In lieu of a zillion factors...

I have a CK single speed hub and a 19t and a 20t cog. On the crank I can run either a 39 or a 42.

I've never tried to find the magic gear, but is this enough of a selection to find one? I'm looking to run a single speed CX series on a bike with vertical drop outs. I'm much stronger this year, and I'll be far more competitive than on my steel single speeder that I ran last year.

Since I've already got a blingy and expensive back wheel, the old ENO eccentric recommendation is a no-go. And although I like the idea of the EBB30, the customer support from Beer Components has been less-than-woeful (half a dozen e-mails, ranging from informational to courtesy to technical, all unreturned --- BTW, everyone in the world has kids, or a vacation, or a dead Mom, or a dead cat, or a tough life, blah blah, but Bill Gates answers his f###ing phone, just participate in reality and respond, especially if you run a business) and I will never give money to stoners that don't respond to basic communications.

Is magic gearing an art? Not too much in the way of trial and error with only four possible combinations.

I think we worked it out that each tooth that you add would move your rear wheel 1/8th of an inch forward. Chains are 1/2in pitch. You could just get one of those handy dandy chain tensioners. Magic ratios are possible, but with chain stretch and limitations on gear selections, why bother?

Magic gear calculator:

https://www.eehouse.org/fixin/formfmu.php

1/8 **********? I thought is was a quarter inch.

I think we figured 1 link, in plate + out plate is 1 inch.

Split that 1/2 on top run and 1/2 on .................

Never mind.

See, this is hard. Just run a chain tensioner.

LOL every time this subject is brought up theres a 19 thread debate on whether its 1/2 1/4 or 1/8 inch change per tooth

Just get your LBS or this guy (https://www.pinkbike.com/buysell/1364408/) build you a wheel on WI eccentric hub. I had Dave (pinkbike link) build be one for my MTB - run it fixed on gnarliest trails and it rocks. My mtb is old cannondale frame with vertical drop outs which I like a lot and I wanted to run it fixed so eno hub was perfect solution. I have freewheel (splurged for WI as well - bombproof and engagement is second only to fixed) on it just in case but 99% of the time it is on fixed side:

BEER is a one man shop done on the side. Jim at BEER is a solid guy. I know him personally. Just had his first kid so he is sleep deprived. His EBB's are solid and work extremely well. They are on most of the SS CX bikes around here. If you have any direct questions feel free to PM me.

damn. thats hot

Get yourself a DMR chain tensioner.

I love it - all my bikes are steel (grew up on steel bikes and like the feeling) and that's the only alu frame I got. But cromo fork and low pressure tires take care of harshness and it climbs like a goat. Fixed is 32x16 and 17 freewheel. rear is 26 inch and front is 29er