Bicycle Mechanics - 9 rear / 3 front versus 10 rear / 2 front

I am starting to see more bikes which are doing away with triple chainrings up front, going back to doubles, and the inner chainring is rather small, and then 10 gears in the rear. Instead of 3 front, 9 rear. Specialized Sirrus is an example of this, the top-end model is that way.

So you go from 27 combinations down to 20, and you reduce the rotating weight up front, and reduce the extreme chain angles.

But do you really keep the same range and increment that you had with 27, when you had a "granny gear" chainwheel? Which could be very important for touring in hilly country?

I am starting to see more bikes which are doing away with triple chainrings up front, going back to doubles, and the inner chainring is rather small, and then 10 gears in the rear. Instead of 3 front, 9 rear. Specialized Sirrus is an example of this, the top-end model is that way.

So you go from 27 combinations down to 20, and you reduce the rotating weight up front, and reduce the extreme chain angles.

But do you really keep the same range and increment that you had with 27, when you had a "granny gear" chainwheel? Which could be very important for touring in hilly country?

No you don't. With a "road" triple crankset you can go down to 24 teeth in front, but the "compact doubles" can't take a chainring smaller than 33 teeth, and most of them are bigger than that.

Also, the biggest rear available for Shimano type 10 speed is 27, while 9-speed cassettes are available with sprockets as large as 34 teeth.

For touring in hilly areas, there's no comparison.

Sheldon "9 For Hills" Brown

+-------------------------------------------------------------+
| Just remember that given the range in ages, geographies, |
| abilities, and needs, the "average" in "average |
| recreational rider" is going to span quite a distance. |
| What works for a 20 year old male in Florida is not going |
| to do much for a first-time female rider in Colorado. |
| --Kirby Krieger |
+-------------------------------------------------------------+

Available gearing is actually a lot more complicated than what your question addresses.
There are also 10-speed triples available, 3 in the front, 10 in the back.
Plus there are compact doubles as well as conventional doubles.
If you are trying to make a purchase decision it should be made on where you ride as well as how strong of a rider you are.

Al

Conventional double: 53/39 chainrings, generally (sometimes 52/42), 130mm bolt pattern
Compact double: 50/34 chainrings, generally; 110mm bolt pattern
Road triple: 52/42/30 chainrings; 130/74mm bolt pattern (could go 53/39/24 for widest range)
Compact (for road) triple: 46/36/24 (or 50/36/24 on my bike); 110/74mm bolt pattern.

The compact double is lighter and simpler, and with 10 speeds people can get siginficantly lower gearing on a road bike than a traditional double with 9 speeds.
Basically, a compact double allows lower gears than a conventional double, mainly because there's more of a difference between large and small chainrings. 10-speed cassettes allow one more sprocket option than 9-speed. So you can get a wider range of gears.

But for touring in hilly areas, you should just go with a triple. For regular riding in hilly areas, though, a compact double can be great.

I've got a triple, but since updating to a 9-speed 12-26 cassette, I have yet to use the small chainring. I just use the 50/36. But the small ring is there, in case I ever need it...

With Shimano, doesn't matter if it's 10-speed or 9-speed, your lowest factory road cassette option is 27-tooth cog. Correct me if I'm wrong, but I don't think 10-speed gives you any better range unless you built a custom (e.g. 11-27) cassette - the widest range available stock is still a 12-27, but with the 10-speed cassete you pick up a 16T cog (12-13-14-15-16-17-19-21-24-27).

With 9-speed, you can go to an MTB cassette (with an MTB rear derailleur) for a 34-tooth low cog.

Shimano 10-speed doesn't give you a wider range if you were already running an 11-27 9-speed. But if you were running a 12-23 9-speed with a 53/39 and want to move to a compact double crank, then 10-speed increases your range b/c you can go 11-23. Also, if you're running a 12-23 or 12-25, you can add a larger cog if you go 10-speed, to 12-25. If your goal is widest range, then this ain't useful - just go with MTB stuff. But if you want a wider range with less weight, greater simplicity, and without big jumps between cogs, then 10-speed with compact double is nice and useful.

Yes, the advantage of 10-speed is the extra cog in the middle, right where it is needed.
With Campagnolo a cassette with a 29 cog is available, as well as triples and compact doubles.

Al

With Shimano, doesn't matter if it's 10-speed or 9-speed, your lowest factory road cassette option is 27-tooth cog.

"Road cassette" is a marketing term for medium/close ratio cassettes. It has nothing to do with "road-ness."

Shimano 10-speed maximum sprocket size currently available is 27 teeth, but with 9-speed you can go as big as 34 teeth with a suitable derailer.

Shimano uses the marketing terms "road" and "mountain" to refer to what more properly would be called "close/medium range" and "wide range" cassettes and derailers.

Until the late 1980s, different marketing terms were used, they were described as "racing" and "touring" derailers respectively, which is actually a bit more accurate than the "road/mountain" bs.



Correct me if I'm wrong, but I don't think 10-speed gives you any better range

That's an undestatement. 10 speed gives you a much worse range than you can get with current 9-speed stuff.

If the past is anything to go by this will change in coming years. The same situation obtained in the first couple of years of the transition from 6- to 7-speed, and from 7- to 8-speed, and from 8- to 9-speed. It's easier to make good shifting stuff for closer ratio clusters, so that's what they always start out with.

You'll start seeing wide range (so-called "mountain") 10 speed setups probably in the 2007 or 2008 model year.

Sheldon "Seen It All Before" Brown

+-------------------------------------------+
| Ah, but I was so much older then, |
| I'm younger than that now. |
| -Bob Dylan |
+-------------------------------------------+

I like to look at it this way. The cassette in the back is your gears. The chainrings up front are "speed ranges". Don't think of a triple with a 9 speed cassette as a 27 speed bike. Without cross chaining, what you have is a bike with three speed ranges. The high and low speed ranges have 8 gears each. The middle speed range has 9 gears.

A double simply has two speed ranges insteady of three. On a compact, you are just lowering these speed ranges a bit. You are simply trading out top end for bottom end.

One nice thing about a triple is that you can run a tight cassette and still have great gears for climbing AND descending. If you don't live in the mountains, you probably have no need for one, because you just don't need the low speed range. If you do live in the mountains (I'm not talking hills), they come in really handy. And then having the 52 or 53 / 11 is really nice on the way down.

It comes down to buying the right gearing for your terrain and riding style. There are a lot of people out there buying what the fashion police are telling them to.

Remember that things run in trends. The bicycle companies will change to something different just to get people that already own a good bike running out with their $$$ to buy the newest thing. It's like wide ties, skinny ties, back to wide ties.

It really depends on your personal preferences and abilities, I think. I built a hybrid for myself, with the main goal of durability and simplicity in mind. MTB frame - road components, mostly. 7 in back - 2 up front. I found that my friends with 27 and 30 speed bikes weren't doing any better in the sandy stuff than I was with only 14. I did convert to a "compact" crankset of sorts - found an older biopace and put together a 36-46 ringset. If I know I'm going to be in the dirt I put on my 13-30 freewheel - if it's gonna be a road ride I have a 12-21. Maybe it's the local terrain, but I don't have any problems keeping up with my buds.

Except for racers, I think all the advantages of the 10-speed doubles lie in the hands of marketers: narrower chains and cogs (probably less durable too), more expensive replaceable parts, etc.

There are two advantages to a double, and I think they are not good or important for the "ordinary" road rider :

– Quicker shifting of the front derailleur, because it's basically left or right. But unless one races, what difference does 0,2 second makes?

– Real Racer (TM) look. Real racers (TM) generally have doubles, but their team replaces gears according to the terrain.

Amongst the drawbacks, one important problem of the double is that the change over between small and large chainrings occur around the most useful gears. This means for lots of "time-consuming" double-shifts which are easily avoided with a triple.

Available gearing is actually a lot more complicated than what your question addresses.
There are also 10-speed triples available, 3 in the front, 10 in the back.
Plus there are compact doubles as well as conventional doubles.
If you are trying to make a purchase decision it should be made on where you ride as well as how strong of a rider you are.

Al

Agreed. I went for triple 10s due to most of my riding being in hilly areas and for long distances. There's no shame in triple for me, but it is funny when I ride past loads of walkers who let their pride lead them to a racing double setup!

One thing I forgot to mention in my previous post...the Shimano 10-speed brifters are much nicer ergonomically than the 9-speed models.

If I were going to set up a new bike with derailers and serious touring gearing, I would use 10-speed brifters, but with a 9-speed cassette (using the Alternate Cable Routing (http://sheldonbrown.com/derailer-adjustment.html#alternate) setup.)

Sheldon "Contrarian" Brown

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| If a man does not keep pace with his companions, |
| perhaps it is because he hears a different drummer. |
| Let him step to the music which he hears, |
| however measured or far away. -- Thoreau |
+------------------------------------------------------+

I like the 3x6 half-step-plus-granny gearing I put on the Peugeot I'm selling: 52-48-34 / 14-16-18-21-24-28. I used an old school mountain crank with a 110mm BCD. It works well with a Shimano 600 front derailleur and a long-cage Peugeot-labeled Simplex rear. I'll bet a serious tourist could easily substitute a 14-16-18-21-24-28-32 7-speed freewheel, to get almost down to 1:1 drive.