Shimano FF front freewheel

turnofftheradio

turnofftheradio

Member
I have a couple of old schwinn suburbans (76 womens 78 mens). Both have the shimano FF system, the womens is also positron. It's been quite a while since I serviced them, they are difficult to service, but I can. As I remember they were well built, but maybe not up to motorized bicycle standards.

Anyone jack shafted one of these shimano FF? I have a 49cc china that would fit it well, and they all gather dust a few feet away from each other.
The mens was my dads, a 10 speed and requires his legs to straddle the bar, mine are too short, but I still ride it once a year. The Womens was moms and has a 5 speed positron. Its in great riding condition still, and has an absolute ton of miles.
 
I have one of those, it's fitted to a New Zealand made Healing woman's 10 speed with a Mixte frame. It's been years since I rode a bike fitted with the FF system though, - the bike I now have was thrown out for scrap and needs a lot doing to it before it's serviceable again.

All those years ago I was impressed with how the FF system worked and now I have this old bike I too have wondered if it's possible to use it with a motor. It's possible to fit a China Girl into a Mixte frame, but the clearances are very close. I had already started in on such a conversion on another Mixte bike before I found the FF Healing and now I'm not sure if I should begin again on the FF system frame (sigh).

.blady
 
Nice to hear somebody else enjoyed the system too. They make such a nice sound in freewheel, unlike any other bike I've ridden. The womens with the positron and ff was really neat coasting and clicking as it shifts. It wasn't until recently I found people are not very fond of the positron, but I think its great.

In interesting fact, the rear sprockets have dogs and springs. If your chain was to become jammed the rear wheel could freewheel without the chain moving, but there is considerable resistance to do this. When assembled the gears are very tight against each other. each rear gear can turn independently. If you are nuts enough to take the rear apart, be very careful those dogs and springs are very small and can take flight, If i remember each gear has 3 dogs/springs. it is tricky to stack them without getting frustrated.

If I cant motorize this, they are still not going anywhere. I have too many memories on them.
 
I had a bike a looong time ago with that setup. when i got into motorizing stuff i thought about using one for a jackshaft, but never did.

When i was looking into it i think you need to use the rear hub that came with it in case the freewheel jams. like you said, it's got a safety mechanism built in. otherwise your pedals would suddenly start moving if the freewheel seized, and at 30+mph you'd probabl get launched into space.

Which is no fun. trust me. i know...:)

If i ever score one of those bikes again, i'll probably figure it out...
 
Could you not simply use a standard freewheel rim? The gear spacing is the same.
I too thought about jackshafting one of thes.... at least until I got offered ten times what I paid for it!
SOLD!
 
maniac57 said:
Could you not simply use a standard freewheel rim? The gear spacing is the same.
I too thought about jackshafting one of thes.... at least until I got offered ten times what I paid for it!
SOLD!
Click to expand...

I think that you could but it would be confused where to freewheel, and probably cancel the ability to shift during coast, or at least make it erratic.

That does make me wonder however, if there is enough force to start an engine from the chain without that rear gear slipping. I bet not, and these cranks are not easy to widen for a pullstart...

going to have to think more about this one.
 
turnofftheradio said:
I think that you could but it would be confused where to freewheel, and probably cancel the ability to shift during coast, or at least make it erratic.

That does make me wonder however, if there is enough force to start an engine from the chain without that rear gear slipping. I bet not, and these cranks are not easy to widen for a pullstart...

going to have to think more about this one.
Click to expand...

Ok, I thought...

It would be easy to just tack weld ONE gear in the rear as a start gear, maybe the big one makes most sense, since at speed, I'd never be running in it.
 
turnofftheradio said:
Ok, I thought...

It would be easy to just tack weld ONE gear in the rear as a start gear, maybe the big one makes most sense, since at speed, I'd never be running in it.
Click to expand...

The engine will take care of the shifting. Since the engine will keep the front freewheel spinning, there should be no difference between the two when motorized.
Only while riding normally would the rear freewheel cause any shifting issues.
It would still start like any other shift-kit motorbike. You have to keep pedaling while starting.
 
maniac57 said:
The engine will take care of the shifting. Since the engine will keep the front freewheel spinning, there should be no difference between the two when motorized.
Only while riding normally would the rear freewheel cause any shifting issues.
It would still start like any other shift-kit motorbike. You have to keep pedaling while starting.
Click to expand...

Doh, I overthought It :)
thanks for bringing me back to reality
 
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