IF I do any cardio, and that's a big if, it is always after lifting. I used to walk on the treadmill for 20-30 minutes before lifting, and my lifts suffered as a result. Nowadays my cardio is mostly walking my dogs twice a day and maybe a bike ride on the weekend (non lifting day).

i was bike commuting long before i started with weights - around 15 miles round trip, total time around 90 minutes/day. i guess originally i just added the lifting in on the days when it was time to lift, but i've been deloading for the past week or so and i'm not really sure what my new pattern is. i'm also between contracts, so only doing the 'commute' ride when i feel like it now, compared with 5 days a week pretty consistently, whether i want to or not.

for what it's worth though: now that i've got more serious and started stronglifts, i think i'm finding it's the lifting that beats up the biking, more than the other way round. i've been going to the gym every alternate day, pretty consistently. on a sl day, i can ride out there, rest briefly (no working day in between), ride back and detour to the gym, do my workout, come home . . . no real problems. but the day AFTER a sl day, when it's just a bike ride, i'm not exactly speedy gonzales these days. i don't seem to have the muscular oomph to get myself much out of breath. my legs give out long before the lungs start to fuss.

and i think too it depends on what your priority is. i could ride harder, and be more casual about lifting weights, as i was in the beginning . . . and that seemed to work fine. currently i'm more interested in lifting more aggressively, so i'm willing enough to put my focus on that and just ride with whatever feels like it's left over afterwards. i do agree however that you can ride three (or four or five) days in a row without very much ill-effect . . . but i don't think i would want to lift 'heavy' weights for three days in a row.