I've read in quite a few places that many people switch their front tires to 120/70/17's from the OEM 120/60/17 tire (if so equipped from the factory). The reasons that I have read for doing this is for quicker response, more grip, better street ride, and more race tire options (since alot of race rubber is not available in 120/60/17). I do realize that the geometry will be altered slightly, but can be compensated for by lowering the front the same amount that the taller apect ratio tire raised it (so about 12mm).
However, is there any big reason not to do it? My CBR600F2 came with a 120/60/17 front tire from honda, and they must have designed it this way for a reason. However, many old designs can be improved upon. I'm about to buy new tires, and both 60 and 70 series are available. Which would you choose, and why? I'd ideally like to hear from those who have used both sizes on the same bike so i can hear some concrete before/after info.
Thanks for any input you can provide!
P.S. My intended use for the bike is daily use (weather permitting) as well as a handful of lapping days per summer, if it makes any difference. Thanks again!