Let me say first, I don't enjoy riding trainers. I don't know if there's ever been a day where I've ridden outside and thought to myself "Man... I wish I was at home on my trainer." It doesn't matter how cold it's been while riding. I prefer to be outside.
Trainer riding can be very beneficial though. It's a controlled environment where you can get in the exact workout you planned on doing. No stop signs. No potholes. No coasting. No needing to wait on a group. You can get a really great workout in on the trainer, it's just never been enjoyable to me.
Trainer riding has gotten better recently. There are apps out like Trainer Road, CycleOps Virtual Trainer, and many others that make the trainer a little more interesting. Trainers like the bkool are becoming more and more popular, and give you the ability to race real opponents online. Other apps like Zwift are coming soon, and promise to be even more engaging than the ones we have out now.
These newer "smart trainers" like the Powersync, bkool, Wahoo, Computrainer, etc. adjust the resistance automatically based on the type of workout you selected. If you choose a route that has lots of hills, when you get to a climb it will become harder to pedal. You can shift to an easier gear on your bike to get up the climb, just like you would do in the real world. It's so much more engaging than the old "dumb trainers."
I'm not a trainer expert. I won't pretend to be. I think I may have ridden a trainer exactly once in 2014, and now a handful of times in 2015. I'm just going to talk about the trainer I bought recently. I've heard the bkool is awesome too, and if you are interested in talking to people first hand about that, there are a few in Oklahoma who are loving theres. I have no doubt that it's a great unit.
The older generation of magnetic and fluid trainers basically provided linear resistance. If you wanted to pedal harder, you shift your bike into a harder gear. If you wanted to go easier, you go to an easier gear. Pretty simple, and great for doing long intervals. You have a choice of videos you can watch while riding that have workouts incorporated. They tell you when to go hard and when to recover, and you manually follow along. Spinervals, Sufferfest, etc.
I haven't spent much time in Trainer Road, but from what I gather, it's an application that takes riding your trainer to another level. IF you have a plain fluid or magnetic trainer and don't have a power meter, it has "virtual power" to tell you your current wattage on the screen of your computer, tablet, or smartphone. If you do have a powermeter, it can read your actual power on the screen. You can create workouts, or use something like the sufferfest workouts in the app. If your aren't pedaling hard enough for the specific interval you are on, it will tell you to go harder. If you're going too hard, it will let you know. Pretty neat, especially if you are a data geek.
Let me give you some examples of what the CycleOps PowerSync can do using their CycleOps Virtual Trainer app. I have the bluetooth version of the trainer, so it works with any Bluetooth Smart devices (any iPads after the iPad2, some smartphones, etc). The software is $6 per month. Since I only plan on using it 2 or 3 months a year, that's really not bad.
In the "Routes" section it pulls up something similar to Google Maps. When you are zoomed way out, it gives you the most popular routes. As you zoom in closer, you'll see more and more choices. If you see a little video camera icon next to the route name, it means there is video of that route.
Once you choose a route, you can select whether or not you want to race a virtual opponent. These are real people that have ridden this route before. It shows you their finishing time before you choose them, so you can pick somebody close to your ability level.
As you are selecting a course, you can see the course profile (in pink, under the map), max grade, average grade, etc. You can also see your fastest time, and the fastest time by any rider.
Once you select the course, you just start riding. Smart Trainers like the Powersync will adjust the resistance of the trainer automatically when you are going uphill. The Powersync (made my CycleOps) basically has a built in Powertap (also made by CycleOps) so you can see your power on screen. Based on your power and percent grade, it tells you your speed. For example, 200 watts up a 10% grade might be 8mph. 200 watts down a 10% grade might be 40mph. If you have other bluetooth devices (heartrate, cadence, etc) you can also display that info on the screen.
There's multiple views you can have of the course. You can see the profile, and where you currently are in the profile (I'm the green dot at the start).
Or you can use google maps to see an aerial shot of the course. You can zoom in and out. You can use the standard map (street) view (it shows buildings and stuff in the city, just like google maps), satellite view, terrain view, or hybrid view. Here's what the redman course looks like in hybrid, zoomed in and then zoomed out a bit:
You can also automatically upload your ride to Strava, Traininig Peaks, MapMyRide, RunKeeper, RideWithGPS,Twitter, and Facebook. You can also email the garmin file to yourself so that you can manually add it to any other program like Golden Cheetah or PowerAgent.
Since it gives you an actual GPS file, when you upload to Strava it actually shows you in the location that you rode. I was in South Africa the other day and then Italy two days later. It also shows you all the KOMs along the route and where you would have stood up. This is also cool because you can see your average power on each segment.
With CycleOps Virtual Trainer, you can also do "workouts." You can choose one of the many workouts already in the app or make your own.
With the PowerSync trainer, all you need to do is pedal (i think this is the one thing the bkool lacks). The trainer will adjust the resistance automatically based on the workout. If you are supposed to do 280 watts, it will adjust the resistance to be easier or harder until you arevery close to 280 (it bounces around about 5 watts or so). If you drop below 280, it adds resistance to make you pedal harder. If you go above 280, it takes away resistance to make you pedal easier. In this mode, shifting gears does nothing. As soon as you shift, the trainer compensates and adjusts the resistance. If its set to 500 watts and you can't push that anymore, it basically just goes to a really hard resistance and tells you what wattage you are actually doing. The machine itself doesn't just turn you into a pro tour rider.
You can also race people. There are races setup that you can sign up for. I haven't tried this yet. I'm not sure if it is as cool as the bkool where you can actually draft off other racers, hear them breathing hard, and talk trash through a microphone. It's possible it does, but i haven't tried it yet.
You can also just "free ride." It's kind of like workout mode, but you can adjust it on the fly. If you want more resistance, you hit the "+" sign, and "-" for less. Like the workout mode, it adjusts the resistance to try and keep you at a certain wattage that you choose.
So that's a really long post, but the trainer really can do a lot. With all of that said, I still plan on ging out and riding in the 30 degree temps tomorrow morning. Even with technology, riding outside with friends is way more fun and interesting to me. On days where it's raining, icy, snowing, etc. it's nice to have a backup plan, and a smart trainer is a much more fun backup plan than the old dumb trainers.