Go Back  Bike Forums > The Racer's Forum > "The 33"-Road Bike Racing
Reload this Page >

Wow, I've gotten fast! Ooops, guess not.

"The 33"-Road Bike Racing We set this forum up for our members to discuss their experiences in either pro or amateur racing, whether they are the big races, or even the small backyard races. Don't forget to update all the members with your own race results.

Wow, I've gotten fast! Ooops, guess not.

Old 11-29-08, 08:41 PM
  #1  
ericm979
Senior Member
Thread Starter
 
ericm979's Avatar
 
Join Date: May 2007
Location: Santa Cruz Mountains
Posts: 6,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Wow, I've gotten fast! Ooops, guess not.

I got my rebuilt Powertap wheel back the other day and did a couple rides on it. On today's ride I went all out on a slightly longer than 20 minute climb. I got a great 20 min power number.... the best I have ever seen by 16 watts. I spent an hour or so thinking how my weight training program must really be effective before reality set in and I checked: the PT wasn't zeroed. It was in fact off by 16 watts. Dammit.

What's wierd is that I never had to zero it before (I have autozero on as recommended).

Is there any way I can fix the two bogus workouts in WKO so they don't mess up my charts and graphs, or should I just delete them?



Edit: Oops, this should have gone in the racing sub-forum. If a mod sees this could you move it please? Thx.
ericm979 is offline  
Old 11-29-08, 11:17 PM
  #2  
umd
Banned
 
umd's Avatar
 
Join Date: Sep 2005
Location: Santa Barbara, CA
Posts: 28,387

Bikes: Specialized Tarmac SL2, Specialized Tarmac SL, Giant TCR Composite, Specialized StumpJumper Expert HT

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
WKO reads in CSV files from the PT right? Just import it into Excel first, subtract 16W from each value, save it as a new CSV file and import that into WKO instead...
umd is offline  
Old 11-30-08, 11:21 AM
  #3  
CrimsonKarter21
Mitcholo
 
CrimsonKarter21's Avatar
 
Join Date: Aug 2006
Location: Oost Vlaanderen in mind, Cleveland in body
Posts: 8,850

Bikes: 2010 Mitcholo w/ Sram Force/Red

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
http://www.midweekclub.ca/powerFAQ.htm#Q46
CrimsonKarter21 is offline  
Old 11-30-08, 04:55 PM
  #4  
recursive
Geosynchronous Falconeer
 
recursive's Avatar
 
Join Date: Sep 2004
Location: Sacramento, CA
Posts: 6,312

Bikes: 2006 Raleigh Rush Hour, Campy Habanero Team Ti, Soma Double Cross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The power can't be off by a constant value.

The torque would be off. The power offset would depend on your cadence.
__________________
Bring the pain.
recursive is offline  
Old 11-30-08, 07:54 PM
  #5  
brianappleby
Senior Member?
 
Join Date: Oct 2005
Location: Denver
Posts: 1,975

Bikes: orbea onix, Cervelo SLC, Specialzed Allez, Cervelo P3 Alu

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Recursive is right.
brianappleby is offline  
Old 11-30-08, 08:04 PM
  #6  
umd
Banned
 
umd's Avatar
 
Join Date: Sep 2005
Location: Santa Barbara, CA
Posts: 28,387

Bikes: Specialized Tarmac SL2, Specialized Tarmac SL, Giant TCR Composite, Specialized StumpJumper Expert HT

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Wouldn't it depend on the speed and not the cadence, since it is measured at the hub and not the crank? Anyway, it would not be difficult to calculate the correct power given the torque and fix it...
umd is offline  
Old 11-30-08, 10:43 PM
  #7  
ericm979
Senior Member
Thread Starter
 
ericm979's Avatar
 
Join Date: May 2007
Location: Santa Cruz Mountains
Posts: 6,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Thanks everyone. I used the process from http://groups.google.com/group/wattage/web/ptnonzero to "fix" it. (which does use the torque and recalculates the power) Now it looks a little low but that's probably more likely to be right.
ericm979 is offline  
Old 11-30-08, 11:32 PM
  #8  
recursive
Geosynchronous Falconeer
 
recursive's Avatar
 
Join Date: Sep 2004
Location: Sacramento, CA
Posts: 6,312

Bikes: 2006 Raleigh Rush Hour, Campy Habanero Team Ti, Soma Double Cross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Originally Posted by umd View Post
Wouldn't it depend on the speed and not the cadence, since it is measured at the hub and not the crank? Anyway, it would not be difficult to calculate the correct power given the torque and fix it...
Yes, you're right. I'm thinking SRM or something for some wrong reason.
__________________
Bring the pain.
recursive is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.