Looking at adding a Surly Dingle Cog to my Cross Check and am wondering how much I can get away with in terms of chainlength variation between the various cogs. Wanting to go for as much range (in terms of gear inches) as possible.
I’m currently running 49x17 and am looking at getting a 17/21 Dingle Cog and using it with my current 49 and then adding a second 46, 44 or 42 tooth chainring up front.
Now obviously the 49x17 / 46x21 combo is only 0.1" apart, so I’m taking it for granted that it will work fine. However, what about the potential 44x21 or 42x21 combos? Is ~0.5" to 1.0" inches too much of a variance?
I’m thinking I should be able to take up that slack with the space in the horizontal drops, but then again I don’t want to be slammed in the back of the drops at 49x17 and nearly falling out in front at 44x21, either.
Thanks in advance, I know this is noobish but I don’t have the parts in front of me to easily answer the question myself.
The addition or subtraction of a tooth in the cog will move the axle about 1/8". A 21/17 dingle would have a 4 tooth jump so you would need about a half inch of adjustment room in the dropout.
Pardon, that didn’t address the ring question. I doubt you will get away with anything as big as a 49/42 pairing with the same chain. The 46 might work.
Thanks, that’s what I’m thinking too. I wish there was a way to pull it off with a 42T (since I’ve got a nearly new stainless steel Surly 42T chainring on hand) or that the Dingle came in something like 17/23 but alas it’s probably not to be. 1 full chain link is probably too much to be comfortable (i.e. not able to tension with the big combo and nearly falling out with the smaller combo).
I’d consider having a four tooth difference on the chainrings (buy a 45 tooth ring) so that you don’t have to move the axle at all, much easier to change the ratio at the roadside.
Actually a 45T ring will have more axle movement than a 46T, given the four tooth difference on the 17/21 Dingle. But yeah - your sentiment is spot on. Plus I’m running/rocking/rolling/rubbing a rear brake, so there’s that to consider as well.
Anyone wanna swap me a 110bcd 5 bolt 46T in good shape for my nearly new 110 bcd 5 bolt Surly 42T?
Just to clarify, 49x17 and 45x21 would be the same chain length. If you wanted 49x21 would need about 1/2" forward movement in the dropout. 45x17 would require 1/2" back.
you can’t shift on the fly with a dingle cog/double front, can you?[/quote]
You’d have to be REALLY handy with a hook and pedalling REALLY slowly.
But in the real world, no, you’d have almost no chance.
With the Eno double freewheel it could probably be done by a skilful hook user.
Thanks guys for reiterating. I admit I am relying on that chainlength calculator I linked to above, and it makes it seem like the 46x21 is a closer match to 49x17 than 45x21. Is it wrong and/or am I simply an idiot?
Don’t trust that calculator. In any case the variance between the chain lengths for 49/17 and 45/21 using the calculator is 4mm which, if it was true (which it isn’t), wouldn’t cause a problem.
Anyway, here’s what they say on the Harris Cyclery site:
I think my Dinglecog setup is going to be 48/45 x 17/20, with something slightly above 80 inches on the other side of the hub. Maybe not enough of a spread. I could go 17/21 in the back instead.
Anyone know if the chainline would be acceptable from the inner ring to the outer cog or vice-versa?
And yea, I’ve thought about a Paris-Roubaix front or rear derailleur for the Dos Eno. Would be neat.
