My bike is new and I'm not planning on doing this "mod", just curious. My DT Swiss LN freehub comes stock with an 18 tooth ratchet mechanism. There appears to be 36t and 54t upgrade kits being offered. In what situations would someone benefit from these upgrades? I'm a roadie, not a racer nor do I ride in extreme situations. I understand they increase the engagement response, but for an average rider?

Just wondering.

It's a subtle difference and the only difference is the reengagement lag when you start pedaling after coasting.

You'll notice it the most it fairly high speeds like when you're coasting down a hill and want to start peddling again to climb the next hill.

If this isn't bothering you now, save your money for something where you'll feel more benefit.

It's not bothering me at all. Just curious and wondering if there was something I was missing.

There is some debate on the "robustness" of the 36 and 54t "upgrades" vs the 18t. The more shallow engagement angle of the higher tooth count ratchets might be less robust....I believe the new 350 hybrid hubs are going to come 24t when they come out.

My Hybrid 350 hub has the 18t and I find it perfectly adequate as a road biker. I did have some trouble with engagement within my first 100 miles but my dealer cleaned some grease off the teeth, put it back together (in about 30 seconds) and all has been well since....

I weight 280#, so durability / robustness is a key factor for me.....

Well, 18 POE is 20* of wheel rotation, 36 is 10*. Does that matter when the wheel is spinning reasonably fast?

Seems that this would matter more for MTB, when going slow and using really low gear ratios with larger diameter tires (29ers). Possible it helps on technical terrain?

I think so, especially when one is plodding uphill? 20 degrees is quite a bit.

Let me also be the first to point out that going from 18T to 36T freehub doubles the frequency of the angry swarm of bees effect while coasting at speed.

The 18T feels genuinely slow on a mountain bike, and possibly could be meaningful for cyclocross and possibly crit racing on road. Fast engagement doesn't really make much difference for most road riders. I have done a lot of road/CX riding on low engagement hubs and it's never an issue for me.

On a mountain bike, it's a pretty small amount of the time but 18T makes timing pedal strokes when I'm worried about pedal clearance. 36T is fine, higher than that is probably useful for those who regularly ratchet through sections or utilize some trials-like skills.

You are not missing anything. Perhaps if you were riding trick bikes you'd want really close engagement. Otherwise it is a total non-issue that some folks like to hype.