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2015-01-21 8:39 PM
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Subject: RE: SBR "U"
Originally posted by GoFaster

Originally posted by ChrisM
Originally posted by axteraa

Originally posted by ratherbeswimming

Aerocamp is back: https://a3hdcamps.wordpress.com/aerocamp-3-0/

This one honestly one of the most fun and educational experiences I've ever had on a bicycle.

LA Velodrome Feb 28 - March 1, coaches Heath Dotson and Brian Stover (who answered my questions long after camp ended - even helped me track down the best parts for my bike), data by Alphamantis, option for a bike fit by Jim Manton, and a chance to try out your gear - and other gear, even gear not on the market yet - and find your most aero set-up.

I'm not affiliated, just a happy customer. 

Just figured I'd pass the info along.

I'm in the area two weeks too early!  I am getting fit by Jim while I'm there though.  

Would love to do it, especially as its 20 minutes from home, but can't justify the expense for where I am as a triathlete. If I were minutes from kona, etc, different story

Looking at the cost though, in comparison to say wind tunnel testing, it seems very reasonably priced.  I hadn't realized the technology company was Canadian - keeps me hoping they put it in the local velodrome.  When I rode last weekend we were told that by May the Pan Am Games take over until almost September and everyone else is kicked out, so I reckon if anything like this does come to town it's not going to be for quite a while.

May be reasonable as compared to a wind tunnel (for me, that's like saying the new jag isn't that expensive when compared with the new mercedes. when I drive a ford.....) but I still cannot come close to justifying $700 to gain enough watts to go from 45th AG to 38th....I can afford it, just don't think it's a valid ROI for me

Edited by ChrisM 2015-01-21 8:41 PM


2015-01-21 8:56 PM
in reply to: brigby1

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Subject: RE: SBR "U"

Originally posted by brigby1

Originally posted by mcmanusclan5

Originally posted by Asalzwed

Originally posted by mcmanusclan5

Originally posted by Asalzwed

Originally posted by mcmanusclan5

Ran today.  Went at a "tempo gait" (which turns out to now be closer to my 10k pace - maybe even a little faster than that - given the HR I hit... sigh) and actually felt much better on the injuries than forcing myself to go slowly.  Achilles is no worse, knee is actually still feeling better and hammy just played along for once.

I have always enjoyed running at tempo or faster.  I wonder if, depending on injury type, that kind of smooth speed (not speed work, mind you - just smoothly fast-ish) is actually good?

Or, I could be setting myself up for a year of not running.    Still have a sore achilles, but with no speed work or hills on this route, it felt and feels pretty ok and certainly no worse.

I was just truly happy to be running again (and it didn't hurt that it was 76, sunny and dry!!!!). 

Matt

Tempo gait? Hahaha! 

So on one hand yes, your form is likely much better when running faster. That is why strides are such a huge component of many run plans. Also, many, many coaches point at sprinters when talking about form. 

But I refuse to say the solution is doing all your running at that speed. I believe this is an opportunity to try and always run with good form, not just when you are running fast. And one way to work on this is through things like strides and drills. 

Hmmm...  Not sure what was funny in that one (unless you actually saw me running).    Certainly wasn't intended as a joke - just trying to describe what I was shooting for from a stride/mechanics standpoint. You don't feel a difference in your gate for runs at different paces?

I'm not at all saying I plan to run EVERY run fast or even at a moderate pace - or that I'm planning anything based on this run... just asking a question.  This was a "fast not hard" stride - perhaps a bit slower than what the first half of a HM would be/feel like (but only done for a couple miles).  Certainly wasn't suggesting that the solution to injury rehab is to run every run at that pace.

Let me try again, as perhaps the question will be more clear this way:  is running slowly until you're at 100% the right approach in coming back after a tweak (with consideration to the nature of the tweak, of course)? 

I suspect not (cue someone to respond with the "lots/mostly slow/sometimes fast" axiom), although I don't know.  Hence...

Thoughts?

Matt

Ah nah, I am just teasing really.

I just find that I run how I run. Certainly things seem to get closer to "perfect" when we run faster but I don't think there should be such a wide variance in your gait when you run slowly and when you run fast. But I think many, many people feel, and experience what you do. So I apologize if I was minimizing your thoughts. I do get what you are saying.

I can't tell you how many people think I am crazy when I run slowly, stating that they could "never run that slow" because it's uncomfortable. And maybe that is exactly the issue, right? 

All that being said, I can't really answer your question. I think it's too personal.

I've not had a running specific injury but my experience coming back from a break is to do all easy running for a block of time before I ever add speed. And I do this mainly because I never build up volume at the same time as adding in quality (or "speed.")

But I also feel that it's often as simple as: if it hurts, don't do it and if it feels good, keep with it. You just have to be really honest with yourself. I could see something like shorter easy runs with strides, on a soft surface (with rest in between) could really work for you.

No worries!  Figured as much...  Just trying to find the best way forward, as I've now had a few injuries that were running related and don't have the healing thing down pat just yet!

The first two were clearly from not recovering sufficiently after a hard race (learned that lesson... Finally!).  But this one was from modifying my gait.  So, going back to "just running the way I run" was something I wanted to try.  Guess we'll see, but I'm sprinkling some caution in here, too!

Matt

Matt, I've felt less difference between my faster & easier running after doing fast stuff more frequently and by getting in a more dynamic warm-up before every run.

I think this is a great point.  I certainly can feel my legs come back under me (even at a silly slow pace) a couple miles into a long run.  Same is true after a good warmup before track work.  I think you and Rusty might be convincing me (in different ways and without trying) that I am now old enough (not OLD, mind you) to be more mindful about getting a warmup in.  

The more frequent fast stuff also resonates.  This time last year I was doing a lot more interval, track and hill work at speed and really felt my overall form was consistently better - even on recovery runs.  I have a couple months of base work to do before getting back to the track in any serious way, at this point though!

I do miss the track...

Matt

2015-01-21 9:20 PM
in reply to: ChrisM

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Subject: RE: SBR "U"

Originally posted by ChrisM
Originally posted by GoFaster

Originally posted by ChrisM
Originally posted by axteraa

Originally posted by ratherbeswimming

Aerocamp is back: https://a3hdcamps.wordpress.com/aerocamp-3-0/

This one honestly one of the most fun and educational experiences I've ever had on a bicycle.

LA Velodrome Feb 28 - March 1, coaches Heath Dotson and Brian Stover (who answered my questions long after camp ended - even helped me track down the best parts for my bike), data by Alphamantis, option for a bike fit by Jim Manton, and a chance to try out your gear - and other gear, even gear not on the market yet - and find your most aero set-up.

I'm not affiliated, just a happy customer. 

Just figured I'd pass the info along.

I'm in the area two weeks too early!  I am getting fit by Jim while I'm there though.  

Would love to do it, especially as its 20 minutes from home, but can't justify the expense for where I am as a triathlete. If I were minutes from kona, etc, different story

Looking at the cost though, in comparison to say wind tunnel testing, it seems very reasonably priced.  I hadn't realized the technology company was Canadian - keeps me hoping they put it in the local velodrome.  When I rode last weekend we were told that by May the Pan Am Games take over until almost September and everyone else is kicked out, so I reckon if anything like this does come to town it's not going to be for quite a while.

May be reasonable as compared to a wind tunnel (for me, that's like saying the new jag isn't that expensive when compared with the new mercedes. when I drive a ford.....) but I still cannot come close to justifying $700 to gain enough watts to go from 45th AG to 38th....I can afford it, just don't think it's a valid ROI for me

But that was $700 for 3 days - if there was a single day thing maybe it's much more reasonably priced.  Like the cost of a new helmet, type price?

2015-01-22 5:32 AM
in reply to: GoFaster

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Subject: RE: SBR "U"
Okay, printed out the mentor program trainer workouts. They do look a bit meatier than Jorge's stuff, with longer threshold workouts and some "sweet spot" stuff. Really, really wish I had a power meter that would take all the guesswork or calculations out of it! I actually trained for my fastest Oly ride (1:17) and first HIM entirely on the gym stationary using the watt meter except for some of my long rides, even last spring was doing 1-2 rides a week there. I liked the clear structure of the workouts and immediate power feedback, but it seems silly to go ride in the gym while a perfectly good Cervelo and trainer sit at home. It's also a lot more convenient to get in my rides at home early AM than head to the gym after work. I can use HR to some extent, especially for longer efforts, since I'm really familiar with what HR correlates with various % of max.

I noticed that for the first eight weeks they are pretty much a mix of VO2 max, threshold, and sweet spot stuff, and long ride doesn't come in there till Week 9. Clearly this won't work in my case as I'd not have many long rides before the HIM. Better to focus on threshold and sweet spot, since it's closer to what I'll be racing, or start with some max work? If it matters, the ratio of my 5-minute test to 20 minute test was 1.125 (from test at the gym last year, doubt it has changed much) so kind of fall into the middle range. During the fall run focus I was riding twice a week, alternating a single max or threshold trainer workout of 50-70 minutes during the work week and then a longer ride of 1:30 to 2:30 with some "sweet spot" type effort on the weekends. Since then have just geen doing easy to moderate riding due to taper, race, travel, illness etc. until this week
2015-01-22 8:25 AM
in reply to: Hot Runner

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Subject: RE: SBR "U"

So, I did the 20 min power test this morning.  Result was 311w which I'm very happy with.

Now the problem - I ran my old PT (or maybe Tab's, I'm not sure...) at the same time and it only reported 294w.    I was pretty surprised when I saw that as during the first 3-4 minutes of the workout I had the two computers side by side and they were right on - 30s power was within 1 watt the whole time.  At that point I just put the computer reading the PT to the side and didn't look at it again until near the end of my cool down.  At that point I noticed the 30s power was about 8w lower on the PT.  I coasted to do an auto zero and they were back to agreeing with 1-2w.

So, I *think* I have a temperature drift problem.  I broke the workout down into chunks and got the following

Broken down as P2Max / PT 
First 5 mins - 157 / 155 (coasted to auto zero both PMs)
Next 6:45 - 173 / 171 (so far so good, auto zeroed again)

At this point, I opened two windows directly beside me (outside temp -7C)

Next 10 mins - 182 / 177 (auto zeroed again)
Next 1:30 - 175 / 168
For the 20 min test broken down by 5 min chunks I got
299 / 288
307 / 291
316 / 297
321 / 299
Next 8 mins - 143 / 136 (noticed the discrepancy and auto zeroed)
Last 1:30 - 158 / 156 (back to agreement after the auto zero).

So, it seems like when I opened the windows (ie. blast chiller) the two started to drift apart. The P2Max is *supposed* to have active temperature compensation so I'd like to believe that is the one that is most right but who knows how well that really works?? The PT certainly doesn't have any temperature compensation built in.

Thoughts?  

2015-01-22 8:48 AM
in reply to: axteraa

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Subject: RE: SBR "U"
Semiconductors lose their thermal properties over time. Not just semiconductors but diodes, resistors and all the other electronic components. So over time tempture ranges go up over sign specification causing failures. I can go into depth about this from my years of geekiness. Well more of just experience with over clocking CPU's.


2015-01-22 8:50 AM
in reply to: BrotherTri

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Subject: RE: SBR "U"

Right, I totally get that the drift happens and it makes sense.  My question is more "which is right?" (or less wrong)  

2015-01-22 8:51 AM
in reply to: axteraa

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Subject: RE: SBR "U"
Btw great job on the 20'. Did you input your 5' and 20' into GC? What was the FTP? I do my 20' test tomorrow.
2015-01-22 8:54 AM
in reply to: axteraa

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Subject: RE: SBR "U"
Originally posted by axteraa

So, I did the 20 min power test this morning.  Result was 311w which I'm very happy with.

Now the problem - I ran my old PT (or maybe Tab's, I'm not sure...) at the same time and it only reported 294w.    I was pretty surprised when I saw that as during the first 3-4 minutes of the workout I had the two computers side by side and they were right on - 30s power was within 1 watt the whole time.  At that point I just put the computer reading the PT to the side and didn't look at it again until near the end of my cool down.  At that point I noticed the 30s power was about 8w lower on the PT.  I coasted to do an auto zero and they were back to agreeing with 1-2w.

So, I *think* I have a temperature drift problem.  I broke the workout down into chunks and got the following

Broken down as P2Max / PT 
First 5 mins - 157 / 155 (coasted to auto zero both PMs)
Next 6:45 - 173 / 171 (so far so good, auto zeroed again)

At this point, I opened two windows directly beside me (outside temp -7C)

Next 10 mins - 182 / 177 (auto zeroed again)
Next 1:30 - 175 / 168
For the 20 min test broken down by 5 min chunks I got
299 / 288
307 / 291
316 / 297
321 / 299
Next 8 mins - 143 / 136 (noticed the discrepancy and auto zeroed)
Last 1:30 - 158 / 156 (back to agreement after the auto zero).

So, it seems like when I opened the windows (ie. blast chiller) the two started to drift apart. The P2Max is *supposed* to have active temperature compensation so I'd like to believe that is the one that is most right but who knows how well that really works?? The PT certainly doesn't have any temperature compensation built in.

Thoughts?  




Why do I feel I instigated this check :-). I think you should redo the test with the doors closed :-)

You never zeroed the P2max, only the PT, correct ?



2015-01-22 9:03 AM
in reply to: marcag

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Subject: RE: SBR "U"

Originally posted by marcag Why do I feel I instigated this check :-). I think you should redo the test with the doors closed :-) You never zeroed the P2max, only the PT, correct ?

I was using some of your french swear words this morning.  

Both were zeroed at the same time.  It's just a coast to trigger both of them (not a back pedal like a Quarq)

2015-01-22 9:04 AM
in reply to: BrotherTri

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Subject: RE: SBR "U"

Originally posted by BrotherTri Btw great job on the 20'. Did you input your 5' and 20' into GC? What was the FTP? I do my 20' test tomorrow.

CP / FTP comes out as 294w which would be about a 10w increase over the last one I did.



2015-01-22 9:22 AM
in reply to: axteraa

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Subject: RE: SBR "U"
Originally posted by axteraa

Right, I totally get that the drift happens and it makes sense.  My question is more "which is right?" (or less wrong)  

Arend, I think it may actually be a problem with the Fetzer Valve on the PT, and probably caused by humidity, not temperature. So it is probably not an electronics problem, instead it is in all likelihood an issue with the ball bearings. Because, well, as you know it's all ball bearings nowadays. Now you repair that Fetzer valve with some 3-in-1 oil and some gauze pads. And you are also going to need about ten quarts of anti-freeze, preferably Prestone. No, no, wait make that Quaker State.

Oh, and no matter which outcome is correct, that looks like one well-ridden test - nice!

2015-01-22 9:30 AM
in reply to: Hot Runner

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Subject: RE: SBR "U"
Hey Karen - just wanted to jump in and offer a belated welcome to the group as well. I have always enjoyed your comments and questions in TT. I have a couple of thoughts about your initial post - will follow up with you when I am not on the road and typing on the phone. I wound up with a couple of meetings changed to conference calls that I could do from the car, so I just snuck out of work and am headed up to the mountains to ride. Woot!
2015-01-22 9:30 AM
in reply to: mcmanusclan5

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Subject: RE: SBR "U"

Originally posted by mcmanusclan5

Originally posted by brigby1

Matt, I've felt less difference between my faster & easier running after doing fast stuff more frequently and by getting in a more dynamic warm-up before every run.

I think this is a great point.  I certainly can feel my legs come back under me (even at a silly slow pace) a couple miles into a long run.  Same is true after a good warmup before track work.  I think you and Rusty might be convincing me (in different ways and without trying) that I am now old enough (not OLD, mind you) to be more mindful about getting a warmup in.  

The more frequent fast stuff also resonates.  This time last year I was doing a lot more interval, track and hill work at speed and really felt my overall form was consistently better - even on recovery runs.  I have a couple months of base work to do before getting back to the track in any serious way, at this point though!

I do miss the track...

Matt

Er, I'm like several age groups younger than you are?

2015-01-22 9:47 AM
in reply to: Hot Runner

Master
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Subject: RE: SBR "U"

Originally posted by Hot Runner  I noticed that for the first eight weeks they are pretty much a mix of VO2 max, threshold, and sweet spot stuff, and long ride doesn't come in there till Week 9. Clearly this won't work in my case as I'd not have many long rides before the HIM. Better to focus on threshold and sweet spot, since it's closer to what I'll be racing, or start with some max work? If it matters, the ratio of my 5-minute test to 20 minute test was 1.125 (from test at the gym last year, doubt it has changed much) so kind of fall into the middle range. During the fall run focus I was riding twice a week, alternating a single max or threshold trainer workout of 50-70 minutes during the work week and then a longer ride of 1:30 to 2:30 with some "sweet spot" type effort on the weekends. Since then have just geen doing easy to moderate riding due to taper, race, travel, illness etc. until this week

What do you know about your current fitness? A year is a long enough time that your profile could have change notably from then. A plan is not about training at what you'll be racing at, but doing what you need to improve your race performance. You won't race at VO2 max, but making sure that is up higher to start will help in developing the ability to sustain a power output for a longer time. The ability to sustain tends to be a lot about putting in time. That time will be about the same regardless of what you do for workouts (age groupers are mostly time limited), so the actual output at race time will be better if you're taking a percentage of a higher max number to start with. Without solid data to show a rather strong VO2 max I think you'd be fine following the plan. If you retest for current ability and find otherwise, then possibly rethink the plan (or if the last test was much more recent than I've understood it to be).

2015-01-22 9:59 AM
in reply to: marcag

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Subject: RE: SBR "U"

Originally posted by marcag
Originally posted by axteraa

So, I did the 20 min power test this morning.  Result was 311w which I'm very happy with.

Now the problem - I ran my old PT (or maybe Tab's, I'm not sure...) at the same time and it only reported 294w.    I was pretty surprised when I saw that as during the first 3-4 minutes of the workout I had the two computers side by side and they were right on - 30s power was within 1 watt the whole time.  At that point I just put the computer reading the PT to the side and didn't look at it again until near the end of my cool down.  At that point I noticed the 30s power was about 8w lower on the PT.  I coasted to do an auto zero and they were back to agreeing with 1-2w.

So, I *think* I have a temperature drift problem.  I broke the workout down into chunks and got the following

Broken down as P2Max / PT 
First 5 mins - 157 / 155 (coasted to auto zero both PMs)
Next 6:45 - 173 / 171 (so far so good, auto zeroed again)

At this point, I opened two windows directly beside me (outside temp -7C)

Next 10 mins - 182 / 177 (auto zeroed again)
Next 1:30 - 175 / 168
For the 20 min test broken down by 5 min chunks I got
299 / 288
307 / 291
316 / 297
321 / 299
Next 8 mins - 143 / 136 (noticed the discrepancy and auto zeroed)
Last 1:30 - 158 / 156 (back to agreement after the auto zero).

So, it seems like when I opened the windows (ie. blast chiller) the two started to drift apart. The P2Max is *supposed* to have active temperature compensation so I'd like to believe that is the one that is most right but who knows how well that really works?? The PT certainly doesn't have any temperature compensation built in.

Thoughts?  

Why do I feel I instigated this check :-). I think you should redo the test with the doors closed :-) You never zeroed the P2max, only the PT, correct ?

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?



2015-01-22 10:01 AM
in reply to: GoFaster

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Subject: RE: SBR "U"

Originally posted by GoFaster

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?

Every time you coast for a few seconds, the PT will do an auto zero (same as the calibrate at the beginning).  When you ride outside, this usually happens on a regular basis.  On the trainer, not so much.

2015-01-22 10:40 AM
in reply to: brigby1

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Subject: RE: SBR "U"

Originally posted by brigby1

Originally posted by mcmanusclan5

Originally posted by brigby1

Matt, I've felt less difference between my faster & easier running after doing fast stuff more frequently and by getting in a more dynamic warm-up before every run.

I think this is a great point.  I certainly can feel my legs come back under me (even at a silly slow pace) a couple miles into a long run.  Same is true after a good warmup before track work.  I think you and Rusty might be convincing me (in different ways and without trying) that I am now old enough (not OLD, mind you) to be more mindful about getting a warmup in.  

The more frequent fast stuff also resonates.  This time last year I was doing a lot more interval, track and hill work at speed and really felt my overall form was consistently better - even on recovery runs.  I have a couple months of base work to do before getting back to the track in any serious way, at this point though!

I do miss the track...

Matt

Er, I'm like several age groups younger than you are?

LOL!  You definitely are!

Just saying that I now can appreciate the effect of a good warm up a lot more than when I was less chronologically challenged.  The warmup is always, and has always been, a good idea - it's just that it now seems to matter more to my creaky bones.

So, you're not older, just smarter!

Matt

2015-01-22 10:43 AM
in reply to: axteraa

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Austin, Texas
Subject: RE: SBR "U"

Originally posted by axteraa

Originally posted by GoFaster

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?

Every time you coast for a few seconds, the PT will do an auto zero (same as the calibrate at the beginning).  When you ride outside, this usually happens on a regular basis.  On the trainer, not so much.

Side question.  Do folks with Quargs calibrate mid rides outside (or even on the trainer) routinely to keep the data solid?  I do it at the beginning but rarely during a ride...

With temperature changes over the course of a ride, I wonder if there's much drift or so minimal it's not an issue intra-ride.  Sorry if this was clear to others in the above...  Wondering about degree of change over such a short time frame rather than over the life of the equipment.

Thanks

Matt

2015-01-22 11:05 AM
in reply to: mcmanusclan5

Master
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Northern IL
Subject: RE: SBR "U"

Originally posted by mcmanusclan5

Originally posted by axteraa

Originally posted by GoFaster

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?

Every time you coast for a few seconds, the PT will do an auto zero (same as the calibrate at the beginning).  When you ride outside, this usually happens on a regular basis.  On the trainer, not so much.

Side question.  Do folks with Quargs calibrate mid rides outside (or even on the trainer) routinely to keep the data solid?  I do it at the beginning but rarely during a ride...

With temperature changes over the course of a ride, I wonder if there's much drift or so minimal it's not an issue intra-ride.  Sorry if this was clear to others in the above...  Wondering about degree of change over such a short time frame rather than over the life of the equipment.

Thanks

Matt

Supposed to, but I really haven't. Just before the ride.

2015-01-22 11:19 AM
in reply to: mcmanusclan5

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Master
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Subject: RE: SBR "U"
Originally posted by mcmanusclan5

Originally posted by axteraa

Originally posted by GoFaster

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?

Every time you coast for a few seconds, the PT will do an auto zero (same as the calibrate at the beginning).  When you ride outside, this usually happens on a regular basis.  On the trainer, not so much.

Side question.  Do folks with Quargs calibrate mid rides outside (or even on the trainer) routinely to keep the data solid?  I do it at the beginning but rarely during a ride...

With temperature changes over the course of a ride, I wonder if there's much drift or so minimal it's not an issue intra-ride.  Sorry if this was clear to others in the above...  Wondering about degree of change over such a short time frame rather than over the life of the equipment.

Thanks

Matt

I do, particularly on long rides outside I can see some significant drift. If I understand it correctly though in the newest firmware update they changed it so that it does it automatically when you coast, but I still do it out of habit. So before when the Quarq got a cadence reading (from pedaling backwards) and a zero power reading it reset the offset (calibrating is actually a different thing, but Garmin has conflated that). This similar to power tap, when it gets a zero power meter and an RPM from the wheel, it rests the offset. With the Quarq it now resets the offset when it gets a zero power reading and no cadence. I like it better the other way and I think it still works as well. On my Garmin vectors you also pedal backwards to reset the offset - the good thing about the vectors is that if you are using a Garmin head unit it gives you a notice that it is reset. BUT you have to be careful when you pedal backwards when in your largest gear; the clearance between the chain and the plug that goes in to the spindle is very close and you can shear it off with the chain. Don't ask me how I know this....



2015-01-22 11:26 AM
in reply to: TankBoy

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Subject: RE: SBR "U"

Originally posted by TankBoy

I do, particularly on long rides outside I can see some significant drift. If I understand it correctly though in the newest firmware update they changed it so that it does it automatically when you coast, but I still do it out of habit. So before when the Quarq got a cadence reading (from pedaling backwards) and a zero power reading it reset the offset (calibrating is actually a different thing, but Garmin has conflated that). This similar to power tap, when it gets a zero power meter and an RPM from the wheel, it rests the offset. With the Quarq it now resets the offset when it gets a zero power reading and no cadence. I like it better the other way and I think it still works as well. On my Garmin vectors you also pedal backwards to reset the offset - the good thing about the vectors is that if you are using a Garmin head unit it gives you a notice that it is reset. BUT you have to be careful when you pedal backwards when in your largest gear; the clearance between the chain and the plug that goes in to the spindle is very close and you can shear it off with the chain. Don't ask me how I know this....

I wish Garmin would give that notice with other PMs too.  I also wish there was a shortcut to get to the manual zero (not saying Calibrate) page rather than having to go through 8 menu options.

2015-01-22 11:38 AM
in reply to: axteraa

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Subject: RE: SBR "U"
Originally posted by axteraa

Originally posted by marcag Why do I feel I instigated this check :-). I think you should redo the test with the doors closed :-) You never zeroed the P2max, only the PT, correct ?

I was using some of your french swear words this morning.  

Both were zeroed at the same time.  It's just a coast to trigger both of them (not a back pedal like a Quarq)




hmmmmmm. If I were to bet I would say it's an auto-zero issue and not a temperature drift. Yes, opening the windows cools things a bit but you didn't drop the temperature of the room dramatically.

I know for a fact that I had auto-zero problems with my powertap in the past. It probably doesn't appear on an outdoor ride because it auto zeros frequently so you may have an interval of time with bad data but it comes back. I noticed it when riding the PT on the computrainer. They would be almost aligned, I would coast and they wouldn't be aligned. I would coast and they would come back aligned.

I would try doing a my VO2 workouts with the 2 side by side, with no autozeroing to see if they drift or not.

stupid power meters.....

2015-01-22 11:47 AM
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Subject: RE: SBR "U"
Originally posted by TankBoy

Originally posted by mcmanusclan5

Originally posted by axteraa

Originally posted by GoFaster

Getting confused - auto zero the PT?  I've never heard of this one.  I just calibrate before every ride, am I missing something?

Every time you coast for a few seconds, the PT will do an auto zero (same as the calibrate at the beginning).  When you ride outside, this usually happens on a regular basis.  On the trainer, not so much.

Side question.  Do folks with Quargs calibrate mid rides outside (or even on the trainer) routinely to keep the data solid?  I do it at the beginning but rarely during a ride...

With temperature changes over the course of a ride, I wonder if there's much drift or so minimal it's not an issue intra-ride.  Sorry if this was clear to others in the above...  Wondering about degree of change over such a short time frame rather than over the life of the equipment.

Thanks

Matt

I do, particularly on long rides outside I can see some significant drift. If I understand it correctly though in the newest firmware update they changed it so that it does it automatically when you coast, but I still do it out of habit. So before when the Quarq got a cadence reading (from pedaling backwards) and a zero power reading it reset the offset (calibrating is actually a different thing, but Garmin has conflated that). This similar to power tap, when it gets a zero power meter and an RPM from the wheel, it rests the offset. With the Quarq it now resets the offset when it gets a zero power reading and no cadence. I like it better the other way and I think it still works as well. On my Garmin vectors you also pedal backwards to reset the offset - the good thing about the vectors is that if you are using a Garmin head unit it gives you a notice that it is reset. BUT you have to be careful when you pedal backwards when in your largest gear; the clearance between the chain and the plug that goes in to the spindle is very close and you can shear it off with the chain. Don't ask me how I know this....



Look at the number returned at the initial calibration and do a calibration at the end. Take the difference between those numbers and divide by 3. That is is the amount of drift in watts

Pre firmware 21, the initial number would read high due to a bug so if you relied on that number, never did a manual zero, you were probably reading about 6 watts high right off the bat and 10 to 15 watts by the end

I find that with FW21 or greater, if you zero after 10min, there is very little drift after. All of it seems to occur in the first 10minutes.

Edited by marcag 2015-01-22 12:00 PM
2015-01-22 11:47 AM
in reply to: 0

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Subject: RE: SBR "U"

Originally posted by marcag
Originally posted by axteraa

Originally posted by marcag Why do I feel I instigated this check :-). I think you should redo the test with the doors closed :-) You never zeroed the P2max, only the PT, correct ?

I was using some of your french swear words this morning.  

Both were zeroed at the same time.  It's just a coast to trigger both of them (not a back pedal like a Quarq)

hmmmmmm. If I were to bet I would say it's an auto-zero issue and not a temperature drift. Yes, opening the windows cools things a bit but you didn't drop the temperature of the room dramatically. I know for a fact that I had auto-zero problems with my powertap in the past. It probably doesn't appear on an outdoor ride because it auto zeros frequently so you may have an interval of time with bad data but it comes back. I noticed it when riding the PT on the computrainer. They would be almost aligned, I would coast and they wouldn't be aligned. I would coast and they would come back aligned. I would try doing a my VO2 workouts with the 2 side by side, with no autozeroing to see if they drift or not. stupid power meters.....

I will probably run the two together for a bit just to see what happens.

 Edit: not because I will do anything about it, more out of curiosity.



Edited by axteraa 2015-01-22 11:48 AM
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