powertap vs carbon wheel

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ophiravina
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Joined: Thu Sep 26, 2013 5:44 pm

by ophiravina

I have an upcoming race in which the course is a 7km timetrial up a hill with 8.8% average gradient.
The race is a first stage out of a four stages tour. if I will ride with my racing rear wheel I will shed about 250g of my bike and the bike will be more aero with 50mm wheels. but if I will ride my power tap wheel (with bontrager rxl rim) I will have a power meter and it can help me mentally and pace me while I'm climbing. the stage will be about 23 minutes so that means that I will ride for the watts of my last 20 minutes test and I'll hope for good. or that I'll ride with my race wheel and pace myself by my feel and maybe heart rate. the second option is less than optimal becouse of the caffein that I will take before the start of the race...
what would you do?
is saving weight and drag is more important on a climb than a power meter?

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bigfatty
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by bigfatty

drag is in effect up to about 7% gradient so it should really not play a part.
loosely, 1 kg = 1 minute loss on a 60 minute effort climbing a 7% hill. so that works out roughly so that makes about a 5 second difference for your effort.
my numbers may not be exact but loosely I imagine they are correct and I am open to corrections.
for me I would go with the power meter and pace yourself.

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spdntrxi
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by spdntrxi

drag difference will be next to nothing
like bigfatty said small penalty for weight

Since it's a fairly good gradient and short distance, I'd up for power personally.
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MattSoutherden
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by MattSoutherden

For a 10 miler, I usually ride to a power target for the first 10 minutes, then see how my legs are, and where my HR is at, and see if I need to make any adjustments over the next 5 minutes. If I feel good and/or my HR is below threshold I will pick it up a bit. Then with 5 minutes to go, just give it what's left.

For your stage, it will be about the balance between finishing with an empty tank, and ensuring you don't slow too much at the end, as dying in the last 500m of an uphill TT can cost buckets of time. How well do you know the climb?
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Rick
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by Rick

Just my take:
I would use the PM, since it is a negligible weight difference, but only use it for about the first 1/3 of the climb, and use it to set upper limits on power and Heart rate. By that point you should know how you feel, so just go as hard as you feel you can go from then on out and refuse to look at the numbers or even turn them off.
Why ?

If you are having a good day, you don't want to limit yourself to numbers that are lower than you can really produce.

If you are having a bad day, you don't want to strive for some number that you will not be able to produce and cause a "blow-up".

Also: be really conservative with the caffeine. It actually hurts me on efforts less than about 2 hrs, because my heart races at a higher level and I am afraid to push as hard. After 2 hrs it keeps me "alert" so I can concentrate on putting out "max" wattage.

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otoman
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by otoman

sell the power tap wheel, use that money to buy a Stages power meter. Crank based power is great and completely eliminates this exact question of yours. It's nice having your cake and eating it too!
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ophiravina
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by ophiravina

bigfatty wrote:drag is in effect up to about 7% gradient so it should really not play a part.
loosely, 1 kg = 1 minute loss on a 60 minute effort climbing a 7% hill. so that works out roughly so that makes about a 5 second difference for your effort.
my numbers may not be exact but loosely I imagine they are correct and I am open to corrections.
for me I would go with the power meter and pace yourself.

wow,thank you very much for the numbers, this is very helpful! :thumbup:

MattSoutherden wrote:For a 10 miler, I usually ride to a power target for the first 10 minutes, then see how my legs are, and where my HR is at, and see if I need to make any adjustments over the next 5 minutes. If I feel good and/or my HR is below threshold I will pick it up a bit. Then with 5 minutes to go, just give it what's left.

For your stage, it will be about the balance between finishing with an empty tank, and ensuring you don't slow too much at the end, as dying in the last 500m of an uphill TT can cost buckets of time. How well do you know the climb?

thank you for the tip, I rode this climb for the first time two days ago and I wont get another chance to ride it, becouse it is on the other side of the country :oops: . you are right about saving energy for the end of the climb, the last kilometer has some gravel sections that made me ride at 60 rpm\450 watt on my 39\28 gear :x (a compact would be the best for this stage, but the only compact crankset that I have at the moment is 172.5mm crankarms and it is too short for me)
Rick wrote:Just my take:
I would use the PM, since it is a negligible weight difference, but only use it for about the first 1/3 of the climb, and use it to set upper limits on power and Heart rate. By that point you should know how you feel, so just go as hard as you feel you can go from then on out and refuse to look at the numbers or even turn them off.
Why ?

If you are having a good day, you don't want to limit yourself to numbers that are lower than you can really produce.

If you are having a bad day, you don't want to strive for some number that you will not be able to produce and cause a "blow-up".

Also: be really conservative with the caffeine. It actually hurts me on efforts less than about 2 hrs, because my heart races at a higher level and I am afraid to push as hard. After 2 hrs it keeps me "alert" so I can concentrate on putting out "max" wattage.

thank you for the tips :D

I will ride with the power meter, it is the smartest decision for this race :beerchug:

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