Multi-speed fixed gear
 

I accept that this may be the dumbest thing that some of you have laid eyes on (though i doubt it considering some of the content on here), but I was just thinking about this...

Say such a thing existed as a fixed hub with a 9-speed cassette on it. Couldn't you theoretically have a multi-speed fixed gear? Does a derailleur need to be used with a freewheel or freehub to work?

I can't say I'd ever want such a device as it'd kind of be the worst of both worlds (no coasting, loss of simplicity of a SS drivetrain), but in theory could this work?

Sturmey Archer has multigeared fixed hubs......................I think

The first time you applied any back pressure on the pedals, you would completely mess up the derailleur and probably have a terrific crash.

I'm really tired so I will let other people talk about internal geared fixed hubs.

I'm acctually planning to build a three speed fixie. It will have a front derailleur and three front chainrings, and a Singleator to pick up the slack chain. I saw one like it on velospace a while back, and have been unable to find it since.

Sturmey archer acctually produced a three speed internally geared fixie, but they do not anymore.

According to sheldon brown, a "Fixed cassette" multi speed fixie wouldn't work because when you backpedal, the derailleur arm will simply bend back.

Somewhere on the net there are instructions to make a two speed fixie from a three speed hub, but apparently it is very difficult to do this.

When I was at UBI, there was this dude who had a rear hub that was an internal 5 speed hub converted to a 3-speed fixed gear. He had a grip shifter mounted on the end of his bullhorn bars. It was crazy. The owner of the bike did not do the conversion himself so I have no idea how it was done.

The 9 speed cassette thing wouldn't work though because different sized cogs need different chain lengths, thus needing a derailler to take up the slack.

Think about it. As soon as you stop pedaling, or even soft pedal a little, the rear gear is going to start throwing chain at the front, and pretty soon the RD is going to get pulled straight, introducing slack up top, and the whole thing is going to foul. If you don't believe me, go ride an old schwinn with a shimano FF setup with a fodangled front freewheel.

There are multispeed fixed hubs, both an old S-A model that there have been rumors of reviving and then various mods to existing internal gear hubs. Search on here or google and you'll find a ton about them.

I remember seeing that too, I think on here or FGG as I never look at velospace. I think it was a 2 speed, I wouldn't think you could get enough teeth difference to make a 3 speed worth it.

I would expect this to ride really weird, even in the largest gear you're going to need to have a ton of slack or it won't shift, then in the lower gears it's going to be so much slack it won't even feel like fixed unless you try to stop pedaling for like a quarter rotation.

"You cannot use a derailer on a fixed gear bike, even as a chain tensioner, because when you resist the rotation of the pedals, you would bend the derailer." Sheldon Brown

Right...I figured there was a catch. That was just my "it's been a long day" sort of wandering thought that I didn't think through too well.

But as has been mentioned, there is an ultra rare, and VERY expensive, vintage Sturmey Archer fixed 3 speed hub. And there've been moves here previously to hassle SA into reissuing it, or creating a new one.

A vintage SA three speed fixed and a regular SA track hub sold together on ebay for 900 bucks recently. You can probably still find the ended auction but I'm way to tired to search for it.

Surly and possibly others sell a Dingle, a dual cog that would give you two manually shifted gears. You can combine it with matching chainrings up front so when you change cogs you also change chainrings, thereby keeping a perfectly straight chainline. Just shifting the cogs would still leave the chainline in good shape, though.

Rivendell's Quickbeam does this, in effect giving you four gears. You need slanted dropouts for this or you'll have to adjust your rear brake, assuming you have one.

surly specifies very clearly that you cannot use the singleator with anything other than a freewheel. sounds like a good way to destroy it.

Ira Ryan built up a two-cog, two-chainring fixed touring bike, designed so that he can be in either small cog/large ring, or large cog/small ring I think. Looks like the dropouts are slanted.

Take a look:
http://farm2.static.flickr.com/1355/...d621f91c_b.jpg

Check this one:
http://www.sheldonbrown.com/asc.html