When crossing North York East to West or vice versa, I try to use bridges with no ramps to the DVP/404... these are McNicol between Finch and Steeles, or Van Horne.
Up in Markham, the safest East West routes in my opinion are John St which becomes Center St in Yonge, and further up North, 19th. North South in Markham is Kennedy although crossing the 407 is a bit hairy if you are not used to it. To avoid mixing it up 407 ramps, you could take Rodick Road between Warden and Woodbine. Much farther East, the best North South road in Markham is via Reesor as the 407 goes above it. I am hoping the proposed tunnel under the 407 along Birchmount (no ramps) will be completed soon although I prefer using a bridge as opposed to a tunnel for visibility reasons.
The hairiest part of any commute or road bike ride for me is whenever I have to cross any 400 series highway (401, 407, 427, 400) where there are ramps and you are forced to mix it up with cars, trucks, and worse, 18 wheelers.
Last edited by cyclocommuter; 02-28-09 at 12:44 PM.