Sluggish Legs for 2nd week - Winter Training

I always think that riding the turbo is harder than riding the road, even if the numbers (HR monitor / Power meter) suggest otherwise.  

Have you taken any time off? Might be an option. Rest mind, body and soul between summer and winter. You'll soon be fresh again. 2 weeks should do it. 

For most this is a time of declining FTP not rising. We rest, we recover, we return stronger.  

After workout or after a hard ride do you use a foam roller on your quads, thighs, abductors, calfs, glutes? Stretch the IT band? Have you tried drinking chocolate milk which contains an optimal mix of carbohydrate and protein to help refuel your body after a hard ride?

What does your tss and IF look like compared to a typical summer week.

If you normally ride at high IF and are now doing base you are using muscle fibres that
don't get used and neglecting the ones you use in the summer so trying to ride like its summer isn't going to work because that fitness has dropped off in those fibres. My tss and IF are way down but my legs are killing me because I ride hard on the summer.

Good news is sticking with base and then moving on to build should give you a better 2017.

Don't know if I can help you out- only to say that I've had a similar issue past couple of weeks.

Went on a reasonably calm ride around the Peak's for a 40 mile loop, at 30 miles I hit the biggest climb of the day (which unfortunately I HAVE to go up to get home!) and although my HR was way below threshold, my legs just refused to play along feeling like they were just clogged with lactic acid.

Similar instance happened the weekend before- although I put that down to the loop being longer (60 miles). 

My winter bike is heaver and with fatter tyres and less gears- but I'm sure this wasn't enough to explain the extra suffering I was going through! I'd also spent a bit of time on the trainer, but only 2X 20 minute interval training. 

Hope it's only temporary and the legs will be back to normal soon!

If your FTP is up on the turbo, then I'd struggle to believe you are overly tired. 

Is your road set up adn turbo set up the same? 

How have your turbo sessions gone since the poor road rides, are they also bad? 

Echoing comments above, it is slower out there. 

My power is a little down, which I put down to clothing resistance, more strain on respiratory system, but also, the speed generated from those watts is clearly down as well.

This is as much as 3kph... 

1 to 2kmph average speed reduction is the accepted loss for winter rides it seems. 5 to 10% more drag due to air density alone, then you add in the extra drag from clothes, a little bit more from the rubber, and a tad from your own physical difficulty in riding in cold. Bit of weight from winter kit can add seconds here and there too. They keep tracks at 29 degrees as its best for both riders to warm up in and faster speeds due to lower resistance.

Look at your Strava segments and click on Full Leaderboard on them all, vast majority will be in warmer months, bar the occasional roaring tailwind days or whatever. Should read April to October, with most being in June to August. Can't simply chalk that up to being everyone peaking magically from their awesome structured training plans that they so rigidly adhered to  

I'm on around .5 to 1.2mph drop in average speeds on rides from feel -1 to 5 degrees. Had some shocks recently so read up a lot on it and feel better now. Was expecting to be faster cos I did a ton of miles in September. Seems not. 

Plan now is to get my averages back to summer speeds during the winter. If you're not on form AND are getting hit with winter speed loss, then you can get quite a shock too. Indoor trainers are boss though, don't think you're cheating yourself cos you've been using it instead of going outdoors. Work done is what matters to your body. Other stuff is ancillary and less important.

I've just had a month off because my knee has been playing up and my legs felt strong as anything on the hills when I got back on. Maybe you did just overdo it and you need a propery recovery period.

Turbo trainers may be the devil's work though. I usually end up going harder overall than I would in real life or just cramming more effort into less time because there's only so much you can take of looking at the garage walls even with Zwift or whatever running.  

Winter riding is usually harder - cold air is denser and you're wearing more flappy layers. From your comments that sounds very much like a virus, particularly as other family members have colds. Even if it isn't I'd ride really steadily for a few days and get plenty of sleep.