Re: Mounting TWO freewheels on one rear wheel hub
by mwkeefer Â» Tue Dec 22, 2009 2:07 am
This is awesome... very cool for those wishing single speed pedal and motorized... I've been looking around at the available thread on freewheels... it seems 13t is the smallest (not quite 11 but it will do - by onyx) and then I see all the other sizes available...
Is there a 3sp blank freewheel that you know of? One which would allow sprockets to be installed and spaced with washers?
Im wondering if it's not possible to use the 9s spacing standard with 3/32" chain to mount 3 sprockets (one on either size of freewheel sprocket for an additional set of speeds... I suppose I could take a 13t, grind down some teeth and then bolt 2 solid sprockets through the remaining teeth (then I would be limited to a 16t for the small side but that could be fixed with larger chainring). Even a 3sp with derailer would be nice.
Any suggestions or ideas?
First, Amberwolf gives very practical advice if you have an older, freewheel-type hub. If you have a newer e.g. "9-speed" freehub, you can buy the cogs and spacers separately. You can buy 9-speed or 8-speed cogs and spacers - it matters if you're going to use indexed shifting. Then just stack 'em up, cog-spacer-cog etc. with the locking ring on top. For that you don't don't need the fancy adapter at all, just get the loose cogs and spacers. One of my 'bents has a mid-drive made from a freehub, with just that kind of setup. You use a standard indexed shifter and limit the derailer throw with the limit screws. Again, this is a single-drive solution, not a multi-freewheeling solution, because the freewheeling is provided by the freehub carrier, to which all the cogs are locked via the splines. In general, the cheapest way to go about this, if you already have the wheel, is just to do surgery on the cassette you already have - pull out the cogs you don't want to use and buy spacers to make up the difference, or stack the unused cogs and their respective spacers at one end and ignore them (by setting your limit screws appropriately). It's actually easier to do all this on a modern freehub - surgery on an old-style freehub is a chore.
Now: if you want one motor gear and multiple pedal gears, and youÃ¢â‚¬â„¢ve got freewheeling at both the motor and crank, you can put a really big cog at the inside (where it would usually be), then spacer-Ã¢â‚¬Å“deadÃ¢â‚¬Â cog-spacer, then the cogs you want to shift. The Ã¢â‚¬Å“deadÃ¢â‚¬Â cog is just a cog youÃ¢â‚¬â„¢re not going to use, because you canÃ¢â‚¬â„¢t put two chains on adjacent cogs. So if you have a stock 9-speed system and you want to run two chains, you can keep 7 shift-able gears. The 7 can be as narrow or wide as you want, within the geometry and chain-handling of your derailer.
Hope this helps,