You'll have more options in studded tires for 26" than 700C. http://www.peterwhitecycles.com/studdedtires.asp For example, the mount and ground only comes in 26". How wide of a tire can your cyclocross bike take? I got 700Cx35 W106 for my hybrid, and they work well and have helped a lot, but I wish I had my mountain bike here so I could have gotten a wider, more aggressive tread/stud for when it's pretty bad out.