Depends on how many times you've said to yourself "Damn I wish I *really* had a 16 tooth cog right now." The extra gear doesn't increase your gearing range, it just sticks an extra one somewhere in the middle.

Personally, I see no reason for it, especially if you've already got a bike set up.

I wouldn't spend the money to change from DA9 to DA10 if you have your bike all set up - but I would buy a new bike at DA10 if I had the choice.

That being said I did switch my tri bike to DA-10 because I got a new road bike with DA-10 and wanted to be able to swap wheels back and forth without changing cassettes. It was very easy - all I did was get a new chain, new front deraileur and put the 9-speed bar end shifter on friction. I already had a DA rear deraileur and I used a 10-speed cassette from my road bike set up. The nice thing about switching a tri-bike vs. road bike is that the shifters are the most expensive part of the upgrade - you do not need new cranks.

jhendric,

Did you just pick the 16 tooth cog for lack of a another one or is it specifically the 16 tooth cog that you get?

In actuality, the 16 tooth cog is the cog most commonly ridden in by most recreational cyclists, whether they realize it or not. Those who have had it and give it up, discover this right away.

FWIW, IMHO, the 16 is not a good cog to give up.

Just my 2 cents on the subject of 16 tooth cogs.

---

Ben Cline


Better to aspire to Greatness and fail, than to not challenge one's self at all, and succeed.

12/25 (9-speed): 12,13,14,15,17,19,21,23,25

12/25 (10-speed): 12,13,14,15,16,17,19,21,23,25 (I'm guessing here)

I'm just guessing that it's the 16 they include with a 12/25. Never had it before. Can't say I've missed not having it. Just out of curiosity, how do you know that the 16 is the most commonly ridden cog? I can see it on a fixie, where it's somewhat standard to run a 42x16, but that's not comparing apples to apples.

It is a shame that people recognize the difference between Dura-Ace 10 speed and 9 speed as just being one gear.

Realistically, that is the most insignificant of the many technical differences and upgrades from 9 speed to ten speed.

These differences are much more significant than the addition of a single cog:

• Lighter.
• Crank uses solid chanrings that are significantly stiffer side to side than 9 speed resulting in much faster, quieter shifts with less lever travel (particularly important with long cable length, bar-end shifters in aerobars). Benefit: It is much easier to shift 10 speed from the small ring to the big ring using a bar end shifter and the new Dura-Ace 10 speed crank and chainrings. The shift happens faster and requires less lever travel.
• Bottom bracket integrated into crank assembly for increased strength and durability and lighter weight.
• More durable rear derailleur with some forged components.
• Stiffer front derailleur with forged body parts.
• Better barrel adjusters on brake calipers.
• Narrower, lighter, easier shifting chain.

The difference between Dura-Ace 9 and Dura-Ace 10 is not one cog. It is a significant leap in shifter, drivetrain, crank and bottom bracket technology with features and benefits that are a significant and tangible improvement over previous 9 speed versions.

---

Tom Demerly
The Tri Shop.com

 On slight inclines I always found myself wanting that 16. I also had 4 cogsets to find match the gearing to the course, but what do you do when a flat course has long or steep hills, not the 11-21. I could replace the four 9 spd sets with two 10 spd sets and have all the gearing I would need for any race.

You are spot on about the upgrades from a product standpoint, but from a user perspective for me it was all about the 16 tooth cog, that was always the cog I wished I had, except on pancake races where the 11-21 covered me.

Personally I was unable to feel any difference in shifting performance between the 9 and 10 speed components that I changed (frt & rear der, chain, cassette, bar end shifters). And by the way I do not like the adapter they used to make the rear SIS bar end fit and shift correctly, not as clean or solid as the 9 speed set-up, it just a small thing I notice every ride.

All in all it was a great upgrade for me on the tri-bike, but I do not see changing the road bike out unless I break something major like the DA 9 STI levers.

As for advice, ask yourself, how often have I wanted that one extra gear, how much difference would that cadence make over the course of a race even if you were only in that gear for 2 miles?

jhendric,

I believe I first saw mention of this in the questionably "authoritative" source, Bicycling Magazine some number of years ago. I had been cycling for only a few years at that point. This hit home particularly after I had ridden a wet and windy century when I spent a considerable part of the last half in no man's land trying to push one gear that was too hard and then push the next gear that was far too easy. This was the original cassette on my bike, an 8 speed triple with 13, 14, 15, 17, 19, 21, 23and 25 tooth cogs. You guessed it. The 15 tooth cog was too hard and the 17 tooth cog was too easy.

The next cassette that went on my bike was a 12-19 straight block. I was much happier with this gearing over the previous gearing I had had.

I had always been led to believe that straight block cassettes were only for the pros and the most fit recreational cyclists, something I was not. But I had learned that having the tightest gearing for the terrain or conditions (windy) one was riding meant that one was more likely to have the "right" gear ratio to peddle and make the engine/legs happy.

That was the end of wide range gearing for me. Now, if I don't have the right gear when I'm riding, they don't make it.

I've seen additional articles supporting this original piece. It may have been the same author in different publications over time, I don't know. I think I have also seen information to this same conclusion on Sheldon Brown's website.

---

Ben Cline


Better to aspire to Greatness and fail, than to not challenge one's self at all, and succeed.

Interesting. Thanks for the information.