# bigger cog, or smaller chainring?



## mcd (Jun 22, 2002)

i've finally settled on the ratio i want which involves dropping teeth, and i'm curious if there is any reasoning behind going smaller chainring or with a larger cog?


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## thurstonboise (Dec 30, 2006)

Gear inches are gear inches. Ratio are ratios.
There are people who say bigger ring & cog run smoother, and those that say smaller cogs cause your chain to wear faster. I believe the difference is negligible. Big rings look cooler to me.


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## JCavilia (Sep 12, 2005)

*no major difference*

but there are a few factors some people consider:

-all else equal, smaller gears will wear a little faster, and might wear out chains a little faster

-a cog might be cheaper than a ring

-aesthetics: some people like the big-ring trackie look


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## Richard (Feb 17, 2006)

A cog is definitely cheaper, but a chainring smaller than a 42 looks kinda weird.


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## ProsperityRed (Aug 21, 2007)

*my two cents*

Also depending on your BCD size you might not be able to use a ring smaller than a certain size. For example with a 144 BCD I don't think its possible to have a chainring smaller than 44 tooth. Although this depends on what cranks you have, with 130 BCD you can get down pretty low in tooth count. I have also found that the smaller cogs e.g. 13tooth seem to create more chain noise than the larger ones.

Whatever sizes you choose, I would recommend not going toward any of the size extremes for either cog or chainring just in case you want to make an adjustment later on it will offer more choices and flexibility later on.

Chainrings can go from 53t all the way down to the 30s and cogs can be anywhere from 13t to the 20s, the selection for both just gets a little more sparse as you get nearer to any of the ends of the ranges. I am personally using a 46t chainring and a 16t cog which lets me go up or down in cog size without too much trouble and doesn't require the swapping of chainrings.


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## PltJett (Nov 23, 2006)

Price. Depending on what kind of ring you are running, they can get stupid expencive.


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## ukiahb (Jan 26, 2003)

the standard track ring of 48 or 49t gives a good gear range w/ commonly available cogs. i.e a 17, 18 or 19 cog works well on the road for many, but big track gears are possible with a 14, 15 or 16t if you go to the velodrome, ride somewhere very flat, etc.....a gear of 80 GI + would not be possible with a chainring smaller than 39t


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## Tbirdbassist (Dec 2, 2007)

I have a 48t chainring and switch between a 17t and 14t cog(Formula fixed/fixed hub). Gonna try out that Surly dual fixed cog, Probably the 17/19t one, thought about the 17/20, but I would probably have too much spin while on the 20.


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## innergel (Jun 14, 2002)

Cogs are easier to change than rings.


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## JCavilia (Sep 12, 2005)

*I resemble that remark *



Richard said:


> A cog is definitely cheaper, but a chainring smaller than a 42 looks kinda weird.


As do the many of us who have converted road bikes and are using a 39-tooth ring. It does limit the high end, theoretically, but for the road I'll never need anything taller than a 39/14 (73 inches).


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## Richard (Feb 17, 2006)

JCavilia said:


> As do the many of us who have converted road bikes and are using a 39-tooth ring. It does limit the high end, theoretically, but for the road I'll never need anything taller than a 39/14 (73 inches).


Didn't say it wasn't functional. If the crankset I scored for a conversion had a 39, well I'd probably be running a 39 too. It just looks awfully small to me. From a purely aesthetic standpoint, I like the 48 on my other conversion.

My gearing is 42/16, right on about 71 inches - as big as I need to go for the street.:thumbsup:


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## roadfix (Jun 20, 2006)

If you're the OCP type just go with what looks best.


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## CleavesF (Dec 31, 2007)

innergel said:


> Cogs are easier to change than rings.


Huh? I'd rather deal with my 5 bolts than taking off my wheel, locking, cog, and doing it again. 

You should also consider that using a diff. setup means you need to alter your chain length. 

big ring up front, bigger cog in back, longer chain needed. Hopefully you have some travel in your dropouts so you don't have to buy a new one. :thumbsup:
________
Yamaha yzf-r125


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## roadfix (Jun 20, 2006)

CleavesF said:


> Huh? I'd rather deal with my 5 bolts than taking off my wheel, locking, cog, and doing it again.


I think most will agree that it is easier and more practical to replace cogs than chain rings.


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## tobu (Dec 19, 2004)

No, it's pretty much a given that it's easier and faster to replace a chain ring. Replacing a chain ring also allows you to fine tune your gearing as opposed to going up or down a full tooth in back.


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## roadfix (Jun 20, 2006)

tobu said:


> No, it's pretty much a given that it's easier and faster to replace a chain ring. Replacing a chain ring also allows you to fine tune your gearing as opposed to going up or down a full tooth in back.


True, I agree about fine tuning by replacing chain rings but as far as ease and convinience I find swapping cogs easier and faster.

EDIT: Perhaps I should change rings more often and find out for sure.....


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## threesportsinone (Mar 27, 2007)

And the Miche adaptor system (scroll down a little) makes changing cogs real easy, no more chain-whip.


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## asterisk (Oct 21, 2003)

threesportsinone said:


> Miche adaptor system


The Miche system has been known to develop play when used on the street without brakes. It's probably better suited to track applications or if you use your brakes to slow more than modulating the drivetrain for slowing down.


And while changing a chain ring is technically easier, changing the cog is both cheaper and reaps more change (1 tooth diff in rear roughly equals 3 teeth in front) so it depends on your desired results.


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## Stogaguy (Feb 11, 2006)

*Crossing Guard*

I am running a 39x16 on my mid 80s Univega fixie conversion. I agree that the 39:
1. looks small and a bit out of place.
2. is very functional given the hills I ride (and relative lack of fitness).​.
This was a "path of least resistance" conversion. I used the Shimano 600 cranks that were on the bike. Kept the 39 in the inside position (for proper chain line). Filled the outside position with a Salsa Crossing Guard. The guard gives the set-up a "finished" look and covers up the "funny" looking 39. It also make the bike safer to ride in street cloths for those ice cream runs with my 8 year-old daughter.


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## ukiahb (Jan 26, 2003)

In my experience it is much easier to change a cog than a chainring, especially for road riding. A one tooth cog change will change gearing roughly 5% and move the axle 1/8" in the dropouts, a similar change with a chainring will require a 3 tooth difference and move the axle 3/8", which could be enough to have problems with chain length, dropout travel, etc. For track racers it is worth the hassle of having several chainrings, cogs, and chains to get the gearing just right for a given event, but 5% jumps are close enough for road riding IMHO.


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## Touch0Gray (May 29, 2003)

roadfix said:


> If you're the OCP type just go with what looks best.



otay....since I care about cool..............that is why I ride and ride mostly fixed , ....50 tooth...best swap that back to the 52....and get me a smaller cog......


is winter over yet? I wanna ride more...and NOT in the house on the stand.................


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## wim (Feb 28, 2005)

Touch0Gray said:


> otay....since I care about cool..............that is why I ride and ride mostly fixed , ....50 tooth...best swap that back to the 52....and get me a smaller cog


Not sure if that's your size, but here's a very cool bike for sale  

- 58 cm c-to-t
- 6 rings: 64, 65, 66, 67, 68, 69
- 5 cogs: 14, 15, 16, 17, 18

Asking 1,650 Euros ($ 2,434)


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## Touch0Gray (May 29, 2003)

wim said:


> Not sure if that's your size, but here's a very cool bike for sale
> 
> - 58 cm c-to-t
> - 6 rings: 64, 65, 66, 67, 68, 69
> ...



ok..that's the one....lol.....that has a long a$$ head-tube.....guessing, about 1/2 the length of my seat tube......I am 5 foot 5 1/2 in the morning....before the day mashes me to 5 foot 5

One thing good about that is, if you get a flat, you can just ride on the ring......


Price is right though.........kids can live on less........


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## Tbirdbassist (Dec 2, 2007)

Would it even be possible to get that thing going without help? Jeeze!


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## Touch0Gray (May 29, 2003)

hill, wind or human?


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## wim (Feb 28, 2005)

Tbirdbassist said:


> Would it even be possible to get that thing going without help? Jeeze!


It's a stayer bike. The (motor) pacer starts first, then a helper pushes the rider up to running speed. The rider then slots behind the pacer and both slowly crank it up to about 35 mph or so cruise. During attacks, stayers can reach speeds up to about 65 mph for about two laps. Not for the faint-hearted, like me


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## Spunout (Aug 12, 2002)

This is a track bicycle for Derny racing (motorpacing on the track). You've got to get close to the pacer, hence the front end. 

Interesting to watch at 65km/h.


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## wim (Feb 28, 2005)

Nitpicking here, but strictly speaking, derny racing is not the same as stayer racing. Derny racing is done behind a moped without the roller bar (UCI regulated 100cc engine maximum), see photo. The racer behind rides a normal track bicycle. Of course, you're right about all of it being motorpacing on the track, and the word "derny" _is _used by many to mean all motorpacing. BTW, the UCI engine size regulation for the big stayer motos is minimum 500cc to maximum 1,000cc.

/


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## Jamieshankland (Jan 8, 2005)

JCavilia said:


> but there are a few factors some people consider:
> 
> -all else equal, smaller gears will wear a little faster, and might wear out chains a little faster
> 
> ...


1. Unless you run no oil on your chain and lube it with sand a fixed drivetrain will go a lonnnnnnnng time. Espessialy if you use half decent stuff.

2. You are correct, sprokets are also easier to get in the count you want. When in doubt 39x17 or 42x18. Tried and tru winter training gears.

3. Most trackies use rings under 48 tooth, espessialy the big guns who use their 13 tooth sprokets.


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## wil (Aug 23, 2004)

*Skid Patches*

In addition to all that has been already stated, I think you should also be aware of the number of skid patches, assuming that you are going to be riding on the street and ALSO assuming that you might be skidding/skipping, that a given gear ratio/combination will yield.

http://software.bareknucklebrigade.com/rabbit.applet.html
An online skid patch, and gear inch calculator.


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