chromo vs stainless track cogs
 

Track cogs seem to come in two basic types of steel....either stainless or some type of hardened chromoly.

Many of the most expensive cogs are stainless and when looking at two equivalent cogs, the stainless variety is more expensive. For example at Retrogression, the All City stainless cog is $34, while the regular chromoly cog is $22.

What is the difference? Do the stainless cogs last appreciably longer or is it just about appearances?

I have been riding fixed for a long time and of the cogs I have owned to date (Surly, EAI, Miche, Shimano, Soma, and a few others), all are made of sort of hardened chromoly, but never stainless steel.
I have gotten pretty high mileage out all of these cogs and whatever minor differences I noticed in drive train smoothness faded with the slightest amount of cog wear.

What am I missing? Is there some reason to pay more for a stainless cog?

Good question. I don't have a definitive answer, but I will say that there could be marketing reasons involved. In some industries, a product made out of stainless will command a premium regardless of cost. The manufacturer is merely taking advantage of the consumer's perception that it is better. They can capitalize on the allure. This happened with titanium also. Everything up to and including golf balls have used the word titanium as a marketing ploy. Then there is the copper craze, where you can get copper-infused socks and now copper-infused face masks. Does it do anything? Yes, it separates you from your money.

Getting back to cogs, I doubt the manufacturers have done extensive testing of one vs. another, except perhaps corrosion-resistance, but I'm going to bet that the difference in wear is likely to be negligible. Stainless is slightly lighter than CR-MO, so it has that going for it if weight is a factor. I can't imagine it adds up to much though when a single cog is considered.

There is one other factor that might effect the retail price and that is the cost of the raw material. Perhaps billets of stainless are simply that much more expensive?

And the last possibility I can think of (and I don't know that it applies here) would be the cost of production. I've encountered some instances where a finished product cost more to make in one metal versus another. That was because of the way the metals behaved, extra time and extra steps were required to get the same end result. Like I said, I have no idea whether that is in play here or not.

It will be interesting if someone in the industry knows the real reason or reasons.

One difference in the All City cogs is that the SS is advertised as a "high polish" finish whereas the CR-MO is not. That alone adds cost. I'm not arguing $12.00 in extra cost, but some extra cost.

Actually chromoly steel is harder than stainless steel, so it should last longer. There is really no good reason other than cosmetics that I can see to pay more for a SS cog.

We are talking gear cogs. All that matters is that it is made of quality hardened steel and the teeth cut to a good shape. Yield and breaking strength (the sought after properties of chromoly) doesn't matter at all. (When was the last time anybody broke a cog?) Neither does corrosion resistance unless you do your riding underwater.

In this context, chromoly, chrome plate and SS are fluff. So is a high polish. I ride the EAI cogs because they wear well and have cogs shaped to resist throwing the chain. (Best done with very little shaping!) I also like that they print the number of teeth on them. Saves me time. And no, the EAI cogs are not the quietest or sexiest. But downhill at speed, they are the cog I want my chain running over.

I have 2 or 3 SS cogs simply because in the large sizes (23 and 24 teeth, there aren't lot of choices. I picked up a Surly 17 when I needed another that size, It has a sexy finish and nicely shaped teeth. I will only use it on my best fix gear; not because it is that good but because that bike has a Sugino 75 crankset and I can set the chain with less slack and not fear throwing it with those shaped teeth.

Ben

^^^^ you made a believer outta me