After a long time away from the bike I am fixing up my old 1990 Cannondale 3.0 for more casual bike path riding.

With the 700x25c tires on there now the minimum clearance is about 10 mm from the top of the tread (brake caliper) and 7 or 8 mm on the side (chainstays). The tires measure 24 mm wide so they are reasonably truthful 25c's I guess (others I have seen are more like 21mm).

I would like to put a wider tire on for a little smoother ride and to better deal with rough surfaces. Given the clearance I have is there any reason why a 28c tire is a bad idea? I know wheels, etc., flex a little when pedaling hard.

Thanks for your advice.