Gear ratio

Is it wrong that I don't know this? It's mid-high 60s, 170 or 175 crank, on my commuter and higher on my track bike.

I'm tinkering with an old bike at the moment to go single speed with.
It's got a 50t chainring.
Thinking of going for an 18t sprocket.
Crank is 165mm
wheels are 700c
Gives me a gear inch measurement of 74.
Does that sound a bit high for ss?
It'll be used to ride flat only, with the odd mild incline.

I'm a bit new to the ratio game, so any advice would be welcome.
My other bike is running 38x 14

Law, that sounds perfect.

See Sheldon Brown's (rest in peace) website
http://sheldonbrown.com/gears/
Here is a SS / Fixie gear calculator link from his stie as well....does all the calculations for you. You just got to put the info in
http://software.bareknucklebrigade.com/rabbit.applet.html

I've been basing my possible gearing on other peoples recommendations for fixed gear bikes.
Now, don't shoot me down in flames for this, but am I right in thinking that the gearing considerations are the same for a single speed?
Obviously discounting the freewheeling downhill side of things!
I am building a single speed after all.

74 G.I is ok, You will struggle to find a freewheel bigger than 18 t anyway, or are you on a cassette hub?

White Industires do a 20t screw on freewheel. They are a bit expensive but re-buildable and are easy to change the bearing if they do go.

more skid patches the better?
Is that right?

more skid patches the better?
Is that right?

Yes.

It means skid based tyre wear will be spread evenly around the wheel rather than in one spot.

On freewheel it is a reasonable idea to have a slightly lower gear, considering that you do not have to pedal downhill. And if most of your pedalling is occurring on ascents, a high gear is probably not favourable.

back on 53/16 again after 14t proved too small for the cotswolds. Sheldon says 87.1 GI, do about 100m a week on it.

42/16 and spinning like crazy, everything's too easy around London, need more...any suggestions? Thinking 46/16...

For high Cadence & Tricks like Skids on wet and Dry conditions
46x19 is great. Like high spinning great cardio like Phil Cheng from Mash
46x17 once you have mastered all the skidding styles for a higher top speed and less spinout downhills

44 :16 fixed

Daily commute into Solihull.

57/16
No pain no gain!!!!

42/16 niceee <3

49:13 daily commute in Wolverhampton. Brought a 53t ring for the end of this year but I may be overstepping.

I'm about to move to Birmingham from Sheffield, where I'm pushing 44/18 up and down the hills. I'll be commuting between Harborne and the city centre at all hours of the day and night. I'm guessing the roads are going to be flat compared to what I'm used to so I'm going to 48/16 which is what I ride when visiting family in the fens.

Running 25:10 on 29er 2.35inch Big Apples.... That is, apparently, 72.8 inches....

Running 25:10 on 29er 2.35inch Big Apples.... That is, apparently, 72.8 inches....

Freestyling in Birmingham?

If you have excel you can try out my Track Gear Calculator.

https://www.dropbox.com/s/ll3sn1vwfhw8clh/Track%20Calculator%20Complete.xlsx