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does this sound like my power meter is way off
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Here's the old-style math "story problem":

2:20 second climb, .36 miles, 151 ft elevation gain, total combined weight of bike, rider and kit is about 185 lbs.

Does 349 watts seem about right, or on the high side?

The complicating factor is it's an MTB with knobby tires so coefficient of rolling resistance might not be the same for a road bike.

I tried comparing to other strava users but you never know how much they weigh.
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Re: does this sound like my power meter is way off [devolikewhoa83] [ In reply to ]
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Trying to convert that to metric in my brain and put it in some calculators, in which case the error could go up a fair bit, but that certainly sounds about right for that climb. Presuming you are talking average power as well not NP?
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Re: does this sound like my power meter is way off [devolikewhoa83] [ In reply to ]
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Go to https://www.bestbikesplit.com/ . You can put in your numbers and see if you get that time for that power.

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Re: does this sound like my power meter is way off [Amnesia] [ In reply to ]
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Amnesia wrote:
Trying to convert that to metric in my brain and put it in some calculators, in which case the error could go up a fair bit, but that certainly sounds about right for that climb. Presuming you are talking average power as well not NP?
Ha!
The first thing I thought reading the OP was how incongruous the watt seems in the company of all those archaic units of measure. Shouldn't power be given in horsepower in this context. SI units please, but if you must use US customary, don't mix and match....
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Re: does this sound like my power meter is way off [Titanflexr] [ In reply to ]
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Titanflexr wrote:
Go to https://www.bestbikesplit.com/ . You can put in your numbers and see if you get that time for that power.

It was only just over a 2 min effort...I don't think you can do that on bestbikesplit as you need to have the entire course already loaded into their system and then potentially select a segment from it?
Agree with the other post as well....keep it in watts/kg, meters and %grade.....far easier to have it all as metric!
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Re: does this sound like my power meter is way off [Amnesia] [ In reply to ]
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bikecalculator.net might be more useful.
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Re: does this sound like my power meter is way off [Amnesia] [ In reply to ]
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Amnesia wrote:
Trying to convert that to metric in my brain and put it in some calculators, in which case the error could go up a fair bit, but that certainly sounds about right for that climb. Presuming you are talking average power as well not NP?

in case you use Google Chrome, there's a pretty cool add-on that does the conversion directly on the text.
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Re: does this sound like my power meter is way off [devolikewhoa83] [ In reply to ]
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devolikewhoa83 wrote:
Here's the old-style math "story problem":
2:20 second climb, .36 miles, 151 ft elevation gain, total combined weight of bike, rider and kit is about 185 lbs.

Does 349 watts seem about right, or on the high side?

The complicating factor is it's an MTB with knobby tires so coefficient of rolling resistance might not be the same for a road bike.

I tried comparing to other strava users but you never know how much they weigh.

for elevation gain 46m (151ft) in 140 secs at 84kg (185lbs) requires 270w
for rolling resistance, 579meters (.36miles) in 140sec at .005 crr requires 17w for crr (feel freed to add 25%,75%...)
At CDA of .40, no wind at constant speed, requires 17w for overcoming aero...

270+17+17 = 304w.

Depends on your starting and ending speed, may be some watts required for acceleration

I didn't triple check and I only had 1/2 coffee this morning so I apologize in advance for errors :-)
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Re: does this sound like my power meter is way off [devolikewhoa83] [ In reply to ]
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It's not uncommon for me to put out power in the mid 300's while climbing on the mountain bike and I'm only 143 lbs.

For 20-40 second climbs it's not uncommon for me to be in the upper 300's.
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Re: does this sound like my power meter is way off [marcag] [ In reply to ]
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marcag wrote:
devolikewhoa83 wrote:
Here's the old-style math "story problem":
2:20 second climb, .36 miles, 151 ft elevation gain, total combined weight of bike, rider and kit is about 185 lbs.

Does 349 watts seem about right, or on the high side?

The complicating factor is it's an MTB with knobby tires so coefficient of rolling resistance might not be the same for a road bike.

I tried comparing to other strava users but you never know how much they weigh.


for elevation gain 46m (151ft) in 140 secs at 84kg (185lbs) requires 270w
for rolling resistance, 579meters (.36miles) in 140sec at .005 crr requires 17w for crr (feel freed to add 25%,75%...)
At CDA of .40, no wind at constant speed, requires 17w for overcoming aero...

270+17+17 = 304w.

Depends on your starting and ending speed, may be some watts required for acceleration

I didn't triple check and I only had 1/2 coffee this morning so I apologize in advance for errors :-)

This is what I go too for climbing and aero power. Your calculation also looks reasonable for rolling resistance, but as you say who knows what crr is -- could be double especially if the climb wasn't on road.

Anyhow, OP can count on the base figure 270 W minimum from overcoming gravity, rolling and aero numbers are much more fudgable. Slightly bigger Cda + slight headwind + rough terrain + drivetrain loss seems like 349 W could be possible.
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Re: does this sound like my power meter is way off [twcronin] [ In reply to ]
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Thanks everybody. I wanted to just get a sanity check about whether it's waaayyyy off before trying to do a deeper dive into the accuracy. I tried using some calcualtors but i wasn't sure how to modify them to account for the extra rolling resistance of my 2.35 Magic Mary's on the XC bike :)

So, thanks for bringing the hive mind to bear.

and lol about the measurements, I feel the same way when trying to read a british recipe. It'll be like "add in 3 grams of chopped green peppers".
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