Gearing?
 

When I ride my SS MTB on the road I use 32/14 with 2.1 Panaracer Fire XC's which according to Sheldon Brown gives me a 59" gear. With my fixie I plan on 46/18 with a 23-25mm tire which is a 67" gear. Any idea how these 2 would compare? Would the decrease in rolling resistance make up for the bigger gear? With the MTB the 32/14 is great around town unless I get a strong headwind.

As I said, I run this setup in San Francisco and it works great. Never ran anything smaller. Did 46x17 before and that was great too. Try it out and see what you think. Gears are very personal. And you should have no problem selling a slightly used 18t cog if you deside to get a 19t or 20t.

I believe you are asking a fitness or skill level question.

What are you trying to accomplish ? A constant speed ? For how many hours ? A higher rate of speed ? Bursts of speed ?

It is all relative.

I run about the same 32/14 on the SS mtb, mostly on forest roads and easy singletrack, the road bike is 42/18. I like it because it gives me a rather high but even cadence. Some days it feels very easy others hard. But the excercise is good for me.

I just built my first single speed with a 42/16 gear. At first I experimented with a 48/38/28 triple in front, matched to the 16 rear with a Melvin tensioner to take up the slack. Initially I thought 42/16 would be too low a gear on the street. But I live in a hilly area and don't think I could climb in anything bigger - at least not for now. Although I'm coasting more of the descents I seem to get to work in the same time as on a multi-geared bike. I guess because I make up the time grinding up the hills in a higher gear. Whatever. I'm having a blast on the single. Life is complicated, bikes shouldn't be. DanO

46 18 would be perfect... for me.

You should try some out and see what fits. Likely you'll grow into gearing rather than fit perfectly anyway.

i got 52 x 17, but i guess its because i tend to travel rather quickly, works for me though

My fixies range from a 42x16 to a 52x16, and I learned on a 42x18.
I can climb with all of them but actually find it easier with the higher gear.
My 44x16 puts me in a gear that's too light to stand with yet uncomfortable
to pedal uphill for long stretches while sitting.