yes, i probably gave the impression i know less than i do--don't get me wrong, i don't know much. but when i got the newer bike with 700s in june, i had only been on the bike for about a month, so i knew even less than i do now. all i can remember is that they were 650s. i think we upgraded to 700s because they were: 1) more readily available (the shop didn't even stock 650s); 2) available in more widths; 3) more suitable for what i was doing. i had a pinch flat on both tires at the same time because of a sewer grate i had to bike over (rather than swerve into a bus). the theory was that wider tires wouldn't have slid into the grate, which is how the @#$% flats happened. i had four flats in a month with the skinny 650s. in the four months with the 700x28s i had no flats.

the shop guy also said to get a beater bike for winter. but soon i'll be upgrading from my current bike anyway-- so my current road bike which should eventually become my old beater bike won't be suitable for winter. erg! this can be a very expensive activity, especially the first year. -- good thing i love it

I *think* (and I could be wrong) is that your bike shop is saying you won't be able to stuff 28s with slight knobs or tread (aka "semislicks") in your frame.
yeah, that's what they meant. i don't explain vey well-- not enough knowledge. after further research on-line, i find skinny tires are okay for loose snow. packed snow is better with knobby ties. who knew? thanks, pedalfaster. all replies are helpful for the newbies