Two-Speed Sheldon-Inspiration

Dreaming about a two speed bike...

single speed rear, say 18t

two rings on the front, something like 52 & 40.

I was thinking of using a fixed-position derailleur (i.e. no cable, no lateral movement, just as a tensioner) on the back to guide it, I assume a singulator wouldn't work as it doesn't have a cage-y thing.

Obviously 3 3/2" -ville.

Might put theives off the scent if they see a bike with gears ;)

Can anyone tell me why this wouldn't work, or have tried something similar? (the bike, not the thief bit, they'll take anything)

And even could it be done fixed?! Or is that a silly question if there's a derailleur?

Any help or abuse recieved thankfully. Just not the tumbleweed pleeease

if you are gonna use a rear derailleur for tension anyway - you might as well have the gears on the back rather than the front? unless this won't work with your hubs - in which case go for it!

Can't use a derailleur or other tensioner with fixed, but you can use a surly dinglespeed cog.

It's a double fixed cog with tooth counts two apart (eg 17 and 19). Then you can run two chainrings up front that are also two teeth apart (eg 42 and 40) to get two different gears (eg 42x17 and 40x19) using exactly the same chain length. You can also get a two speed eno freewheel or use a cassette hub and acouple of on-one sprockets if you wanna do the same SS.

provenrad if you are gonna use a rear derailleur for tension anyway - you might as well have the gears on the back rather than the front? unless this won't work with your hubs - in which case go for it!

Bloody good point, two mechs and only one working does seem a bit dumb. But i like the idea of a non-dished or (only slightly dished, if single sided) wheel.

Momentum Can't use a derailleur or other tensioner with fixed, but you can use a surly dinglespeed cog.

It's a double fixed cog with tooth counts two apart (eg 17 and 19). Then you can run two chainrings up front that are also two teeth apart (eg 42 and 40) to get two different gears (eg 42x17 and 40x19) using exactly the same chain length. You can also get a two speed eno freewheel or use a cassette hub and acouple of on-one sprockets if you wanna do the same SS.

Feck! Great info thanks Mom(entum).
I like the sound of the surly dinglespeedy thing, quite fancy that...

All food for thought.

I THINK, one major gear manufacturer is doing a 2 speed planitary crank and chainring combo next year, could be the perfect (expensive) answer. 2 speed front with one chainring!!!

That's o(k).

I think Briston Cycles might have some of the dingle cogs or could order them. Here's a picture

BillB I THINK, one major gear manufacturer is doing a 2 speed planitary crank and chainring combo next year, could be the perfect (expensive) answer. 2 speed front with one chainring!!!

CONFUSED

Momentum That's o(k).

I think Briston Cycles might have some of the dingle cogs or could order them. Here's a picture

wow, sexy looking bit of kit...

Momentum That's o(k).

I think Briston Cycles might have some of the dingle cogs or could order them. Here's a picture

How do you actually change gear when using this, is it a manual change of shifting the chain front and back? I can't see how you could use a mech...

dingle cog requires you to move the chain manually with greasy fingers.

the thing I was talking about is like a 3 speed hub, but with 2 speeds and part of the front chainring, not the hub!!

what about using a Schlumpf 2-speed bottom bracket - it woudl work fixed woudln't it?

http://www.schlumpf.ch/antriebe_engl.htm

But what's the point? If you need gears get 20 of them - or maybe a Sturmey Archer hub...

lukerative what about using a Schlumpf 2-speed bottom bracket - it woudl work fixed woudln't it?

http://www.schlumpf.ch/antriebe_engl.htm

Hmmm, that is kinda what I was talking about, I think sram may be bringing a version out though.

Platini But what's the point? If you need gears get 20 of them - or maybe a Sturmey Archer hub...

yep good point.

Still want a front shifter and no back, I want The Next big Thing (it'll have to be done on a shopper I guess)

BillB Oh OK a 'hub' gear thingy that's actually a BB. Wierd enough for me!

lukerative what about using a Schlumpf 2-speed bottom bracket - it woudl work fixed woudln't it?

http://www.schlumpf.ch/antriebe_engl.htm

I've read somewhere that the manufacturers say not to use it fixed