I have a 48:18 about 70 GI and I live on an island that is nothing but mountains... big ones...

it's a little (no its REALLY) rough going up some of the steeper hills (ive had to walk more than a few of the big ones), but for the most part its all good..

and its nice to not have your legs spinning out of control on the downhills and I can skid no problem..

I really do wish I had a 17t cog tho, it will be harder on the hills, but then Ill have 17 skid patches instead of 3.. heh