thanks for all of the advice ladies and gentlemen, i need a 17t, i'll look into ordering an EAI.

Sure, but you'll wear out 3 of the Al cogs in the time it would take you to wear out the steel one.

For me, Dura Ace for 13-16t. Euro-Asia Imports for 17t.

Dura Ace is world class and the cheapest. What more could you ask for? This photo is from the mechanic's station of some world-class event (Germany I would guess based on the flag sticker). Notice the Dura Ace and EAI cogs.

Soma cogs are remarkably similar to Euro-Asia Imports cogs in look and feel (and font). Not sure if there is any relation between the products.

That EAI cog on the "13" post looks awfully big...

Someone was in for a surprise when they went out to race with that on.

Iv ridden Dura-Ace, Surly, and cheap no name. The Dura-Ace and Surly are exactly the same in noise and wear thus far. The cheap no name was a piece of junk.

16 and below Dura Ace, 17 tooth up soma.

Is the stainless CK worth the $42?
Is it smoother, more durable or quieter than a DA or Surly?

Thanks

$42 for a cog is sure cheaper than a pair of the king hubs.

I use all-city and am pretty happy with it

I don't get it. CNC is the surface finish right? It doesn't tell you how "reliable" a cog is. Also, being stamped won't probably make a cog softer or anything. Hardening is probably done after stamping, because it doesn't make sense to stamp a hardened steel. Thinning is probably a problem, but you know people use 3/32 cogs right? I think those are wicked thin, but they don't break do they?

That being said, most CNCed cogs are identical and you don't need to inspect the cogs to guarantee that you are getting just right. Some stamped cogs so uneven, you lay em together and you can see they are significantly different. I could pick up a CNCed cog on a fly and expect reasonably identical performance.

Drive efficiency we need to ask people like Carleton who do real track work. I am pretty sure even flat contact surface directly results in performance improvement. But then for those people, I am sure, the flex of chainrings also matters. ... Totally different world to a casual street cyclist like me.

P.S. Lately, I am beginning to see really cheap CNCed cogs. Like the one from Steelwool. Those sell like 15-7 in Tokyo. Beats my stock stamped cog by 5 bucks. Geez. Those any good?

Wrong. CNC is an acronym for "Computer Numerically Controlled", which is a type of milling machine that is extremly precise and can automatically replicate a machined item to very high tolerances. It has nothing whatsoever to do with the hardness or finish of the item. CNC'd items can be hard or soft, and the finish can be durable or not.

I think you guys are saying something similar in that CNC is just the cutting process. It doesn't speak to the metal's strength or durability.

correct, i could put a hersheys chocolate bar in a CNC machine and have it cut me a track cog. it may be near perfectly shaped, with great, tight tolerances, but its still made of chocolate.

No; it's just prettier.

+1

you do know they are non-threaded?

https://chrisking.com/parts/cogs

dang...no phil love?

my drivetrain is 100% 1/8"...ring, chain, cog. i started with a surly stainless. found it a bit noisy, but not crazy. chainline was very good. hub threads were a bit loose/sloppy...just a bit. teeth were clearly stamped, w/sharp edges. durability (again, good chainline) was excellent...5k miles at removal and i happily kept it as a spare. looks perfect.

then went to the cheapest EAI (black machined steel). far superior, for very little more cash. buttery smooth & whisper quiet. black coating was barely worn after another 5k. sold the surly, made this the spare...

...and picked up a phil. holy bling-TASTIC, batman. every bit as precise as the EAI, with completely smooth organic curves, no trace of machine marks, and a mirror polish. i thought it would get dirty and disappear, but after ~1k mi on an otherwise maintained but used/dirty drivetrain, it still shines on. worth every penny...don't knock it 'till you've tried it.

mildly related: i used a king alloy SS cog on a cassette-hub SS mtb. teeth/splines were plenty strong for the torque, but the teeth wore quickly in XC conditions. steel would have been a better choice here. not sure how this translates to road, but for $20 more, i'd take the certainty of steel. no doubt the king is a quality product, so why not go for the more durable material?

wait...you need threaded. EAI black. period. end of discussion.

My Stock TT still works after 500 miles...lol....why upgrade!

My GF's Kilo's cog showed noticeable wear before 500 miles.