# Chainring numbers



## Cadent (May 16, 2010)

Gentlefok;

Have a question about chainring numbers. I see references to such as: 39-13 but not real sure to what this is referring. Is this the number of teeth on two rings of a front derailleur, one 39 tooth (large) and the other a 13 tooth (small)?

If you have three rings, such as my fred bike, do you then quote all three numbers, in which case I would have a:30/39/50? Hmmm...that number scheme however, is way off from the previous one cited above, hence my confusion. I don't see how you can have a 13 tooth front ring...

OK, went back to the orig. post I was wondering about, and I gather the person was referring to a _gear_, 39 being the front and 13 being the rear?

Then a 50/39 reference would indicate a two-ring front derailler with a 50 tooth as the large ring and the 30 as the smaller ring, but no third ring?

Thx!

Don


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## Jett (Mar 21, 2004)

Cadent said:


> Gentlefok;
> 
> Have a question about chainring numbers. I see references to such as: 39-13 but not real sure to what this is referring. Is this the number of teeth on two rings of a front derailleur, one 39 tooth (large) and the other a 13 tooth (small)?
> 
> ...


39-13 measurement is not for the chainrings. It's for the rear cassette. Actually, it should be read 13-39. The first number is the number of teeth on the smallest cog and the larger number teeth on the largest cog.


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## Creakyknees (Sep 21, 2003)

Jett said:


> 39-13 measurement is not for the chainrings. It's for the rear cassette. Actually, it should be read 13-39. The first number is the number of teeth on the smallest cog and the larger number teeth on the largest cog.


Maybe... but not likely.

Much depends on context, and the reader's knowledge of standard sizes for these things.

For example, 53 teeth is the typical size for a big front chainring, although a "compact" set will often have a 50 tooth large ring. On older bikes, 52 was common. But you'd never see a 50 on the rear cassette of a normal bike. 

Other common chainring sizes are 39 and 42 for the small or middle ring, and 30 all the way down into the low 20's for the small chainring of a triple set (aka "granny gear").

Moving to the back wheel, cassette teeth have a narrower common range. 11 is the smallest production cog, while mountain and touring bikes can get a low/granny gear as big as 34. 

A typical road bike with double front chainrings and 10 cogs on the cassette, aka a "20-speed bike," might have 39/53 up front and 11-25 in the back.

So when riding that bike, you might be in your 53x11 (super fast, if your legs can turn the gear), or 39x25 for going up a pretty steep hill.


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## Creakyknees (Sep 21, 2003)

oh also here's a handy resource, listing many of the most common gear possibilities.

http://sheldonbrown.com/gears/


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## mtrider05 (Aug 8, 2009)

Jett said:


> 39-13 measurement is not for the chainrings. It's for the rear cassette. Actually, it should be read 13-39. The first number is the number of teeth on the smallest cog and the larger number teeth on the largest cog.


Negative. 39 would correspond to a standard small ring on a crank, while 13 is the number of teeth on that cog residing on the cassette.


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## Jett (Mar 21, 2004)

Creakyknees said:


> Maybe... but not likely.
> 
> Much depends on context, and the reader's knowledge of standard sizes for these things.
> 
> ...


When I saw 13 and 39 the first thing that came to mind was Campy's 13-29 10 speed cassette. 39-13 seem a little to small to be a front chainrings to me. 

Never really cross my mind that might have been a ratio. 

Sorry, for any misunderstanding I might have caused.


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## Cadent (May 16, 2010)

Helping a lot, thanks all...

Which next brings up why road bikes generally don't have a granny gear up front? I would be dead in the water without mine... I am pretty much dead in the water with it anyway.

At what point is it decided that one bike will have a granny and another won't?

My bike, for reference, is a 2010 Raleigh Cadent FT3 which is termed a "performance hybrid" meaning it doesn't have drops but it does have 700x32c tires.

I _guess_ the granny is a referent to its off-road pretensions, but "off-road" for th is bike would mean a flat dirt trail. A hybriized MTB it is not.

And interstingly, the 2011 Cadents have dropped the granny in the higher-end of this bike, offering just the 32/50 up front, while the lower-end Cadents have 26/36/48 up front.

So I am baffled about why mfgs. select the gearings they do.

Again, my 2010 Cadent has 30/39/50 up front.

As I look at these figures, the less sense they make to me. 32/50 doesn't give you a mid-range.. I live in my 39 most of the time. The new 26/36/48 is across the board lower than mine is now, a year younger... hmmm..... 

Opinions sought about why, as I said, mfgs. select the gearings they do.

Thx again!


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## pedalruns (Dec 18, 2002)

Let me see if I can help..... I'm talking just about the chainrings, up front... 

Traditionally bikes come with 2 chainrings up front(traditionally a 52x42 or 53x39 are the most common) or 3 chainrings which is called a triple... The triple, with the smallest ring was/is used for climbing or anyone that just might need the extra gear. 

In the last few years the compact came out... which is two chainrings, usually a 50x36 or 50x34 and the compact is kind of like a compromise between a triple and the traditional 53x39 or 52x42..... the main advantage of the compact is it is not quite as heavy and it gives you a few extra gears and some people don't need that smallest chainring in the triple... 

But I think you are getting it... It is really just a choice and a compromise by the manufacturers when they spec a bike with whatever type of crankset of what they think will sell..... The good news is we can choose which kind of crankset we want to ride.... For me I'me thinking of going to a compact from my traditional 53x39 to just gain a few more gears... I don't use my 53x12 as much as I used to, I'm getting old and I'd rather spin more!! I live in flat Texas, if I were lucky enough to move to Colorado, I'd really probalby consider a triple!


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## JCavilia (Sep 12, 2005)

Cadent said:


> Which next brings up why road bikes generally don't have a granny gear up front? I would be dead in the water without mine... I am pretty much dead in the water with it anyway.
> 
> At what point is it decided that one bike will have a granny and another won't?
> 
> ...



Most road riders don't want triples. Some feel this way because they really don't need the lower gears, some because of ego or pretense or whatever. Probably more could use them than admit it. Triples have some significant advantages (mainly, you can ahve a really low bailout gear while still having close ratios in the middle of the cassette), but some guys don't want to show any weakness ;-)

Full disclosure: I ride a standard double (39/52), and my lowest gear is 39x26. I ride some steep stuff, but there are very few climbs around here longer than 3 miles or so. If I rode often in real mountains, I'd probably treat my 60-year-old knees to a triple crank.

Most doubles are closer spaced than that 32/50, which is kind of unusual. Generally, a "standard" double is 39/52 (or 53), (42 used to be more common for the small ring), while a "compact" double is 34 or 36, with 48 or 50.


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## Cadent (May 16, 2010)

OK...sooo...back to the bike I know the most about that this point, my Cadent.

The high-end (such as it is) is the FT3 and has the dual crankset, whereas the lower-end (FT1 and FT3) have the triple crankset.

Do other brands offer a choice of dual or triple cranksets? I was at a pelotonia over the wkend and goggled at the bikes that came through the rest area I was at, and the VAST majority were dual fronts, the triples not being particularly popular for some reason. Saw my first DuraAce set... I felt very knowledgable.... <gggg>


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## Allez Rouge (Jan 1, 1970)

Cadent said:


> Do other brands offer a choice of dual or triple cranksets?<gggg>


Sure. Look at the web sites for some of the major bike brands ... Trek, Specialized, Giant, whatever ... you'll see that it is common to offer the same basic bike equpped with either a standard double, a compact double, or a triple. Often there's a nominal upcharge for the triple, say thirty bucks or so, but not always.</gggg>

With some manufacturers, the entry-level models are offered _only_ with triples; models in the middle of the overall price range can be had any way you want them.
<gggg>
Generally speaking -- but only generally -- the higher up the food chain you go in terms of a bike's retail price, the less likely you are to see triples. This is largely for the exact reasons JCavilia mentioned: riders that buy the top-tier, go-fast models are usually not riders who need, or will admit they need, gearing lower than can be achieved with a standard 53/39 crankset.
</gggg>


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## PlatyPius (Feb 1, 2009)

Cadent said:


> OK...sooo...back to the bike I know the most about that this point, my Cadent.
> 
> The high-end (such as it is) is the FT3 and has the dual crankset, whereas the lower-end (FT1 and FT3) have the triple crankset.
> 
> Do other brands offer a choice of dual or triple cranksets? I was at a pelotonia over the wkend and goggled at the bikes that came through the rest area I was at, and the VAST majority were dual fronts, the triples not being particularly popular for some reason. Saw my first DuraAce set... I felt very knowledgable.... <gggg>


Generally, the cheaper the road bike, the more likely it is to have a triple. Personally, I detest triples for more things. They're a pain to adjust, they have more "stuff", and they just don't work as well as a double.

Touring bikes should have triples. Beginner road bikes should maybe have triples (depends on the bike. I've found that some of them just suck no matter what you do to try to make it work better) Mountain bikes should have triples, for the most part.

I'm over 300 pounds, out of shape, and can honestly say that I've only wished for a triple on my road bike once or twice; but then I came to my senses. 

Triples are considered "n00b-sauce" cranks. As such, you aren't going to find a current-era DuraAce triple, an Ultegra triple, a Campy record triple, etc. Ergo, you aren't going to find any high-end bikes with a triple - they aren't going to put a 105 or lower crank on a DuraAce bike.

</gggg>


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## Drew Eckhardt (Nov 11, 2009)

PlatyPius said:


> Generally, the cheaper the road bike, the more likely it is to have a triple. Personally, I detest triples for more things. They're a pain to adjust, they have more "stuff", and they just don't work as well as a double.


Triples are awesome. With a trimable front derailleur as provided by Campagnolo they're easy to adjust for no rubbing in any gears even with 40.5 cm chain stays. For the same over-all gear range they work a lot better than a double by providing closer spacing between gears, less front shifting due to the increased overlap between rings, and better front shifting due to the smaller difference between rings.



> I'm over 300 pounds, out of shape, and can honestly say that I've only wished for a triple on my road bike once or twice; but then I came to my senses.


I still preferred a triple when I weighed 145 pounds and could ride over 20 miles in the Boulder, CO foot-hills during an hour-long lunch break ride.

When you get into serious climbs, even cat 1-2-pros are using low gears. In this year's Giro pros not sponsored by SRAM (their riders had to sell the triple using public on the new 34 x 32 compact double) were running gears like 34x29.

Most of the Rockies aren't as bad as the classic Hors catégorie climbs so you miget by with less; although most of us are a lot weaker and heavier than pros. In great shape I found that something like 42x28 was enough for any paved road.

When working hard on flat ground, aerodynamic resistance is increasing with the square of speed. Skipping two teeth between cogs like 19 and 17 makes for a 25% effort increase at the same cadence instead of 12%. 

If you don't want to give up those cruising gears for the flats without changing cassettes or wheels when you decide to go east versus west you need a compact double or a triple. 

I switched from a 52-42 x 14-16-18-21-24-28 to 50-40-30 x 13-14-15-16-17-18-19-21 when I got with the program and entered the brifter era. Having ideal flat and climbing gears was wonderful. When Campagnolo dropped the 13-21 I switched to 13-23 9 speed so I could keep my 18 cog (which is very pleasant at 18-19 MPH). After wearing out my chain rings I noticed that 34x23 was effectively the same as 30x21 and got a compact double which was a mistake.

In great shape as a 145 pound climber it was OK; although with more weight and less fitness it's not. With the right terrain, fatigue, wind there's a lot more front shifting and it's more involved. Without cross-chaining, the big ring on the compact crank is pleasant down to about 14 miles an hour and the small ring goes up to about 17. There are flat to somewhat hilly situations which involve a lot of alternating. On the triple, I could get 20 MPH on the middle ring and not need to get off it until dropping below 11 MPH making for a lot fewer front shifts. With the compact double, going up to the big ring is a dance involving a couple shoves of the right lever to get five cogs larger like shifting 34x14 to 50x19. With the triple it all happens at once like going up 2-3 cogs like 40x14 to 50x16 or 17.

Obviously, things get worse when you're bigger and at some point even a road compact ceases to be the best option.



> Triples are considered "n00b-sauce" cranks. As such, you aren't going to find a current-era DuraAce triple, an Ultegra triple, a Campy record triple, etc. Ergo, you aren't going to find any high-end bikes with a triple - they aren't going to put a 105 or lower crank on a DuraAce bike.


Real Men (TM) think you should be riding a double like them. 

The penny-pinching corporate bean counters want to make and stock half the number of front derailleur variants, a third fewer cranks type, and sometimes half the left brifter flavors than they'd need to sell triples in all their lines. That gives their marketing machines big incentives to keep cyclists away from triple cranks. The same business people especially don't want to be dealing with twice the number of bikes, especially where Real Men (TM) wouldn't buy the triple.

You can be a good sheep and corporate consumer, or you can think for yourself and use whatever suits your tastes.


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## PlatyPius (Feb 1, 2009)

Drew Eckhardt said:


> Triples are awesome. With a trimable front derailleur as provided by Campagnolo they're easy to adjust for no rubbing in any gears even with 40.5 cm chain stays. For the same over-all gear range they work a lot better than a double by providing closer spacing between gears, less front shifting due to the increased overlap between rings, and better front shifting due to the smaller difference between rings.
> 
> 
> 
> ...


Re-reading my post, I see that I forgot to mention people living in mountainous regions. When I lived in Wyoming and Colorado, I would have indeed preferred a triple.

Contrary to what I posted previously, I DO actually own a triple... a Rawland Sogn 650B bike with Record and a Campy triple.

The day I posted my first response, I had just replaced my THIRD triple crank on a Speedster S50 with a double because the TruVativ triple cranks suck.


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## SystemShock (Jun 14, 2008)

Triples are interesting, but I just can't use 'em... the Q-factor on modern triples sucks too much, and I'm one of those who definitely notices the difference 

I dunno, maybe BB30 can help fix this?
.


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