Build a wheel hub with freewheel gears on both sides?

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skyl4rk

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Bicycle mechanics please help:

Is it possible to build a wheel hub with freewheel gears/sprockets on both sides using readily available parts?

Ideally the gears would be 44t on the left and 15t on the right, and both would freewheel when coasting.

I have heard of a hub called a fixed gear flip flop hub, which has a freewheel on one side and a fixed gear on the other. Maybe one of these hubs could be built with a freewheel gear on each side, both freewheeling in the same direction?
 

ocscully

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Joined
Jun 23, 2007
Messages
659
Bicycle mechanics please help:

Is it possible to build a wheel hub with freewheel gears/sprockets on both sides using readily available parts?

Ideally the gears would be 44t on the left and 15t on the right, and both would freewheel when coasting.

I have heard of a hub called a fixed gear flip flop hub, which has a freewheel on one side and a fixed gear on the other. Maybe one of these hubs could be built with a freewheel gear on each side, both freewheeling in the same direction?

Unfortunately the flip flop type of hub will not work since both sets of threads are right hand threads. To accomplish what you are asking you need a hub with left hand threads on the left side. Staton-Inc makes such a hub as does GRUBEE Then the problem becomes getting the 44t you want for the left side. The left hand thread SS freewheel that Staton offers is an 18t. You might be able to custom mount the 44t to the 18t freewheel. The Grubee Hub comes with a lefthand threaded freewheel with a universal mounting flange rather than a sprocket and you mount what ever sprocket you want to it.

ocscully
 

lennyharp

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Joined
Apr 17, 2008
Messages
216
David Staton offers a special hub with a special freewheel as part of his motor gearbox assembly. You get some well machined and designed parts from David. I am thinking of getting my second kit from him. He does sell just the parts so you can go that way if you already have most of what you need.
 
Joined
Dec 7, 2009
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yeah it will work if you flip flop your engines drive shaft direction to the desired freewheel movement to get forward rotation flip flop the engine this will be easiest on a rear carrier setup
 

happycheapskate

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Nov 5, 2009
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1,390
If the 44t/xx size cog on the left freewheels, you will need a pull start and locking clutch lever or centrifugal clutch on your engine. You will not be able to pedal start it.

I believe this product is what you are looking for.
Consult the seller before buying. I believe it has a left side 36t freewheel, and takes a standard BMX freewheel cog on the right. I could be wrong though, so contact the seller.


http://cgi.ebay.com/bicycle-Motoriz...Cycling_Parts_Accessories?hash=item2c526240ec
 
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happycheapskate

Active Member
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Nov 5, 2009
Messages
1,390
Thanks for the idea. I will use this product in the next MB build if use pull start

Good question though: I would like to use this product if I built a bike with a rope start. Then I could pedal the bicycle normally with the engine off.
Keep in mind you can thread a 6speed freewheel onto a bmx hub, but you might have to expand your frame to fit and still clear the 36t left cog and chain to avoid sawing off your chainstay.
A nice alternative would be to simply use a BMX freewheel in the back and a 22/32/42 front chainring, with the rear derailleur on only to take up slack. (use a bicycle spoke or coat hanger to make a "cable" substitute, to hold the derailleur in place on the only rear gear.) 3 speeds ought to be enough if you have a motor. I've used a 3 speed bicycle like that before (It had a 28/38/48 c201 crankset) . It was a nice townie bike. I'm currently using a MB with a one speed pedal side, and its enough to start bike and take off from stop lights under human power, or ride up to the office buildings.

PS they are "rare" but there are 2 speed RH thread bmx freewheels, http://cgi.ebay.com/WHITE-INDUSTRIE...emZ370311569544QQcategoryZ42328QQcmdZViewItem
And you may be able to find an ACS or similar for much much less.
 
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