Shafted
January 5, 2007 12:59 PM Subscribe
I am considering purchasing a shaft-driven bicycle, like this. Does anyone have any experience with such bikes? Maintenance/repair problems? I'm a big burly guy (if that matters) and will be using this bike to ride around to city streets for kicks and grins.
odin... you ever get grease on your leg from a chain? I have. That's an advantage right there.
posted by Doohickie at 1:07 PM on January 5, 2007
posted by Doohickie at 1:07 PM on January 5, 2007
There are two drawbacks to a shaft-driven bike. The main is: you'll only have one gear, which could be a problem in a hilly city.
The second is: it is not as efficient as a chain, and heavier.
I used to take a shift-driven foldable bicycle with me, on my train commute, for only one reason. My clothes wouldn't get dirty if I carried or rode that bike. Still, it never gave me a nice ride, because of the drawbacks mentioned above.
posted by ijsbrand at 1:15 PM on January 5, 2007
The second is: it is not as efficient as a chain, and heavier.
I used to take a shift-driven foldable bicycle with me, on my train commute, for only one reason. My clothes wouldn't get dirty if I carried or rode that bike. Still, it never gave me a nice ride, because of the drawbacks mentioned above.
posted by ijsbrand at 1:15 PM on January 5, 2007
O, I see it is possible to have gears, nowadays. My experience dates from the late 1980s.
Still, it will be hell to change a flat tire for a new one, then, with such a bike.
posted by ijsbrand at 1:21 PM on January 5, 2007
Still, it will be hell to change a flat tire for a new one, then, with such a bike.
posted by ijsbrand at 1:21 PM on January 5, 2007
you'll only have one gear
Small correction - the bicycle linked to has a three-speed internal hub; there are hubs available with up to eight speeds, possibly more.
posted by buxtonbluecat at 1:21 PM on January 5, 2007
Small correction - the bicycle linked to has a three-speed internal hub; there are hubs available with up to eight speeds, possibly more.
posted by buxtonbluecat at 1:21 PM on January 5, 2007
Best answer: Browse, if you want to get a shaft-driven bike because OMG cool! Shaft-driven bike! Then go right ahead. Other than that, it will be less practical and harder/more expensive to service in the long run than a chain-drive bike.
If it's yucky chain stuff you're worried about get something with a chain guard and you're all set.
posted by Mister_A at 1:24 PM on January 5, 2007
If it's yucky chain stuff you're worried about get something with a chain guard and you're all set.
posted by Mister_A at 1:24 PM on January 5, 2007
I wouldn't quite recommend it. Shaft-driven bikes were really conceived for extremely muddy scenarios, and in a city that doesn't compute. For the same amount of money, I'd buy a Redline Monocog (singlespeed) which would be much more durable overall.
posted by tmcw at 2:40 PM on January 5, 2007
posted by tmcw at 2:40 PM on January 5, 2007
Bicycle God Sheldon Brown seems to think they're a bad idea. Heed/ignore his advice at your discretion, but he's never led me wrong.
posted by Opposite George at 3:14 PM on January 5, 2007
posted by Opposite George at 3:14 PM on January 5, 2007
Someone has to be an early adopter, browse!
The only thing I'd worry about would be that the shaft housing seems to also be a part of the bike's frame, and it's all held together by allen bolts. A big burly guy hitting potholes and riding off curbs might rattle this bike apart. But hell, I'm a big burly guy and I've been riding a tiny, 30-year-old Schwinn girl's cruiser bike for two years around city streets, and it's none the worse for wear. Enjoy!
posted by M.C. Lo-Carb! at 3:17 PM on January 5, 2007
The only thing I'd worry about would be that the shaft housing seems to also be a part of the bike's frame, and it's all held together by allen bolts. A big burly guy hitting potholes and riding off curbs might rattle this bike apart. But hell, I'm a big burly guy and I've been riding a tiny, 30-year-old Schwinn girl's cruiser bike for two years around city streets, and it's none the worse for wear. Enjoy!
posted by M.C. Lo-Carb! at 3:17 PM on January 5, 2007
Forget it. The chain is the most efficient, lightest, most easily repairable drivetrain you will find. It fails only in severe mud and severe neglect. You can fix it with a $5 tool and limp home. A new one costs $10. Tools and expertise are ubiquitous if you do not possess them yourself.
Buy yourself a regular bike you can fix with regular tools, then buy a drivetrain enclosure to keep your pants clean. If you still want a gimmick for your bike, buy an airhorn.
posted by Coda at 4:42 PM on January 5, 2007
Buy yourself a regular bike you can fix with regular tools, then buy a drivetrain enclosure to keep your pants clean. If you still want a gimmick for your bike, buy an airhorn.
posted by Coda at 4:42 PM on January 5, 2007
Best answer: The fundamental challenge with a bicycle drivetrain is the awkward combination of high torque but low power that a pedalling human produces.
A 150 lb person standing on the pedals of a bike with standard 175mm crankarms generates almost 90 lbs of torque -- as much as the engine of my 2.0L VW Golf. But, because of the low RPMs, even Lance Armstrong can only sustain about 400 Watts (1/2 horsepower) over an extended period.... please excuse the mishmash of mixed units.
So the drivetrain on a bicycle must be lightweight and efficient to transfer limited power, yet able endure high torque. The problems with shaft-drives are twofold:
1) the shaft itself must be overbuilt to be torsionally rigid
2) the right-angle bevel gears must also be overbuilt to maintain alignment and avoid stripped teeth
Chain-drives don't face any of these problems, which is why they have been used on 99.9999% of bicycles produced since the 19th Century.
If you're just riding for "kicks and grins", you probably won't care that your bike is significantly heavier than a similar chain-driven bike. But I'd worry about the fact that you're "a big burly guy", because the shaft-drive is much less durable under heavy torque.
posted by randomstriker at 4:55 PM on January 5, 2007 [1 favorite]
A 150 lb person standing on the pedals of a bike with standard 175mm crankarms generates almost 90 lbs of torque -- as much as the engine of my 2.0L VW Golf. But, because of the low RPMs, even Lance Armstrong can only sustain about 400 Watts (1/2 horsepower) over an extended period.... please excuse the mishmash of mixed units.
So the drivetrain on a bicycle must be lightweight and efficient to transfer limited power, yet able endure high torque. The problems with shaft-drives are twofold:
1) the shaft itself must be overbuilt to be torsionally rigid
2) the right-angle bevel gears must also be overbuilt to maintain alignment and avoid stripped teeth
Chain-drives don't face any of these problems, which is why they have been used on 99.9999% of bicycles produced since the 19th Century.
If you're just riding for "kicks and grins", you probably won't care that your bike is significantly heavier than a similar chain-driven bike. But I'd worry about the fact that you're "a big burly guy", because the shaft-drive is much less durable under heavy torque.
posted by randomstriker at 4:55 PM on January 5, 2007 [1 favorite]
For extra++ coolness, check out this line of bikes as well (too damn pricy tho...): Biomega.
posted by AwkwardPause at 4:57 PM on January 5, 2007
posted by AwkwardPause at 4:57 PM on January 5, 2007
The other problem with this kind of shaft layout that no one has mentioned yet, is that there are 2 sets of bevel gears involved. The first bevel gear set is near the main crank axle, and serves to change the direction of rotation 90° from the axis of rotation of the crank to the axis of rotation of the shaft. Because of it's small size, this first right angle gear set may even be a lower efficiency worm gear set, rather than a bevel gear, but it is hard to see from the linked photos. Then, there are a second set of bevel gear elements back at the wheel hub, which again change the direction of rotation another 90°.
Overall, this setup could be 5-15% less efficient than a chain, due to sliding friction losses, particularly if the front drive is a worm gear. That's not much real power, perhaps on the order of 10 to 25 watts at your highest crank rate up the steepest hills you'll tackle, but it is power lost to heat that your muscles have to create. A chain drive, properly lubricated and tensioned, will be 99+% efficient.
posted by paulsc at 7:11 PM on January 5, 2007
Overall, this setup could be 5-15% less efficient than a chain, due to sliding friction losses, particularly if the front drive is a worm gear. That's not much real power, perhaps on the order of 10 to 25 watts at your highest crank rate up the steepest hills you'll tackle, but it is power lost to heat that your muscles have to create. A chain drive, properly lubricated and tensioned, will be 99+% efficient.
posted by paulsc at 7:11 PM on January 5, 2007
paulsc, your engineering knowledge is dependable but in this case you don't sound so familiar with bicycle gearing.
I seriously doubt that a worm gear is used in any bicycle shaft-drive, because worm gears involve reduction ratios of anywhere from 10% (10:1) to 1% (100:1). They are used for conversion from high rev & low torque to low rev & high torque. Quite the opposite from what's needed in a bicycle.
Most bicycle gears involve an increase in ratio between 100% and 500%. Even the most aggressive climbing gear in a cross-country mountain-bike still involves only a reduction of about 64% (22T/34T combo).
posted by randomstriker at 12:03 PM on January 6, 2007
I seriously doubt that a worm gear is used in any bicycle shaft-drive, because worm gears involve reduction ratios of anywhere from 10% (10:1) to 1% (100:1). They are used for conversion from high rev & low torque to low rev & high torque. Quite the opposite from what's needed in a bicycle.
Most bicycle gears involve an increase in ratio between 100% and 500%. Even the most aggressive climbing gear in a cross-country mountain-bike still involves only a reduction of about 64% (22T/34T combo).
posted by randomstriker at 12:03 PM on January 6, 2007
This thread is closed to new comments.
posted by Doohickie at 1:06 PM on January 5, 2007