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Old 06-27-09, 11:48 PM   #1
77Univega
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Combine front derailleur with Sturmey Archer

Has anyone had success with adding a front derailleur onto a 3-speed bicycle with a rear in-hub shifter (like a Sturmey Archer) thus creating a transmission with six usable gears?
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Old 06-27-09, 11:56 PM   #2
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You would need a chain tensioner to be able to run a multicog front and a singlecog back.
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Old 06-28-09, 07:30 AM   #3
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I'm not sure what all would be required up front. Are the bottom bearing brackets the same for each style of crank? Is it a problem to mount a front derailleur on a bike that wasn't made for it? Seems like it would be easier to just get a 7-speed hub.
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Old 06-28-09, 11:24 AM   #4
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Quote:
Originally Posted by 77Univega View Post
Has anyone had success with adding a front derailleur onto a 3-speed bicycle with a rear in-hub shifter (like a Sturmey Archer) thus creating a transmission with six usable gears?
I'm pretty sure that someone has tried just about anything you could think up. Bicycles do lend themselves to the fun of mechanical experimentation. If someone bothers to put a chain tensioner on back, the next logical step would be to add some cogs for it to shift.



The 1/8th inch chain three cog 15-19-23 was made to yield five useable gears with next to nothing gained by double shifting, because all of the interior ratios are basically duplicated.

You get ratios of:

39-46-63-84-107

If you regard the three speed hub ratios as if they were a triple front, it would be like having 35T-46T-62T chainrings.

For example, with a five speed freewheel 14-16-19-22-26 without double shifting you get 7 gears:

35-46-54-63-75-85-115


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Old 06-28-09, 07:54 PM   #5
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+1 on you can try bout anything with the mechanics of a bike and not fall flat...fall maybe but learn too. I have a short wheel base bent that I made and put a second derailer in the middle to get some lower gears and make a "mountainclimer' out of it.. as has been stated I got some overlay of gears but it still works. So I say if you have the time and materials and want to experiment, go for it.
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