Bat56

You guys are probably right. 20t to 16t actually five teeth, so I will correct the math. But a track end will probably handle that. I go from 19 - 21 on my commuter between summer and winter but I have not tried more. The problem I have is that I use a fender which ends up pretty far back with the smaller cog. But I do not know if people use fenders on touring bikes... I would.

But that does not change the fact that this means the magic gear is out and the tensioner is in.

JohnDThompson 

I used a floating chainring on the timing chain of my tandem. It had an annoying tendency to pop out on rough roads. Maybe it works better on a shorter chain.

drjaa

I use a dropout chain tensioner on mine (horizontal dropout) not for the chain tension but because rear wheel keeps on sliding forward no matter how hard I tighten the nut.

79pmooney

[QUOTE=Bat56;17640707Track ends cannot take up four teeth worth of slack...[/QUOTE]

Huh? That's a short track end!

spectastic, get the tensioner. Ride the vertical drop bike. When a frame with horizontal road drops comes along that fits the rest of your needs, buy it and swap the parts over, skipping the tensioner. It won't matter if that happens in the next 1000 miles or 20,000 miles. The vertical drop bike will work just fine. The new (probably old) frame will be a step up that you never regret, but until then, vertical drops and a tensioner will serve you just fine.

I haven't used a tensioner. But it is simply less than 1/2 of a derailleur, and requires virtually no adjustment. The concept is well proven over most of a century. Buy a second after you are convinced you like the first. Then when the bike falls over, you can replace it before straightening out the damaged one. (A luxury harder to justify with a derailleur bike where those "tensioners" cast far more!)

The point is to ride. Sometimes we have to ride what we have. My first fix gear was far from perfect, but it got me started down that road. Next frame was a big step up, but the first bike served me well. (Not say you should ride fix gear at all! It is just my first love, and has been since my first ride on that lousy bike 39 years ago. A decent vertical drop frame and tensioner with an IGH hub will be a big step better bike than that first fix gear, by a lot!)

Ben