Thanks for sharing. I have two thoughts on this:

1) I said in another thread (and was challenged on this) that it is easier to make a good runner out of a good biker than the other way around. You may have encountered the phenomenon right here. In the general case, I think that cycling needs more quad - lower back strength which comes from muscles that good long distance runners just don't have. Sprinters, on the other hand, - who, having massive quads - make excellent bikers.

2) You may have been riding with large gears and low cadence - requiring more quad strength. Try using smaller gears and spinning up the cadence a la LA. I think your running has trained up your cardio fitness at the expense of your quad strength, so adapt your cycling style to your new engine and rely more on the heart-lungs to do the work.

PoC

I don't remember the details, so I won't pretend to, but I read an article in Runner's World about a year ago about how bike workouts can be used as substitutes for some of your weekday runs when you are marathon training. The key is not substituting the long run, which is usually on the weekend and if you're working on speed to leave a speed session in your plan.

In my personal experience when I started year round triathlon training my total time run only training was less than when I only did running events, but my plain ol' straight up running race times got faster. I can't say that is directly attributed to the biking, but I think it helps. In my case it seems to help minimize the fatigue and stress on my body.

One thing I also recall from my reading about the bike for run swap is that if you had an hour run planned on a particular day and want to "sub" a bike workout, a bike workout for an hour would not be equivalent. You'd probably be better off with a 1:30 bike that day. (I think...you'd need to confirm)

Different things work for all of us though, that's just been my experience, which was similar to what I read in RW...and which I only vaguely remember now. (I'm really helpful, right?)

Thanks for all the advice.

This last Friday I managed to get a good bike workout in, and today my legs feel ready for a good bike workout despite the long run yesterday. Maybe I just needed to get through the initial adjustments. I'm only up to 14 mile long runs, so I've still got a way to got. My target is the Freescale marathon in Feb. I am only running 3 days a week and biking and swimming the other 3 days a week still overlapping workouts with bricks except for the long run and my hard interval run. My bike rides are just 2x36 miles.

I actually go more for time. I know miles are what will matter in the end, but adding a prescribed amount of time each week is so much easier and seems to correlate better with total fatigue. My long run pace is 6.8-7.2 mph avg, so right now I am just cracking 2 hours on my long runs. My other two runs average out to half of my long run, so my total weekly distance is double the long run. I plan to add another run to the schedule next month. I do just one run with hard 6-8 minute intervals. That's 45 min to 1:15. I do another short run with about half at pace or all at long run pace depending on the total weekly volume . My long runs are done with about 1/3 of the time at race pace (8mph min) split into two intervals whose length varies by the total distance. I'll probably max out around 60 miles in a week. This week I'm at half that, but I'm three months out. I'd like to work up the volume early enough to really dial in the speedwork.

I often go on rides when I'm "supposed" to be doing a light run/recovery. Cycling is low impact and definitely helped me with active recovery. I also noticed that my run improvements did not suffer as I integrated this training into my schedule. I also felt less guilty, as I was still able to claim the training miles on the bike for the week!