you can replace them, and the cogs too, if necessary...but when the shaft and its cogs degrade, that's the end of the bike.

    The shaft drive is a great concept, but with too many practical problems.

    Sheldon Brown on the shaft drive:


    Shaft drive

    An alternative drive system, replacing the chain and sprockets with right-angle bevel gears and a shaft running inside the right hand "chainstay." Shaft drive was briefly popular around 1900, and occasional attempts are made to revive the design. Unfortunately, shaft drive turns out to have more problems than advantages.
    A shaft drive requres heavier frame construction around the bevel gears to maintain their precise alignment under load. The drive system is heavier and less efficient than a good chain drive.
    For reasons of clearance, the bevel gears of a shaft drive bicycle must be considerably smaller than the typical sprockets used with a chain drive. The smaller size of the gears causes an increase in the stresses on the whole support system for the shaft. This problem is exacerbated by the fact that the stresses from the shaft drive are not well resisted by the triangulated structure of a bicycle frame, because the stresses are perpendicular to the triangle.
    Most of the advantages touted by proponents of shaft drive are only advantages compared with open-chain, derailer gear systems. Many proponents of shaft drive use specious (if not dishonest) arguments "comparing" shaft drive systems with derailer gear systems. Any such comparisons are meaningless, it's like comparing apples and locomotives.
    A valid comparison of shaft vs. chain drives can only be made if both bikes use the same type of gearing, whether singles-speed or with an internal gear system.
    These same advantages can be obtained with chain drive using a fully-enclosing chain case, as with old English roadsters and many current Dutch bikes.
    Shaft drive proponents also often compare sealed, enclosed shaft drive systems with open, exposed chain drive systems. This is also a misleading comparison. All of the advantages claimed for shaft drive can be realized by the use of a chain case.

    http://www.sheldonbrown.com/gloss_sa-o.html#shaft

  9. #9
    ...poet... timo888's Avatar
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    Quote Originally Posted by werewolf View Post
    ... when the shaft and its cogs degrade, that's the end of the bike.
    I don't know, but find this very hard to believe. You're saying the shaft, though it's being described as a consumable item, is irreplaceable?

    Quote Originally Posted by werewolf View Post
    Sheldon Brown on the shaft drive:

    ... A shaft drive requres heavier frame construction around the bevel gears to maintain their precise alignment under load. The drive system is heavier and less efficient than a good chain drive.

    How much heavier? How much less efficient? From what I have read, it's not so much heavier and so much less efficient to justify throwing the baby out with the bathwater.


    For reasons of clearance, the bevel gears of a shaft drive bicycle must be considerably smaller than the typical sprockets used with a chain drive. The smaller size of the gears causes an increase in the stresses on the whole support system for the shaft. This problem is exacerbated by the fact that the stresses from the shaft drive are not well resisted by the triangulated structure of a bicycle frame, because the stresses are perpendicular to the triangle.


    Warrants further investigation. Is the direction of stress causing cracked frames or shimmy?


    Shaft drive proponents also often compare sealed, enclosed shaft drive systems with open, exposed chain drive systems. This is also a misleading comparison. All of the advantages claimed for shaft drive can be realized by the use of a chain case.

    In addition to the greater cleanliness, there's also the fact that there's no chain to jump of the sprocket. Do the fully-enclosed chains offer that feature too? I don't know.

    Regards
    T

  10. #10
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    "I don't know, but find this very hard to believe. You're saying the shaft, though it's being described as a consumable item, is irreplaceable?"

    In practical terms, yes, irreplaceable.

    Hey, I love the concept of the shaft drive. I'd love to see something that could replace the dirty, heavy, annoying antique chain drive, but I'm afraid this ain't it.

  11. #11
    ...poet... timo888's Avatar
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    Quote Originally Posted by werewolf View Post
    "I don't know, but find this very hard to believe. You're saying the shaft, though it's being described as a consumable item, is irreplaceable?"

    In practical terms, yes, irreplaceable.

    Hey, I love the concept of the shaft drive. I'd love to see something that could replace the dirty, heavy, annoying antique chain drive, but I'm afraid this ain't it.
    By "in practical terms" do you mean it's labor-intensive and costly to replace the shaft?

    Regards
    T

  12. #12
    ...poet... timo888's Avatar
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    Here's a review of one:

    http://www.bikecommuters.com/2007/07...drive-bicycle/


    Says it adds one pound and costs $89 to replace the shaft (after 6000-10000 miles).
    Regards
    T
    Last edited by timo888; 09-13-08 at 10:04 AM.

  13. #13
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    I just read the review you linked to, Timo.

    "Does the shaft-drive wear out? Well, yes…eventually. Patrick Perugini, the president of Dynamic, indicated that the shaft-drive is rated for 6000 to 10000 miles (depending on frequency of greasing) before it requires replacement. And, a replacement assembly with all bearings is only $89.00, available directly from Dynamic."

    Assuming the unlikely event that Dynamic will still be in business and still selling the exact part for $89 when you need it.

    The shaft and cogs are easily owner replaceable then - like held on by bolts?

    The bike itself seems to be rather sloppily built up with cheap components and its geometry is too upright, for me anyway.

    Linked via one of the comments under the review - Trek's new belt drive. This is more interesting to me.

    http://www.trekbikes.com/us/en/bikes/urban/soho/soho/

  14. #14
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    Also, one comment referred to a broken shaft, another to the necessity for frequent greasing.

  15. #15
    ...poet... timo888's Avatar
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    I agree with you that one should weigh the company's staying power if contemplating a purchase of one of their bikes. But it's a distortion to say you have to throw the bike away if the shaft breaks or wears out.

    Regards
    T

  16. #16
    ♋ ☮♂ ☭ ☯ -=(8)=-'s Avatar
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    Here's from someone who owns one.......
    The shaft will never wear out if its greased. Its sooooo overbuilt.
    I cant see it ever needing to be replaced, despite what the guy at Dynamic
    sez. Show me someone with 10K on one to disagree and Ill believe otherwise.
    The problem I have is with the bottom bracket that is underbuilt. That is
    the weak link on my Dynamic/Newport. It requires constant tightening of
    all of its three, whoppingly huge, 2.5 mm screws. There should be at least
    two more and of a larger diameter. If you've ever had your new bike sand blasted
    on the coast of Florida, or tried to ride year 'round in Vermont and want gears
    or need to carry your bike up a flight of stairs and not enjoy grease on your clothes,
    you will understand why some people like them. If you want to make time with
    the local Carbon Fibre, Power Ranger clubbies, it isnt the bike for you

  17. #17
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    "It requires constant tightening of
    all of its three, whoppingly huge, 2.5 mm screws"


    Have you tried Loctite?

  18. #18
    hubgears BB49's Avatar
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    I have owned a shaft drive with a Nexus hubgear. Now I have a chain with the Nexus hubgear. Both 20" folders, very close in weight and gearing.
    The chain by itself is fairly low maintenance. Mine is clean because I use no grease.
    Grease will not speed you up, it makes the chain quieter and last longer.
    I like my setup the best, just my preference.

    The geardrive is the lowest maintenance and clean. A chain is more efficient, by a little bit, when very clean. With a deraillier you need to be in gear combo with a fairly straight chainline to be more efficient. If you add a full sealed chaincase, a chaindrive will be heavier.

    Major Taylor won his races using a shaftdrive. Now you will win races with a chain. Outside of a timed race, you will not notice the average 2% difference
    Last edited by BB49; 09-15-08 at 03:33 PM.

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