Power difference - indoor Vs outdoor - Page 4

I really hope there is a difference of 40 Watts between indoor and outdoor training. If it's correct, I am already near or above my first goal of a 300W FT.
Unfortunately without a power meter I can't prove it.

Does riding without any wind and a sustainable 300W on the flat equate to an approximate speed one can maintain?

My favorite speed predictor is this one,
http://w3.iac.net/~curta/bp/velocity.../velocity.html

With 300 W you'd be somewhere between 36 km/h (riding on the hoods (btw, what are those hoods??)) to 39 km/h, riding on the drops.

Has anyone compared 5 sec or 1 min power to the trainer on PT

Thanks SW, in that case I'm generating somewhat over 300Watts outside.
Can't tell you the figure because RD might be listening.

The brake lever hoods?

Speed is not a very good predictor of power on the road except on an upgrade. This is because position, wheels, tires and wind affect speed so greatly. These variables can easily represent 50 watts. OTOH, if you can find a consistent grade of ~6%, smooth road and little to no wind, speed can be a very good predictor of power. I haven't compared my actual numbers with the predictions at the above link, but I have a lot of confidence in the underlying algorithms at analyticcycling.com. By contrast, my numbers are not consistent with the calculator at http://www.kreuzotter.de/english/espeed.htm.

it is huge... drop the room temp to about 10-12 degrees celcius and you can raise your TSS huge and as well be able to stay on the trainer way longer as well... and it also reduces the strain you put on your body and ability to recover day to day... a bit of an epiphany for me this winter.

I certainly agree with that. Its been cold and raining ALL week and I've been on the trainer every night so far for at least 90 mins but I also have a HUGE industrial fan (about 1 metre in diameter ) and I've needed to put a t-shirt on over my top for at least 10 - 15 minutes into a workout. Despite the 'boredom' I've held my usual road power figures and felt quite fresh the day after (workouts included 2*L4 sessions)

__________________
Pinarello Paris FP Carbon

Now this post has really made me wonder what my true FTP is. My gym's run by the city hall with no expense spared (they're spending my tax money). There are a lot of old fogeys (like me) training there so the place is like an incubator. I assume you mean your TSS can be increased through an increase in power, not only through an increase in time spent on the trainer.
If DS what you say is true then .......................????
Last Sunday on the century I was riding comfortably at 46/48kmh on the flat, could easily have gone faster - but the question is how much faster? I know RD you don't equate speed on the flat with power, but having the power, must to a certain extent decide what speed you can sustain for any length of time.

I'm off to Alaska to find a gym!

C'mon now, Tyson, sounds like you're spinning us a yarn here? I'll need some details before I can believe that. Like, how long were you comfortably holding that speed, how hard was the tailwind, and when was the last time you checked the settings on your bike computer? What was the total riding time on the century (metric, or 100mi)?

If you could hold that pace (46km/hr - comfortably, or not) for just 25 of the 100 miles, you would have won the Kansas State Cat 1/2 TT Championship last year by over 5 minutes.

I'm not saying it was for any distance. It was for about 10/15 mins till we hit a hill. And of course we were taking turns at the front, but even when I hit the front I didn't feel I was over extending myself. Also as you say, there might have been a tail wind - I have no idea whether there was or wasn't.
The point I was trying to make is that for half a 1x20 (my gym intervals) i.e. a 1x10 in the gym equivalent I was doing the above speed with out stress.
One more point; this was in the first 15 miles of the century so the old legs were still fresh and the adrenalin was flowing like wine. TYSON

I read through many of the posts about this subject and I'd like to shed some light into the mystery of the increased perceived exertion at the same power output on an indoor trainer versus riding outdoors.

It has to be thought of in these principles: [1] Momentum and [2] Pedal Dynamics.

[1] Momentum. First consider the following, when you ride outside and stop pedaling, what happens? Well on a falt road with no wind you will coast for some distance before stopping or until you begin pedaling again. Depending on the speed at which you are traveling in the first place will determine how far you will travel with no additional pedaing. Everyone follow? Try this next time you are riding outdoors. From a standing start, pedal only once as hard as you can and whatever gear you want {remember the gear you used}, then see how far you coast after only one pedal revolution. when you stop, get off the bike and roll the bike back to where you began taking notice to how many times your wheel rolled over and made a complete revolution. The in that same gear from a standing start on your indoor trainer, do the same. It shouldn't be any shock that on a rear wheel stationary trainer, your wheel MIGHT make a full revolution after you stop pedaling. As many have said, this is because of momentum, more specifically angular momentum. It what allows a wheel to remain upright while spinning. The faster you go, the more stable you become [based on material specifications of course]. Bascially the resistance on a trainer is MUCH MORE than you receive outside on the road. Many may argue this point, but bare in mind that the only thing slowing your down on the road is the wind and the your wheel bearings/tires' rolling resistance [on a flat road].

[2] Pedaling Dynamics. Many would love to argue that they have perfected the "spin" and have a zero amount of negative force on their pedal stroke. Well, outdoors many people can consider this, as we all have intertia on our side to allow the pedals to come out from underneith us through the "dead spot" and begin the next pedal stroke with that same leg. Negative pedal force is the application of force with one leg that will negatively affect the momentum of the pedal stroke from the opposing leg. In other words you are pedaling against yourself. Many of you have probably heard of a "spin scan" which can show how much more efficient your right leg is that your left.
What occurs on an indoor trainer [keeping in mind what I said about momentum] is that you change your pedaling dynamics to compensate for the increased resistance throughout the pedal stroke. Everyone tries to mimic the power they produce outside the same way. What happens, you get tired in a shorter amount of time, get frustrated and angry because you can't turn the power. Simply put, you are pedaling against your self. Still think I'm full of it? Try riding at 150 watts and watch your heart rate, first ride the way you always do with your pedals clipped in. Next ride at 150 watts with your feet upclipped and just pedal DOWN, dont try to pull through. You;ll notice that your heart rate will drop. Why is this? You are pedaling and relaxing with each stroke. The same way you do outside with intertia in you favor. You don't see this as much, since you the bike will continue to roll otherwise. You aren't trying to pedal through at the bottom which is causing you to "run into" your opposing legs' pedal stroke. This in turn causes you to lose power and feel like you are riding harder.

So, this begs the question, do I ride at my outdoor power or indoor power. Try this, do a ride outside and do a 10 min TT, as hard as you can, but put some black tape over the power output. Just ride as hard as you can. DO the same thing on the indoor trainer and compare the numbers. The idea is to hide your power output from your eyes until after the effort is over. This way you can't cheat yourself. If you truly ride as hard as you can, your numbers will be lower on the indoor trainer 99 times out of a 100 - remember to give yourself a day of recovery between efforts to assure you are fresh for each one. Make new power ranges based on your indoor numbers, or indoor workouts.

Fans can keep you cool - true. Having a positive attitude before each workout is also a good thing, but these are no performance determinants. Remember the mind will always quit before the body.

Take this post how you will.

Try the attached power equation that I made; it shows each of the components of power.

Attached Files

PE2.zip (4.7 KB, 17 views)

Wow-this post took me a while to get through. Well written, just very detailed.

So let me get this straight: you're arguing that 1. Resistance on a trainer is greater than outdoors (which, 1st of all, isn't always true-I did threshold intervals at 30 mph on my old trainer, while I might go 24 at the time outside-and 2nd of all: doesn't directly impact power output, only the speed at which you go for that power.

and 2:this greater resistance causes a change in pedaling style which reduces power output (well, climbing or riding in a headwind result in greater resistance, yet most people see no power loss during these situations)


Am I reading you write?

So let me get this straight: you're arguing that 1. Resistance on a trainer is greater than outdoors (which, 1st of all, isn't always true-I did threshold intervals at 30 mph on my old trainer, while I might go 24 at the time outside-and 2nd of all: doesn't directly impact power output, only the speed at which you go for that power.

>>>>Yes I am arguing that resistance in higher on a trainer than outside, and it is. Let me explain what resistance is, and how it is effecting this thread. Resistance on the trainer is refering to the load of rolling resistance on the tire. What you are referring to above while comparing 30 to 24 mph during intervals is referring to a generalized meaning of resistance. You have to take into account wind, gravity, rolling resistance and drag. So yeah, you can ride 30 mph which is representing the speed you can spin your wheel on a trainer. It doesn't compare to moving through the atmoshphere and taking the formentioned factors into account.

The resistance on an indoor trainer decreases the wheels' moment of interia. If you still can't grasp this, try this: put your bike on the trainer, with the resistance applied. With your hand on the tire, just try to push the wheel forward with whatever amount of force you want. Notice what happens. Then take just a rear wheel outside to your driveway, or somewhere flat, and with that same amount of force, see how far the wheel will roll before it falls over. That should should make it pretty clear. The wheel will make MORE revolutions outdoors with the same initial power.

and 2:this greater resistance causes a change in pedaling style which reduces power output (well, climbing or riding in a headwind result in greater resistance, yet most people see no power loss during these situations)

>>>>Again, let's look at the types of resistance, and how they are effecting the riders power output. When you are riding uphill or into a headwind, you are increasing your resistance, this is true. But what is being resisted? When you ride on a trainer, the only part of the bike that is being resisted is the wheel. What is being resisted when riding outdoors??? It is the bike, the rider, your shoes, your helmet, and anything else attached to the bike that is moving forward. So when you are riding outside, the added factors of resistance are slowing you as a unit down, but it isn't affecting the rolling resistance of the bike and how you are pedaling. And even still, you are moving forward and have some moment of interia which again, allows the wheel to remain in motion.

And the change in pedaling style is true on a rear wheel wind, magnetic or fluid trainer. If you think it isn't - try a set of rollers, your speed will be higher than on a rear wheel trainer, but this doesn't accuately represent your "Real world" velocity. Also, on rollers you can maintain a closer level of power output compared to outdoors with similar heart rate, since you are actually giving your wheels some angular momentum (more so than on a rear wheel trainer). If all the posts speaking to heat, lack of wind to cool you off, and mental fortitude as the reason for loss of power indoors are correct, then you might see similar effects on rollers. This isn't the case.

What I am trying to get at here, is that the resistance, IS in fact changing the way you pedal on the bike. There is a component of negative force being applied on each or both legs, per pedal stroke AND the way in which your muscles apply power about the pedal stroke is different than outdoors. These combined in some ratio are contributing to the effect of higher perceived exertion at the same power level riding indoors than outdoors.

If someone can offer up a better explanation for this "phenomenon" I'm all ears.

Interesting..

Assuming you are correct, how do you account for the several riders here that experience no loss of power indoors and the odd one (Ric) that can put out more power indoors ?

Also, what are your thoughts on the differential getting smaller with practice ?