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  1. #1
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    Questions about training with power on a trainer

    Hi. I've read that it's better to do the FTP test on the road since it should yield a more accurate (and higher?) max power number than doing it on a trainer. The thing is, for a number of reasons, I'll be doing a lot of training inside. So, a couple of questions:

    What happens then if you do the FTP test on the road and then all your training with that bike/wheel but in a trainer? Do you need to make any corrections, re-calibrations or anything like that if you want to train at a % of the max value measured outside?


    All Powertap rear wheels seem to come with a hub for 10-speed cassettes and my (old) road bike is 9-speed. Can I put a rear wheel w/ a Powertap & 10-speed cassette and adjust the shifters (SRAM 105, I think) to use only 9 of the cogs in the cassette?

    Thanks!

  2. #2
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    You can put your 9 speed cassette on the Powertap. 8, 9 & 10 speed cassettes will all work.

    I do an indoor test for my indoor values and an outdoor test for my outdoor values. Outdoor values are typically ~10% higher for me.

  3. #3
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    Great! Thank you.

  4. #4
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    The reason they say to test outside is that most people don't make the same power indoors at outdoors. IMO, its a combination of lack or airflow indoors and less visual distractions from the pain

  5. #5
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    you can plan on a 6-9% decrease in power on the trainer. for me its the mental toughness to ride indoors (i lack it) so i only do it when i have to, but the one plus side is that if your doing FTP work its very specific and you can get the meat and potatoes of your workout done in a shorter amount of time. no BSing around.

    i agree that the airflow is terrible and you overheat way to fast and i would suspect thats what leads to the decrease in power?

  6. #6
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  7. #7
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    I think the answer for this totally depends on you and your "ability" to ride a trainer.
    First, if you're using two different bikes (some people have a dedicated "trainer" bike), is the fit EXACTLY the same? Also, if your powermeter's zero offset was set outside, you'll need to re-set it for indoor temperatures (then again when you go back outside. Honestly, I set mine every time I ride). If you don't, it's possible that the reading you're seeing is incorrect.
    Other stuff to consider- some people are OK with riding the trainer, but they overheat (likely the case if you're OK for the first 10-20 min of riding, but find yourself fatiguing after that). You can solve this by riding someplace cool, like a garage, using a couple of fans, and drinking ice water. I think most commonly, people find the trainer to be demoralizing, so they just can't convince themselves to lay down the same amount of power. It's relentless, so if you're used to coasting for even just a second or two throughout your intervals, not being able to is tough. Some people get bored- there's not much to focus on other than the feeling of burning and fatigue.
    Personally, I don't see a difference between road and trainer power numbers. I make a playlist of my favorite music, and visualize motivating things.
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  8. #8
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    Thank you all for the interesting (and useful) info. I will be using the same bike/ wheel w/ Powertap for all my training. I tend to tolerate very well heat and humidity (in fact, I've done very well in races where people fall like flies ) but I'm planning on getting a big fan for the summer b/c I agree that performance has to suffer with overheating. As soon as I get my Powertap I'll do two tests (outside and inside) and see what happens. I'm very used to train inside and like the fact you never coast. I sometimes listen to some music but very often is just the trainer noise and me thinking about passing someone at the finish line and that kind of motivating thoughts Interestingly, when I think about those things my HR goes up 5-10 bpm so many times, if want to keep it at certain level, I have to make an effort to fix my mind on something boring

    I didn't know about the need about re-setting the Powertap when changing from outdoors to indoors and vice-versa but I'll do that just to be sure I get the best possible readings.

    Thanks again.

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