# Dual cogs?



## bmxking45 (Apr 3, 2010)

Just wondering if anyone runs dual cogs on the rear hub? I am thinking of perhaps trying to get this done so I can quickly adapt to whatever terrain it is that i am trying to ride. I also have an EBB so chain length should cause too much of an issue for me as long as he two cogs are not drastically different. If you are gonna post about just riding a geared bike then just keep it to yourself. I am a SS'er through and thru....its just that it would be nice to have a quick easy fix for very "hilly" terrain versus flatter conditions. Some pics of your setups would be pretty cool too.....HOLLA!!


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## boomn (Jul 6, 2007)

(in before the old grump tells you it's definitely not a singlespeed  )

Yep, I've done something similar but I don't have pictures. I ran two cogs out back and two rings up front. Kept the total number of teeth the same between combos (36+16 = 32+20) and adjustment wasn't really needed. Set it up properly and both combos still have perfect chainline. I used the 36+16 for around town and flat trails and the 32+20 for normal MTB. I got quick enough at switching that I would ride across town on the trails in the fast gear than switch it at the trail head.


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## bhc (Sep 27, 2005)

Sorry, I also don't have any pictures. But it is real simple to set up, as the boomn said, just make sure the teeth add up in both combos and you are good to go. Great for using a bicycle for commuting and off road. It helps to have it set up with a vertical drop out for quick changes, which you probably have since you have an EBB.


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## Orkje (May 3, 2006)

I've done the opposite: a ss rear hub with 1 cog, an old derailleur as a chain tensioner, and two rings up front. Gearing changes are done with a flick of a finger, and the two gears can be radically different.

Oh, and I second the "don't start about just riding your geared bike" warning. This is about changing gearing for radically different terrain, not because of a slight elevation change.


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## ernesto_from_Wisconsin (Jan 12, 2004)

DOS Freewheel: The clean simple lines of a single speed bike are undeniably elegant, but there are times when one gear simply isn't enough. In keeping with the simplicity single speeders strive to maintain, we developed the DOS ENO freewheel. Two gears on one freewheel. The chain is manually moved from one position to the next which allows the rider flexibility when riding in a situation that demands an easier or harder gear. We offer the DOS in sizes 16/18 (blue lock ring) and 17/19 (red lock ring). Made in the USA









Double Double: The Double/Double is a unique drive train system the we offer. The system is comprised of a double chainring machined from one piece of aluminum, mated with an ENO crank and a DOS ENO freewheel. The configuration for a 26" wheel bike is offered with a 38/35 big ring mated with a 16/19 freewheel. The 29er configuration mates a 31/34 ring with a 16/19 freewheel. The system works by either running the chain in the outer tooth positions or, alternatively, in the inner tooth positions front to back. The gear ratios are significantly changed when switching from one combination to another, however, the chain length does not need to be altered to accommodate the two differing ratios. Running the ring in the outer position tends to be more suitable for on-road style riding, whereas, riding in the inner ring position lends itself more to off-road riding.


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## ISuckAtRiding (Jul 7, 2006)

Orkje said:


> I've done the opposite: a ss rear hub with 1 cog, an old derailleur as a chain tensioner, and two rings up front. Gearing changes are done with a flick of a finger, and the two gears can be radically different.
> 
> Oh, and I second the "don't start about just riding your geared bike" warning. This is about changing gearing for radically different terrain, not because of a slight elevation change.


It's still cheating! you should have to suffer like the rest of us!


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## bmxking45 (Apr 3, 2010)

That is really cool but unfortunately I dont have a free wheel type hub. Keep the responses coming tho!!


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## Orkje (May 3, 2006)

> It's still cheating! you should have to suffer like the rest of us!


I wish I could.

I'd rather cheat a little bit than stop riding because my left knee starts hurting again. Long story. Started on a _geared_ ride three years back, and now rears its ugly head when ss'ing. How ironic is that?

Sorry to the OP. I did not mean to highjack this thread.


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## jackspade (Jul 23, 2010)

I am glad I use freewheel hub.

Does the chainline work if only use single crank?


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## Orkje (May 3, 2006)

> I am glad I use freewheel hub.
> 
> Does the chainline work if only use single crank?


I think it does. The chainline will be about 1mm off, but that should not be too terrible.


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## BrandonNorCal (Sep 16, 2006)

jackspade said:


> I am glad I use freewheel hub.
> 
> Does the chainline work if only use single crank?


Your brakes might not line up cause your wheel will be in a different position when you only use one ring. I have two rings and two cogs on one of my bikes. Works great. I can ride to the trail then switch it up and ride on the trail. Do a search for Dinglespeed.


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## MMcG (Jul 7, 2003)

I currently have 32:22 for trails and 36:18 for road/gravel on my 29er. Same number of teeth - so I can use the same chain and dont' have to move my Paragon Sliders either. 

It is an experiment right now........we'll see if it sticks.


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## umarth (Dec 5, 2007)

My, uh, dingle never worked quite right. Dingle'd front and back, ended up having to move the axle a bit, and then the brake rubbed. I think I was running a 38/34x16/20. Thought I had the chainline nailed, but then, I was using cheap chainrings that were (likely) oval. 

Also, maybe more of a rim brake problem. I did dingle in the back of my monocog with a single chainring without issues. I'm sure there is a lesson somewhere.


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## veloterra (Nov 21, 2008)

I run a 17 and a 20 on the the rear with a standard 9 speed freehub so I can change the ratio without removing the wheel. I run the 17 on the local trails and change to the 20 for the mountains or 12 hour races. I've used this set up with an EBB and sliding drops without issue. I set the chainline right in between both cogs with no spacer between them.


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## skankingbiker (Jan 15, 2010)

BrandonNorCal said:


> Your brakes might not line up cause your wheel will be in a different position when you only use one ring..


Please elaborate. I don't quite understand. :???: If he is using only one ring up front and swapping the chain between two cogs in back, why does the back wheel need to move?


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## umarth (Dec 5, 2007)

skankingbiker said:


> Please elaborate. I don't quite understand. :???: If he is using only one ring up front and swapping the chain between two cogs in back, why does the back wheel need to move?


A 18t cog engages chain than a 17t cog, which engages more than an 16t cog. In order to keep the chain tension the axle will need to be moved back and forth to compensate for the chain wrap.


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## skankingbiker (Jan 15, 2010)

umarth said:


> In order to keep the chain tension the axle will need to be moved back and forth to compensate for the chain wrap.


:madman: DoH! I misunderstood......thought you were talking laterally. My mistake.


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## buddhak (Jan 26, 2006)

ernesto_from_Wisconsin said:


> [/IMG]
> Double Double: The Double/Double is a unique drive train system the we offer. The system is comprised of a double chainring machined from one piece of aluminum, mated with an ENO crank and a DOS ENO freewheel. The configuration for a 26" wheel bike is offered with a 38/35 big ring mated with a 16/19 freewheel. [/IMG]


Where can a simple brother like myself get just the 16/19 WB freewheel without investing in the whole Double/Double kit and kaboodle?


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## buddhak (Jan 26, 2006)

Double post...my bad. BUT I answered my own question: Rivendell sells the 16/19t freewheel alone for $110 (ouch).


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## BrandonNorCal (Sep 16, 2006)

Just for Fun here is a pic of my setup probably from the wrong end that you want but here it is nonetheless


Dualcog by BrandonB00, on Flickr


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## meltingfeather (May 3, 2007)

why is this in the ss forum?


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## bmxking45 (Apr 3, 2010)

My new Surly 22T rear cog arrived and I will be picking it up today. Now it is gonna be time for some experimentation. BTW I am currently running 32x20 and am switching it up to a 32x22. Hopefully it works out for me well!


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## Mike Gager (Jul 30, 2010)

BrandonNorCal said:


> Just for Fun here is a pic of my setup probably from the wrong end that you want but here it is nonetheless
> 
> 
> Dualcog by BrandonB00, on Flickr


i would like to go to this setup on my bike, or something similar. could you use one of the aftermarket chain tensioners and simply have 2 chains that you swap out to change gearing? that way you could really use any cogs you wanted (i think?)


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## bmxking45 (Apr 3, 2010)

veloterra said:


> I run a 17 and a 20 on the the rear with a standard 9 speed freehub so I can change the ratio without removing the wheel. I run the 17 on the local trails and change to the 20 for the mountains or 12 hour races. I've used this set up with an EBB and sliding drops without issue. I set the chainline right in between both cogs with no spacer between them.


I would like to see a picture of this from directly behind the chainline...got one for me?


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## veloreality (May 10, 2009)

no longer pure.


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## bmxking45 (Apr 3, 2010)

Mike Gager said:


> i would like to go to this setup on my bike, or something similar. could you use one of the aftermarket chain tensioners and simply have 2 chains that you swap out to change gearing? that way you could really use any cogs you wanted (i think?)


^that my friend sounds like it would be more of a hassel than anything else. Swapping out chains would be a lot more difficult than just adjusting your EBB or dropouts.


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## boomn (Jul 6, 2007)

bmxking45 said:


> ^that my friend sounds like it would be more of a hassel than anything else. Swapping out chains would be a lot more difficult than just adjusting your EBB or dropouts.


doesn't have to be a pain at all. My horizontal dropouts take some fiddling to adjust properly in order to keep the wheel straight and the rotor straight within the limited clearance of the disc caliper (maybe its just my perfectionism though). In comparison it is very quick for me to remove and reinstall a chain using SRAM Powerlinks or some other quick link.


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## Mike Gager (Jul 30, 2010)

yeah after the initial setup was good i would think all it would take is a few minutes to undo one chain and put on another using quick links and readjusting the tensioner alignment which would only take an allen wrench in most cases. i could be wrong though


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## Cygnus (Jan 7, 2004)

i have two separate bikes permanently set up as 2x2, one on road, one off. each has two chainrings, 2 cogs with spacers replacinig cassettes, one chainlength. i've been riding one or the other every day for years with no issues. 

do a search on 2x2 or dinglespeed. or, go over to roadbikereview on the singlespeed/fixed board and do the same.

this is a reasonable place for your question, but prepare to take some abuse on the this board.


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## SaturdayKid (Aug 29, 2010)

boomn said:


> (in before the old grump tells you it's definitely not a singlespeed  )
> 
> Yep, I've done something similar but I don't have pictures. I ran two cogs out back and two rings up front. Kept the total number of teeth the same between combos (36+16 = 32+20) and adjustment wasn't really needed. Set it up properly and both combos still have perfect chainline. I used the 36+16 for around town and flat trails and the 32+20 for normal MTB. I got quick enough at switching that I would ride across town on the trails in the fast gear than switch it at the trail head.


I must have got this wrong but I thought it was the case that if both gear combo's added up to the same number of teeth then there would be no change in the actual ratio so it would be just as easy/difficult to ride whichever gear combo is used? Someone pls explain how the 2 combos differ even though they have the same ratio. Cheers


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## boomn (Jul 6, 2007)

SaturdayKid said:


> I must have got this wrong but I thought it was the case that if both gear combo's added up to the same number of teeth then there would be no change in the actual ratio so it would be just as easy/difficult to ride whichever gear combo is used? Someone pls explain how the 2 combos differ even though they have the same ratio. Cheers


because they don't have the same ratio, just the same total
32+20 = 52 and 36+16 = 52
but 
32/20 = 1.6 and 36/16 = 2.25

The difficulty of a gear ratio is based on how much larger the front ring is than the rear cog. 36/16 is a lot more difficult because there is a bigger difference in size between the two compared to the difference between 32 and 20


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## SaturdayKid (Aug 29, 2010)

Thanks for clearing that up for me boomn, I knew I must've got it wrong but wasn't sure what the explanation was.


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## boomn (Jul 6, 2007)

SaturdayKid said:


> Thanks for clearing that up for me boomn, I knew I must've got it wrong but wasn't sure what the explanation was.


glad to help


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## bmxking45 (Apr 3, 2010)

So after riding the 32x22 about 4 times I think i am just gonna completely remove the 20T cog that i have back there. The gearing is about perfect for my style of riding on just about everything. i am able to conquer climbs that on the 20T I could not and also pass over some terrain that i was unable to do on the 20T cog. i am very pleased with my decision!! Thanks for all the help and input!


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## wv_bob (Sep 12, 2005)

bmxking45 said:


> I would like to see a picture of this from directly behind the chainline...got one for me?


Not the same bike, but this is what my dingle looks like from behind


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## Guest (Sep 8, 2010)

LIke others have said, your no longer a Single Speed rider using two different size cogs.


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## boomn (Jul 6, 2007)

L09erdr said:


> LIke others have said, your no longer a Single Speed rider using two different size cogs.


and like I've said many times before... if they have no way to shift while riding and without partial disassembly of the bike, and especially if they have that beautiful uninterrupted SS chainline from ring to cog and back... then they're as much as a singlespeed rider as any rider who carriers a second cog with them or even owns a second cog.... they're just storing it in a more convenient location.

I always rode my dingle like a normal SS because it was. Having a second gear combo partially ready made it a lot less frustrating to switch over on weeknights to a faster gear for winter night rides around town for fitness and fresh air and then switch back on weekends to a mountain gear


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## Cygnus (Jan 7, 2004)

or, why care what is extruded from narrow minds. 

if you like the bike you've created, ride it.


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## dosbikers (Nov 9, 2006)

+1 :thumbsup:


boomn said:


> and like I've said many times before... if they have no way to shift while riding and without partial disassembly of the bike, and especially if they have that beautiful uninterrupted SS chainline from ring to cog and back... then they're as much as a singlespeed rider as any rider who carriers a second cog with them or even owns a second cog.... they're just storing it in a more convenient location.
> 
> I always rode my dingle like a normal SS because it was. Having a second gear combo partially ready made it a lot less frustrating to switch over on weeknights to a faster gear for winter night rides around town for fitness and fresh air and then switch back on weekends to a mountain gear


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## byknuts (Aug 9, 2008)

veloreality said:


> no longer pure.


there's no such thing as "pure" when it comes to an assembly of parts.


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