Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

"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.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-27-09, 12:32 PM   #1
bdcheung
Carpe Diem
Thread Starter
 
bdcheung's Avatar
 
Join Date: Sep 2006
Location: MABRA
Bikes: 2007 CAAD9; 2014 CAADX; PedalForce CG1
Posts: 13,147
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
SRM offset procedure

Are you supposed to leave the cranks stationary when doing the offset procedure, or continue rotating the cranks backward?
__________________
"When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
ΛΧΑ ΔΞ179 - 15% off your first Hammer Nutrition order!
bdcheung is offline   Reply With Quote
Old 01-27-09, 12:39 PM   #2
djbowen1
Senior Member
 
djbowen1's Avatar
 
Join Date: Jul 2003
Location: NY
Bikes: Cervelo Soliost
Posts: 2,275
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
roate backwards, freewheeling until the number is stable.
djbowen1 is offline   Reply With Quote
Old 01-27-09, 12:47 PM   #3
jrennie
Race to train
 
jrennie's Avatar
 
Join Date: May 2005
Location: suffering on the back
Bikes:
Posts: 3,115
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.
jrennie is offline   Reply With Quote
Old 01-27-09, 12:51 PM   #4
bdcheung
Carpe Diem
Thread Starter
 
bdcheung's Avatar
 
Join Date: Sep 2006
Location: MABRA
Bikes: 2007 CAAD9; 2014 CAADX; PedalForce CG1
Posts: 13,147
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by jrennie View Post
If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.
That's what I thought, and that's what I normally do, but was reading conflicting reports (see post above yours).

So, to be certain, the offset should be done with the cranks stationary and unloaded. Right.
__________________
"When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
ΛΧΑ ΔΞ179 - 15% off your first Hammer Nutrition order!
bdcheung is offline   Reply With Quote
Old 01-27-09, 12:54 PM   #5
OC Roadie
Out of Commission
 
OC Roadie's Avatar
 
Join Date: Mar 2005
Location: SoCal
Bikes: Felt FC, S-Works Roubaix, Epic Comp, Cyfac Proxidium
Posts: 2,272
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by bdcheung View Post
That's what I thought, and that's what I normally do, but was reading conflicting reports (see post above yours).

So, to be certain, the offset should be done with the cranks stationary and unloaded. Right.
This is how I've always done it.
OC Roadie is offline   Reply With Quote
Old 01-27-09, 12:55 PM   #6
bdcheung
Carpe Diem
Thread Starter
 
bdcheung's Avatar
 
Join Date: Sep 2006
Location: MABRA
Bikes: 2007 CAAD9; 2014 CAADX; PedalForce CG1
Posts: 13,147
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
k. you never can be too obsessive about these sorts of things. especially when the Quarq zero-offset procedure can be done while backpedaling.
__________________
"When you are chewing the bars at the business end of a 90 mile road race you really dont care what gear you have hanging from your bike so long as it works."
ΛΧΑ ΔΞ179 - 15% off your first Hammer Nutrition order!
bdcheung is offline   Reply With Quote
Old 01-27-09, 01:01 PM   #7
kudude
slow up hills
 
kudude's Avatar
 
Join Date: Mar 2006
Location: Seattle, WA
Bikes: Giant TCR, Redline CX, Ritchey Breakaway, Spec S-works epic
Posts: 4,931
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by djbowen1 View Post
roate backwards, freewheeling until the number is stable.
yeah, this is wrong. The strain gauge needs to be entirely unloaded. Sucks if you leave in the early morning and come home when it's 20-30 degrees warmer, because you should probably have cleared it a few times. I'm of the sort who doesn't like to get off his bike, but don't really feel like unclipping both feet and fiddling with the powercontrol while coasting along....YMMV
kudude is offline   Reply With Quote
Old 01-27-09, 01:07 PM   #8
merlinextraligh
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Bikes: Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er; Calfee Dragonfly Tandem
Posts: 29,135
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Quote:
Originally Posted by jrennie View Post
If you want to do it while rolling then the cranks need to be still and both feet need to be out. If you are still clipped in or spinning the cranks the offset will rise.
Quote:
Originally Posted by bdcheung View Post
k. you never can be too obsessive about these sorts of things. especially when the Quarq zero-offset procedure can be done while backpedaling.

In zeroing my quarq, I was curious about this. It would seem that spinning the quarq backwards would have the effect jrennie outlines.

However, the quarq cinco instructions are clear that you spin it backwards 4-5 revolutions to zero it.

So I guess the quarq is somehow designed to account for this.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
merlinextraligh is offline   Reply With Quote
Old 01-27-09, 01:23 PM   #9
djbowen1
Senior Member
 
djbowen1's Avatar
 
Join Date: Jul 2003
Location: NY
Bikes: Cervelo Soliost
Posts: 2,275
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
[QUOTE=kudude;8256857]yeah, this is wrong. The strain gauge needs to be entirely unloaded. Sucks if you leave in the early morning and come home when it's 20-30 degrees warmer, because you should probably have cleared it a few times. I'm of the sort who doesn't like to get off his bike, but don't really feel like unclipping both feet and fiddling with the powercontrol while coasting along....YMMV[/QUOTE

Ah yes, i read the manual wrong:

From SRM:
Turn the PowerMeter on by pedalling backwards a few times, and then leave the pedals in a horizontal
position and let go of them. You need to make sure that nothing is touching them or you will end up with
an inaccurate zero offset. With track systems, put forward pressure on the pedals before setting the zero
offset.

Wait until the zero offset stabilises, resting on the same number for a few seconds.

After the zero offset stabilises, press “Set” to store this value for its power calculations.
djbowen1 is offline   Reply With Quote
Old 01-27-09, 01:26 PM   #10
kudude
slow up hills
 
kudude's Avatar
 
Join Date: Mar 2006
Location: Seattle, WA
Bikes: Giant TCR, Redline CX, Ritchey Breakaway, Spec S-works epic
Posts: 4,931
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I tried reading the manual before riding. I just gave up on the description of the powercontrol. I figured I had several hours on the bike to mash buttons until I figured it out. This is to say that their writing on occasion could be clearer.
kudude is offline   Reply With Quote
Old 01-27-09, 01:28 PM   #11
king-tony
Ninja don't wear flipflop
 
king-tony's Avatar
 
Join Date: Aug 2007
Location: NE TN
Bikes: Specialized S-Works Roubaix SL3, BMC TM01...if it every ships
Posts: 1,443
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
There is a zeroing procedure and then a similar procedure for checking your pick-up on the wired version. If you have the wired version you can check by moving the crank back a few degrees at a time and checking the offset. If you get a zero or really low number your sensor is not picking up for the full 360 degrees and will give you inaccurate (usually low) power numbers.
king-tony is offline   Reply With Quote
Old 01-27-09, 01:29 PM   #12
djbowen1
Senior Member
 
djbowen1's Avatar
 
Join Date: Jul 2003
Location: NY
Bikes: Cervelo Soliost
Posts: 2,275
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The manual is a bit much, i use it more as a reference. I havent used my srm in over 6 months, which model did you get?
djbowen1 is offline   Reply With Quote
Old 01-27-09, 03:23 PM   #13
ridethecliche
Village Idiot
 
Join Date: Jan 2007
Location: Bahstaaaaan
Bikes:
Posts: 20,241
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
I've tried doing it both ways and I've ended up with a very similar number both times.

I normally just pedal backwards. I've tried both when using the trainer and the difference was maybe 2-3, which isn't significant.
ridethecliche is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 06:43 PM.