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FFS - front freewheel system
I am rebuilding an old panasonic road bike I found, and it is equipped with
shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? Thanks guys! Adam |
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#2
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FFS - front freewheel system
"Jacobe Hazzard" wrote in message ble.rogers.com... I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? Thanks guys! Adam According to Sheldon Brown's web-site: FFS ® Front Freewheel System. The freewheel was built into the bottom bracket, so that the chain would turn even when the rider was coasting. This was to allow shifting while coasting--a solution in search of a problem. Apparently it wasn't terribly popular and didn't last long. I don't know anything about it other than what I found doing a quick goodle search. Maybe ol' Sheldon will drop by................ |
#3
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FFS - front freewheel system
Jacobe Hazzard wrote:
I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? Beginner cyclists don't always realize that you need to be pedaling to shift a derailer. This was especially true of folks who started out on internal-gear 3-speeds. When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. See: http://sheldonbrown.com/shimano1982/pages/35.html Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? It's attached to the bottom bracket spindle. This precluded use of a standard square taper BB for clearance reasons, so they use an early "Octalink" splined setup that turned out to be rather unsatisfactory. There was also a variant that used a one-piece crank, fitting into a standard American-type bottom bracket shell. I used these to make coastable kidback tandem cranks when my kids were little. Sheldon "An Idea Whose Time Has Gone" Brown +------------------------------------------------+ | What was the real cause of the 1861-65 war? | | http://sheldonbrown.net/slaverywar.html | +------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#4
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FFS - front freewheel system
In article . rogers.com,
Jacobe Hazzard wrote: This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? The idea was that the chain keeps moving, so that you can shift when you coast, in case you find shifting while you pedal too difficult. Somebody must have thought it was a good one, at some point... -- --- "I never had to pretend I felt the lyrics. I could always relate to the words." --Teddy Pendergrass |
#5
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FFS - front freewheel system
"Jacobe Hazzard" wrote in message able.rogers.com...
I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? Thanks guys! Adam Dear Adam, A friend's father bought a bike equipped with this odd system when I was in high school. We all marvelled at the strange way that the chain kept moving, but none of us had any idea of the purpose. Apparently, they were sold without dealers having a clear notion, either. Thanks for raising a long-forgotten question and getting the others here to provide the answer. Carl Fogel |
#6
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FFS - front freewheel system
Carl Fogel wrote:
"Jacobe Hazzard" wrote in message able.rogers.com... I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? Thanks guys! Adam Dear Adam, A friend's father bought a bike equipped with this odd system when I was in high school. We all marvelled at the strange way that the chain kept moving, but none of us had any idea of the purpose. Apparently, they were sold without dealers having a clear notion, either. Thanks for raising a long-forgotten question and getting the others here to provide the answer. Carl Fogel Not a longforgotten question since you can mount Powercranks with fixie rear with similar results Several electric bikes, including a couple of my Currie's, use a lef side electric chain drive with the freewheel attached to motor side o the chain drive. Unfortunately, another problem with thes implementations are that you are still turning the second chain eve when not running the electric drive so you are introducing extr frictional losses-about 1%. The analagous situation would exist on th FFS or Powercranks-fixie combinations during coasting Christini and Spicer AWD mountainbikes probably have similar issues wit the front drive - |
#7
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FFS - front freewheel system
Carl Fogel wrote:
"Jacobe Hazzard" wrote in message able.rogers.com... I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? ----8---cutting Dear Adam, A friend's father bought a bike equipped with this odd system when I was in high school. We all marvelled at the strange way that the chain kept moving, but none of us had any idea of the purpose. Apparently, they were sold without dealers having a clear notion, either. Thanks for raising a long-forgotten question and getting the others here to provide the answer. I heard about this one years ago. The only advantage I could see with this system is that it allows the rider to shift gears while coasting, i.e. without turning the pedals. Now why on earth someone would . . . aw, forget it . . . ROTFL . . . /Robert |
#8
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FFS - front freewheel system
Jacobe Hazzard wrote:
I am rebuilding an old panasonic road bike I found, and it is equipped with shimano FFS, that's where the BB spindle freewheels. This is bizarre, the chain moves when I'm coasting! What's the purpose of such a system? When I found the bike it had a 5 speed freewheel on the rear wheel, and the wheel + derailer look pretty old, not like they were added on late in the life of the bike, so that makes the FFS pretty useless. Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? Thanks guys! Adam A few years ago, the "auto bike"made use of this concept. It used a speed rear cassette and there were weights on the wheel which move toward the outer part of the wheel by centrifugal force as the speed o the bike increased. These weights were linked to the derrailuer so tha as the speed increased, and the weights moved out, the chai automatically moved to a smaller cog. The reverse happened as the bik slowed down. The freewheeling chainwheel was necessary so the shift would happen even if the rider was not pedalling. I don't know whateve became of the Autobike. It occurs to me it might be useful on a tande for those who prefer indepedent pedallin - |
#9
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FFS - front freewheel system
Sheldon Brown wrote in message ...
Also, where is the front freewheel exactly? Is the BB shell the standard size, or is there something special about it? It's attached to the bottom bracket spindle. This precluded use of a standard square taper BB for clearance reasons, so they use an early "Octalink" splined setup that turned out to be rather unsatisfactory. There was also a variant that used a one-piece crank, fitting into a standard American-type bottom bracket shell. I used these to make coastable kidback tandem cranks when my kids were little. To answer a question Sheldon missed: the BB shell on your Panasonic should be a standard 68mm width English thread unit. IIRC, once you get the arms off the spindle, the left cone unscrews from the spindle and the bearings fall on the floor. After removing the spindle to the right (and dropping more bearings), you'll see that the cups threaded in the frame have internal splines. I *think* the tool that fits these splines is the standard Shimano freewheel removal tool. A note: the rear cogset had a limited freewheel action built into it. If something jammed the chain, this would allow the rear wheel to continue to turn. It felt like a conventional freewheel with *really* tight bearings. Jeff |
#10
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FFS - front freewheel system
Dan Burkhart wrote:
A few years ago, the "auto bike"made use of this concept. It used a 5 speed rear cassette and there were weights on the wheel which moved toward the outer part of the wheel by centrifugal force as the speed of the bike increased. These weights were linked to the derrailuer so that as the speed increased, and the weights moved out, the chain automatically moved to a smaller cog. The reverse happened as the bike slowed down. The freewheeling chainwheel was necessary so the shifts would happen even if the rider was not pedalling. I don't know whatever became of the Autobike. It occurs to me it might be useful on a tandem for those who prefer indepedent pedalling Autobike was selling by infomercial last year There website is still operational: http://www.bpc.co.kr - |
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