Freewheel vs Casette what exaclty is the difference?

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IIIHorseman
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Freewheel vs Casette what exaclty is the difference?

Post by IIIHorseman » Apr 19, 2012 1:35 pm

I am not sure what exactly the difference is? I assumed that I can just use my existing Shimano cassette on my bike with an upgrade kit. Is this not the case?

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Re: Freewheel vs Casette what exaclty is the difference?

Post by neptronix » Apr 19, 2012 1:53 pm

Nope. you need a threaded freewheel.
Go look at some hub motors on various sites and you'll see the thread on the hubs.. not the familiar cassette style.

China is basically behind the times and uses oldschool tech on the hub motors. Some companies are getting hip to the cassette style ( finally!!! ), but it's a slow trickle.
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Re: Freewheel vs Cassette what exaclty is the difference?

Post by DrkAngel » Apr 19, 2012 7:43 pm

IIIHorseman wrote:I am not sure what exactly the difference is? I assumed that I can just use my existing Shimano cassette on my bike with an upgrade kit. Is this not the case?
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Re: Freewheel vs Casette what exaclty is the difference?

Post by Kingfish » Apr 20, 2012 1:03 pm

Freewheels matured from the original 3-speed by having additional gears and a derailleur. It expanded to 5, then 6, 7, 8, and 9. The problems associated with freewheels are due to the additive cantilever effect 5+ gears has upon the design with breaking or jamming, and by having only 2 bearings for support over then length of the axel. In contrast, Freehubs typically have 3 or 4 integrated bearings and can support axel diameters up to 15 mm which coincidentally makes them attractive for adaptation for hub motors.

There is no way to convert freewheels to freehubs and vise versa for what is probably very deliberate reasons. Shimano used to make some awesome freewheels but production stopped long ago - making good MtB freewheels very scarce. The Chinese knock-offs are fine for a season or two although the quality between units varies; I have a freewheel mounted on my bike now and it clacks loudly as it did on Day-One, yet was able to put 4,000 miles on it. Presently I’m doing an R&R rust treatment on the rear hub motor and purchased a replacement freewheel, same manufacturer, same gearing, and it is much tighter and quieter.

I prefer freehubs, and for a while the ebike mentioned above was configured at a FS-FWD with a giant freehub on the rear. It was so quiet and smooth, and found it very inspiring and full of potential. For a time I took it serious and designed DD replacement that would use FreeHubs as an alternative (before moving on to AF motors), but in truth there is not a lot of room to work with: Freehubs vary quite a bit between manufacturers; the ISO Standard is limited specifically to axel and gear interface, though the rest of the design diverges widely: Just look at Campagnolo and Shimano. I fear that to create a truly integrated freehub DD motor would require licensing and/or partnership with a freehub manufacturer to produce a reliable and field-repairable product. In consideration, I decided to not continue in this pursuit. Eventually I switched out the freehub for a DD freewheel which created the 2WD ebike.

In retrospect, having 9 to 11 gears at this point in my life is pretty silly; during the 2011 road trip only 1 or 2 were used because the 2WD ebike is already powerful and fast. Having a collection of gears is more about insurance I suppose than anything else: A way to recover from total system failure (both drives) by leaving pedaling as the only option forward, in albeit in grandma. :wink:

So the question then becomes rhetorical: Why have gears at all? Because it’s practical for low power-assisted electrically-augmented bikes. Freewheels are fine for up to 7 gears; after that it’s time to consider freehubs where theoretically we can have … what, like 11 gears now? That’s for the roadie. An electric bike with that many gears (on the rear) doesn’t make much sense, and after 8 gears, there isn’t room on most frames to support it.

Anyways, that’s how I picture the differences, mechanically in design and philosophically. :)

ADDENDUM: Sheldon Brown's Freewheel or Cassette?
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Re: Freewheel vs Casette what exaclty is the difference?

Post by amberwolf » Apr 23, 2012 9:47 am

There *are* some hub motors that can use cassettes. I think the Crystalyte G-series can, and the newest Fusin motor can. But naturally, they can't use the thread-on freewheels, as a consequence.


Regarding a lot of gears on an ebike: Unless you A) have a motor/system failure that leaves the bike rideable but unpowered, or B) don't use the motor exclusively but actually do significant pedalling, there isn't a need for anything other than a single-speed freewheel in back anyway.

Since even with multiple gears going very low in gearing, I can't pedal CrazyBIke2 far enough to matter, really, I stopped worrying about it and when I converted my front 9C to a rear, I just used a single-speed freewheel. If I absolutely have to have more than that single speed, I still have the front three rings, even though there is no shifter, so I can manually move the chain down to either of hte two smaller rings there. The problem I have is that the bike is not stable at the very low speeds at which I can actually pedal, or startup pedalling anyway, so I can't both pedal and hold the bike upright until it reaches a suitable speed. It needs little extension wheels like AussieJester's for low-speed riding, that I could retract when I get going. It's on the "someday" list. :lol:

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Freewheel's wobble. Do they fall down?

Post by onemorejoltwarden » Sep 20, 2017 11:20 am

I find the ubiquitous wobble in multispeed freewheels annoying
I assume it stresses the chain.
Is it sloppy machining or the product of aggregated tolerances even in hubs set up correctly?

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Technical Information - Freewheel Wobble
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Re: Freewheel vs Casette what exaclty is the difference?

Post by wturber » Sep 22, 2017 8:52 pm

Kingfish wrote:
So the question then becomes rhetorical: Why have gears at all? Because it’s practical for low power-assisted electrically-augmented bikes. Freewheels are fine for up to 7 gears; after that it’s time to consider freehubs where theoretically we can have … what, like 11 gears now? That’s for the roadie. An electric bike with that many gears (on the rear) doesn’t make much sense, and after 8 gears, there isn’t room on most frames to support it.
Why gears? Yeah. My early experience is that you don't need them much on a hub motor ebike at least. I'm still working out the kinks in my first ebike, but the way I see things working out, I'll probably want/use maybe three gears.

1) Standard very tall cruising gear (20-28mph) with many gear inches 53 x 14, 13, or 12 on a 26 inch wheel.
2) Uphill cruising gear (14-21 mph)for long moderately steep climbs, for when I might want to save extra on battery with a slower pace, and for flat land riding if there's a system failure - 53 x 19 or so.
3) Granny. 42x20 or less. Potential use in case of system failure and hills.

Right now I'm planning on ditching the three ring MTB crank and will be installing a lighter weight road crankset with a 53 tooth chainring and shorter (170mm) crank arms (better for rpms). I appear to have chainstay clearance for the 53T. That leaves me more than three gears, but I doubt I'll use the "extras" very often.
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Re: Freewheel vs Casette what exaclty is the difference?

Post by Ianhill » Sep 22, 2017 11:06 pm

I figured I'd be in high gear most of the time giving my full cranking effort on the 7 speed freewheels last cog that is 11 tooth so the torque being applied to the hub from me is further out from the hub face so there's more force on the freewheel so I will have the famous wobble and carry extra complexity and weight of gears.
So on my a2b meteo I've stripped the derailleur and 7 speed freewheel and stupid lefthanded gripshifter and swapped it to a 16 tooth shimano mx30 1 speed freewheel for 3/32 chain and a bolt on freewheel that only has one rear cog as my swing arm is not horizontal I don't need to use a double cog setup like a normal derailleur, For me it's about making the ride more simple so I've added a mxus 3k to make sure I got good assist power for my single gear that I peddle along efficiently while the motors in its efficient zone to and being a ddd hub there's not a lot that can go wrong to help inspire going a bit further without worrying of a snapped chain from a mid drive etc.

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