Surly Dingle

Could i run a derailler with one of these?

no

definately not.

how come?

It be like running a chain tensioner fixed. It does not work because of back pedaling.

ah yes....bugger....might still have a fiddle with it. HMMM wanders off to fettle and fiddle......

Not For Fixed Gears Nor Coaster Brakes

Chain tensioners are only usable with freewheeling hubs. They must not be used with fixed gears or coaster brakes, because these allow chain tension to be applied to the lower run of chain when you backpedal, and no chain tensioner is built to withstand this force.

• from sheldon brown (RIP)
  

might still have a fiddle with it.

Just don't let anyone catch you. If you do get caught pretend you were trying to get a spider off of it.

http://www.youtube.com/watch?v=pqnUceOIEHE

thank you nelson....will still fettle....

This is a bit out there (just sort of looking at feasability)

but could you combine this with a flip/flop?

what do you mean? the dingle is designed to have two cogs at rear, combined with two chainrings up front. some run one chainring up front which compromises chainline.

but yes, you could have a dingle on one side and another cog on the other, although you may find that you do not have enough dropout length to get correct chain tension. if you want three gears, why go fixed?

do you ride fixed at the moment? because you will probably never be bothered to keep undoing, moving, flipping, and tensioning the chain just for a hill or whatever. htfu!

Just interested in the mechanics of it.

3 gears is getting a bit messy, like I said though just investigating the feasability of it

Thread dredging a little.
but I'm interested in the concept of having 2 gearing on 1 wheel without chainging chain.

The idea is to have a 44/17 for road and 40/21 for polo
I have a double fixed hub. Is it worth getting one of those double cogs or am I better off buying an extra 21t cog but having to flip the wheel around (it means I can also keep a 1/8th chain)?

My chainring is dead so doesn't enter in the equation.

My question is really about chainline problems if you see what I mean.

Buying a Dingle sort of defeats the object of a double fixed hub. Chainline won't change from one side of the hub to the other, whereas with a Dingle you'll have to get another chainring to get perfect chainline. Get another cog, cheaper.

yes, but I do want a bigger gap, if you see the two gearing options, they are pretty far apart.
You cannot do that if you only have one chainring cos drop outs are never gona be long enough to cater for the bigger cog.

My question is, if I flip the 2nd cog (flush side nearer the center-line) and use it with the inner chainring, will it cause chainline problems?

In the ratios you've posted above, the second ratio has four more teeth in the back and four less teeth in the front, compared to the first ratio. You should need the exact same chain length, and thus shouldn't need long dropouts at all.

(disclaimer: this makes sense in my head, but I've never tried it before.)

yes, exactly my point, I don't want a different chainlength. Therefore I need 2 chainrings, giving me two different chainlines and therefore, I also need two cogs with different alignment.
Is reversing a cog going to give me the same alignment as the second chainring ?

OHHHHHH, i get it.

In that case, yeah, a dingle would probably be awesome for the application you're describing.

:D phew!
Chain wise, is running a 3/32 chain going to make a huge difference?
I'd really like to know about the reversed cog chainline if anyone tried that before.

a reversed cog's alignment depends on the cog. it may hit the spokes. but it reality, having them both on the right way, its only a few mm. few mm is nothing. but a dingle would be the most elegant solution.

This would work brilliantly for you, fixed adaptor for freewheel cassette hubs, thus chainline will likely to be more precise than the dingle;

except that means buying a new hub and spokes and rebuilding a new wheel which is totally unnecessary for the minute benefit in chainline that it may/may not bring.

Dredging time, I'm getting more and more keen on the dingle cog, however I preferred to use it with a single chainring (got a 3/32 chainring luckily), but worried about the side plate rubbing against the cog, perfectly feasible?

don't need to have a 100% perfect chainline, as long it's not off by too much.

Do you want to buy my Schlumpf Ed?