Yeah, I know just mentioning vertical dropouts is forbidden here. Hopefully, someone will help me out anyway. I have an early 2000s Lemond Zurich (carbon/steel mix) with non functional gears. I have no interest in fixing the gears and riding a geared bike, nor do I want to spend too much money on the conversion which rules out that great ENO hub solution. My plan is to try find a 'magic gear' using a half link if needed. However, I realize that a chain tensioner will likely be needed. Here are my questions..

1) My preferred gearing is 42 x 16 (69 gear inches, using Sheldon Brown's calculator) which allows me to climb almost all the hills in my area. The Lemond has chainrings of 53 and 39. A 39 x 15 gearing will get me to 68.3 gear inches... is there anything else to consider or will similar gear inch measurements produce similar rides? I should mention that I only ride for fitness and strength training (which is why I love single speed bikes).

2) If I decide instead to go with a 42 x 16 gearing, will any road/track chainring fit the current 5 bolt Ultegra crank on my Lemond bike? Can anyone recommend a decent budget brand - I've seen a few deals on 42T FSA chainrings on Ebay - are these decent? How about for the cog - any recommended budget brands?

3) If I use the existing chainring and one of the existing cogs, can I keep the same chain or should I still upgrade to a single speed chain? I thought I had read that a 1/8" chain should be used for a single speed setup, regardless of if the chainring/cog was designed for a different chain - is this accurate?

4) If my "magic gear" wish does not work out, can anyone recommend a tried and tested tensioner? Does the extra friction associated with the tensioner, significantly impact bike speed?

5) Should probably be question #1 . What's the downside to converting the Lemond to a single speed? I understand that if I go with the magic gear I'll constantly be fiddling to keep tension after the chain stretches, but assuming I manage to maintain tension or use a tensioner, are there any other issues that might surface. I love the feel of the Lemond bike on the road, far more comfortable that the crappy stiff aluminum Leader single speed I've been riding.....faster too.

6) Lastly, out of interest since I cannot afford this solution right now, how does the ENO eccentric hub compare to a standard hub as far as speed is concerned - is there any sacrifice associated with the eccentric design?