hubcyclist

So on the couple of occasions I've ventured outside to ride in the past month, I've noticed that I can easily ride about 2-4mph faster and at a higher cadence consistently compared to what I do on my trainer on comparable gear. Is the trainer (an old fluid one) providing that much resistance to slow me down compared to a paved road? Just feels like the effort is much easier in a number of ways for me outside vs inside. I imagine there are lot of variables at play, but wondering what some of those could be and if anyone else has that kind of disparity.

achoo

"MPH" on a trainer is pretty much meaningless.

Dunbar

This, although it's not unusual to be down 10% in power indoors vs. outdoors. Most trainers don't allow any coasting so you have to pedal for more of the revolution. The same is true of climbing and riding into a strong wind. If you do enough trainer riding you can improve your power in those conditions. Of course without a power meter (or a good way to estimate power) you can't really quantify this difference.

simonaway427

Ride at 20mph on your trainer, then let it coast down.

Ride at 20mph on the road, then coast down.

There's your answer.

Dudelsack 

Well. Mileage is mileage, but the power required to generate said mileage depends on the characteristics of the trainer and the road conditions. I can go 30 MPH down Wibble Hill at zero power but I can't generate sufficient power to do that on my Kurt Kinetic.

What would be interesting is whether one's FTP or numerous varients, such as the Carmichael field test, vary significantly from indoor to outdoor. You'd guess they'd be pretty close, but it would be cool to hear from anyone who has actually done it.

I only have an indoor power meter that derives the power value from the speed of the rotating cylinder on the Kurt Kinetic. It's accurate and reproducable, but when I ride outdoors I just kind of guess.

TexMac

Indoor trainers definitely feel harder than being outside and they are excellent for training especially when the weather is bad.
I like them a lot since they show cadence and power and you can find out quickly if you are improving or not.