Trainer vs Road miles

Cash? What's that? Med student here, haven't seen cash for awhile now! 

My tri-coach told me not to bother with the computer while on the trainer.  He mentioned it was not as accurate as it should be on the trainer.  So I just use my watch and count for a minute, whenever I feel my body either speeding up or slowing down, or if I change the resistance.  I just "guesstimate" distance, based on what I do on the road and how my body feels.  If I do a speed session for an hour, and I know my cadence was 90+ for the entire time, I'm pretty confident I went at least 17 miles, if not further.  So I put that down, no matter if I feel like I "went further."  At that point I just think to myself, "you just kicked your a$$ for an hour, your HR was good, you've got a pool of sweat under the bike, the dog is going nuts trying to lick your legs, the kids squeal when you hug them (in a good way)...it's been a good ride!" 

When I'm on the trainer the only thing I look at is my heart rate and cadence.  I don't worry about miles or anything, as has been said they aren't real accurate on the trainer. 

When I log my workouts on BT, I just guesstimate the mileage based on what I know I could do outside for the same period of time. 

This has been said a few times, here, and I for one could use a bit more explanation of what precisely is meant.

I can understand that the TRAINING effects of pushing some particular gear at some particular cadence will be different indoors vs. outdoors -- I don't need that explained. So if that's what folks mean, then fine.  I get that point.

But if I'm pushing gear X at 95rpm for an hour, and I traveled 17 miles outdoors, then in particular I traversed the circumference of my rear wheel some given number of times (17 miles divided by the circumference of the wheel).

Now, if I do that same gear X at 95rpm for an hour on the trainer, I will have traversed the circumference of the wheel that same number of times, so in some sense, I've 'traveled' more or less the same distance, right?

but distance is a poor metric of effort.

I can go out and coast for 30 miles down a hill , or I can climb that same hill. 

Both ways I did 30 miles: are the workouts equal?

1. I hold the same speed for both workouts:  Are the workouts equal?

2 .I could hold the same effort for both workouts (uphill wold just take longer): are the workouts equal?

No, they aren't.

1.  In the downhill, you are putting out little effort (little power).  In the uphill, you are using a lot of effort (lots of power).   It takes the same amount of time and the same distance, but I worked a LOT harder climbing.

2.  I hold the same effort (or power) for all 30 miles, but I hold it much longer for the uphill.  The overall workout is harder again going uphill, as I'm sustaining the effort longer.

power is the ultimate metric for cycling, but after that is some measure of effort (like HR) and time.  Distance and time are too variable to have meaning on the trainer, as resistances can vary so much.  Distances on the road (for similar terrain) do translate well, because the resistances are very similar.  If you calculated your overall total average resistance on flat asphalt (which is a function of speed) and calibrated your trainer to match, then trainer miles would somewhat equate road miles.

x2

As a recent survivor of grad school, i would bet that part of the reason pegasus doesn't ride on the roads more is that she might be riding at odd hours, such as well after dark (I know I had that problem for a while). A little bit of practice and you can get pretty decent at reading/studying on the trainer as well.

Buying a powermeter is a huge investment, but if you're riding on the trainer most of the time you could try a Kurt's Kinetic stationary power computer ($50, http://www.kurtkinetic.com/kinetics-power-computer-p-46-l-en.html I use one of these on my trainer and while they're tuned to work on the Kinetic machines, they come with instructions on how to tune them to other types of trainers.

Mileage isn't important so much as time and effort (via the power computer). bear in mind though, that an hour on the trainer is probably going to be more tiring than an hour on the roads, there's no coasting on the trainer!

I ride a considerable amount on my trainer. It is more accurate than you think.

 1) When you ride outside there are hills (both up and down) and your speed can vary greatly.

 2) On a trainer, you ride. There is one resistance (unless you have some fancy schmancy adjust on the fly thing-a-ma-bob).

 3) At least on my trainer I tend to keep the resistance level fairly high, so it is like I am riding at a slight uphill all the time.

Why would the mileage be different? If you use the same computer that measures your distance based on revolutions of your wheel, how would it be different indoors vs outdoors? The only time there would be a difference is if you are using a GPS unit, indoors vs outdoors will be different then. 

It seems like people do not want to believe they ride 'so slow' on a trainer, because outdoors they are faster. It is harder to ride on a trainer in almost all conditions except massive outdoor hill climbs. 

Huh?  I have no thing-a-ma-bobs, but I can change the resistance by just shifting gears.  Low gear = low resistance, etc. 

True.  The GPS indoors would be zero.  That'll make for a pretty big difference. 

Yes but in that gear, you have 1 resistance setting, without hopping off the bike and tightening the resistance on the tire.

I agree that it's likely just as accurate. It's a different type of effort so we're always going to feel slower on the trainer. I was frustrated to be averaging 12-14mph on the trainer when I could do far better outside, but I'd have to ride outside with no wind and on a totally flat surface to simulate trainer conditions.

I log my time and miles straight from the computer and it's always lower than what I can do outside. I note that it was on the trainer for reference, but I don't give myself the extra miles I could have done if I spent the same time outside. I feel like it's a great workout when you can't get out and ride, and for me right now, it's all I can do while I'm recovering from injury. And like others have said, I don't compare my trainer rides with road rides, but I do compare my effort from trainer ride to trainer ride to see if I'm improving.

First I have to ask - where do you live that you have a hill that is 30 miles up (or down)? And that a distance like that is considered a "hill"?!?

But to add my 2 cents to the discussion.  If you are using a rear-mounted cyclometer, distance is distance, whether measured on the road or in your living room.  It clearly is a very different workout than riding outside, both because you cannot ever "cheat" by coasting, and because (for me at least), you have to fight harder against the boredom, and the overheating.  So the question you really need to ask yourself is whether you are riding to keep the endurance and pacing up, or to add up miles.

I've had a trainer for years, but this past spring is when I really got serious about using it more than a couple of times in the off season.  I could see results when I got back on the road, even though I only started to ride with it in Feb or March, and then rarely more than 45-60 minutes at a time (usually for however long a DVD episode of Battlestar Gallactica ran.) Because it was a more "pure" workout - i.e. pedaling a steady cadence the whole time - even my hill work was better (at least judging by the fact that my usualy riding partner, who for the last several years would cream me going up hill, only started to catch up on the hills on our last couple of rides this year).

And I remember years ago (in the late 80's), reading about someone who did really well in her races, but because of being a mom with young kids, did all of her training on a trainer and a treadmill; almost none outdoors. 

OK, so if you then want more (or less) resistance, switch gears again.  I don't get what the problem is here.  I can get as much resistance as I want on the trainer by just continuing to switch to a higher gear.  It doesn't really matter what gear you are in, as long as you are getting the resistance that you want, does it? 

It was a philosophical thinking exercise.  30 was an arbitrary number.  The point was a set distance of constant grade, and yes a 30 mile stretch of 5% grade would still be a 'hill'.

The only issue I have here is that 'adding up miles' is pretty worthless.  Let me just throw my bike on the trainer and not even bother engaging the drum,  then ride 50 miles a day.  I would be putting in impressive 350 mile weeks, but is it doing me much good?  It's getting my butt used to the seat, but not much more.

I'm not saying that the trainer is worthless.  I'm saying you can't approach it the same as you approach going outside to ride, and that using time and effort is a much more accurate way of gauging a workout then just how far you go.  It's the least variable combo.