Power Meters and Pedaling Effectiveness

[RapDaddyo]

Yes to both. The SLs seem to have started out o.k. and then it seems some parts came in out of spec and many had to be recalled. I can't afford an SL right now so haven't been following very closely on what the current **** is. Call 'em up and find out.

Thanks for the input. I will call them and will let you know what I find out. I manufacture parts out of 7075 aluminum alloy, which is probably what they are using in the new model -- that's probably how they got the weight decrease. I'll find out what I can about their mfg./quality control processes. I'll let you know what I find out.

 

[ric_stern/RST]

The SRM amateur is only slightly better than the polar in terms of accuracy and precision - that unit only uses two strain gauges and often times has non-linearities in its torque response. (I should say that it may be inaccurate - some are good and some are bad. Some amature users have reported contacting SRM and getting a "well, what did you expect?" as their response)

This is what i have found, and is why i'd recommend the SRM Pro

The pro on the other hand has eight gauges, just like the powertap and seems to work pretty well. Most pro users who know what they're doing calibrate them often though as sometimes they drift too. (powertaps are not calibratable by the user so....we just pray that they stay accurate!).

To clarify the SRM Amateur has two strain gauges, while the SRM Pro has four. The SRM Science has eight (originally it used to have twenty if memory serves me correctly). Thus, the PT has double the strain gauges of the Pro.

I've found that the PT stays calibrated for quite a while (2 - 3 years) and then needs calibrating.

When people ask me I usually recommend the powertap as it seems to be a no-muss no-fuss solution at a reasonable price. I'd stay away from the new PT-SLs for a while though until they get the manufacturing bugs worked out of them. If you've got money to burn, go ahead with the SRM pro.

There has been a temporary halt in production with the SLs, although in the twelve i sold prior to the halt only one has had the faulty torque tube issue (zero offset keeps drifting so data is useless).

Ric

 

[beerco]

To clarify the SRM Amateur has two strain gauges, while the SRM Pro has four. The SRM Science has eight (originally it used to have twenty if memory serves me correctly). Thus, the PT has double the strain gauges of the Pro.

I stand corrected.

Interestingly in the stuff I've found about strain gauges, eight is the number most manufacturers call a "full rosette" which means you have two sets of four gauges which usually get glued to two planes perpendicular to each other. I've always felt that that was the minimum required to get good strain data and am surprised to hear that the pro only has four gauges. 20 on the old science is rediculous....leave it to them Germans

 

[ric_stern/RST]

I stand corrected.

Interestingly in the stuff I've found about strain gauges, eight is the number most manufacturers call a "full rosette" which means you have two sets of four gauges which usually get glued to two planes perpendicular to each other. I've always felt that that was the minimum required to get good strain data and am surprised to hear that the pro only has four gauges. 20 on the old science is rediculous....leave it to them Germans

i believe what you describe (2 sets of four) is how the PT is configurated...

and they have since dropped the Science to 8 as it was 'overkill'?

ric

 

[RapDaddyo]

Yes to both. The SLs seem to have started out o.k. and then it seems some parts came in out of spec and many had to be recalled. I can't afford an SL right now so haven't been following very closely on what the current **** is. Call 'em up and find out.

I called CycleOps and got an update on the SL. It's not a pretty picture. They have both manufacturing and electronics problems with the units. They outsource the electronics, so they don't have complete control over correcting the problems. The only thing they are prepared to commit to is that they hope to begin shipping the units again "by the end of the year." In the same breath, the person I talked with said that they wanted to keep it "open ended." This tells me that they are in the early stages of re-design and re-prototyping and re-testing, and I don't place much confidence in the end of year estimate. Until you have a design solution for the problems and at least a working prototype of the new design, you aren't in a position to estimate the availability of new production units.

This poses a difficult decision. It's either the PT Pro or the SRM Pro. The PT SL is months away from availability and the SRM Amateur is a waste of money. The PT Pro will drop in value like a stone after the SL comes out, so it's really a one-year investment. Decisions, decisions.

 

[ric_stern/RST]

I called CycleOps and got an update on the SL. It's not a pretty picture. They have both manufacturing and electronics problems with the units. They outsource the electronics, so they don't have complete control over correcting the problems. The only thing they are prepared to commit to is that they hope to begin shipping the units again "by the end of the year."

That is significantly different to what i was told this afternoon...

 

[RapDaddyo]

That is significantly different to what i was told this afternoon...

I don't know what to tell you. I asked my questions carefully and took notes. But, since I don't know the people at CycleOps personally, I can't be sure that the person I talked with has the latest information. It's a small company, so there's no reason he shouldn't. I mean, this isn't Boeing we're dealing with -- the whole company can probably meet in the lunch room. But, he was absolute in being non-committal about an estimated date for shipping the corrected units. What he really wanted to say was that it is "open ended." I think the "by the end of the year" estimate was just a guess as opposed to a firm date based on a known sequence of events and project plan.

 

[ric_stern/RST]

I don't know what to tell you. I asked my questions carefully and took notes. But, since I don't know the people at CycleOps personally, I can't be sure that the person I talked with has the latest information. It's a small company, so there's no reason he shouldn't. I mean, this isn't Boeing we're dealing with -- the whole company can probably meet in the lunch room. But, he was absolute in being non-committal about an estimated date for shipping the corrected units. What he really wanted to say was that it is "open ended." I think the "by the end of the year" estimate was just a guess as opposed to a firm date based on a known sequence of events and project plan.

i may know more later/tomorrow

 

[RapDaddyo]

i may know more later/tomorrow

For what it's worth, I talked with a Powertap/SRM dealer (also a rider and coach) in Los Angeles about the SL. He sold 8 before they halted production, 7 of which had to be returned. His latest info. on the availability of the new SL is "anywhere from a few months to end of the year."

 

[beerco]

This poses a difficult decision. It's either the PT Pro or the SRM Pro. The PT SL is months away from availability and the SRM Amateur is a waste of money. The PT Pro will drop in value like a stone after the SL comes out, so it's really a one-year investment. Decisions, decisions.

Personally, I'm no fan of the SRM. If I was you, I'd buy a used PT pro until the SL comes out then buy the hub only - this way you'll have two wheels - train & race and you'll still have spent less money than on a new SRM pro - and no calibration issues either.

 

[RapDaddyo]

Personally, I'm no fan of the SRM. If I was you, I'd buy a used PT pro until the SL comes out then buy the hub only - this way you'll have two wheels - train & race and you'll still have spent less money than on a new SRM pro - and no calibration issues either.

So, the PT Pro and SL computers are interchangeable?

 

[beerco]

So, the PT Pro and SL computers are interchangeable?

AFAIK, they are one and the same.

 

[ric_stern/RST]

AFAIK, they are one and the same.

The computers are the same, you can just swap the hub/wheels over.

 

[gholl]

As a former racer (many years ago) and as a physician, I recently became interested in the use of Power Meters (PM) in training.
As the posters on this and other threads have noted, it's a complicated and new field. As in all areas of novelty there is a great lack of knowledge and many self appointed experts-many with a financial axe to grind. Beware.
My experience to this point is that PM's are useful in that they give an objective target against which to train. Heart rate (HR) is a reactive phenomenon influenced by many other factors. The difficulty, a very great difficulty, is in determining accurate Endurance, Tempo, etc. zones. This is because lab and road conditions don't match and results given by different PM's don't match either. The technical problems with PM's are too numerous to itemize here. PM's all have unique technical problems that one will have to tolerate if you go the PM route.Like all cycling equipment, aftermarket service for PM's is very, very important-each cyclist will have to make a judgement about this. Often the shopping process will tell you who will be there after the sale and who is out for the buck. There is presently no perfect PM.
Good software will help in interpreting PM results.
The physical challenge using PM's is not only to maintain one's training zones but to learn the proper pedaling technique to insure a smooth power output-also not easy.
One can, and must, in my opinion, also continue to monitor HR, cadence, etc. as before the advent of PM's, but learn to use them as adjuncts to cycling fitness and not as a training goal per se.

 

[RapDaddyo]

As a former racer (many years ago) and as a physician, I recently became interested in the use of Power Meters (PM) in training.
As the posters on this and other threads have noted, it's a complicated and new field. As in all areas of novelty there is a great lack of knowledge and many self appointed experts-many with a financial axe to grind. Beware.
My experience to this point is that PM's are useful in that they give an objective target against which to train. Heart rate (HR) is a reactive phenomenon influenced by many other factors. The difficulty, a very great difficulty, is in determining accurate Endurance, Tempo, etc. zones. This is because lab and road conditions don't match and results given by different PM's don't match either. The technical problems with PM's are too numerous to itemize here. PM's all have unique technical problems that one will have to tolerate if you go the PM route.Like all cycling equipment, aftermarket service for PM's is very, very important-each cyclist will have to make a judgement about this. Often the shopping process will tell you who will be there after the sale and who is out for the buck. There is presently no perfect PM.
Good software will help in interpreting PM results.
The physical challenge using PM's is not only to maintain one's training zones but to learn the proper pedaling technique to insure a smooth power output-also not easy.
One can, and must, in my opinion, also continue to monitor HR, cadence, etc. as before the advent of PM's, but learn to use them as adjuncts to cycling fitness and not as a training goal per se.

Reading your posting, I can't tell where you're coming from in terms of your personal experience with PMs. Do you use a PM? Which one? How long? What has been your personal experience in terms of how you train differently (better?) with PM vs. w/out PM? Have you established your personal MP/Endurance curve? What benchmarks did you use for MP -- 1 min, 5 min, 20 min? It would help to know if your remarks are based on personal experience with PMs or reading about PMs.

 

[gholl]

Reading your posting, I can't tell where you're coming from in terms of your personal experience with PMs. Do you use a PM? Which one? How long? What has been your personal experience in terms of how you train differently (better?) with PM vs. w/out PM? Have you established your personal MP/Endurance curve? What benchmarks did you use for MP -- 1 min, 5 min, 20 min? It would help to know if your remarks are based on personal experience with PMs or reading about PMs.

Your questions are well put. I've been using a Computrainer for many years(9)and an SRM Amateur for several months now under the guidance of a professional coach. As you can intuit from my postings, I have established a set of training zones using both-they are still in flux. I'm not yet happy with the zones.
My professional training and lab experience (Clinical Pathology) as well as my years (45+) in cycling aid me in evaluating the use of PM's in training.
Let me tell you yet again, this is a very young science-there is very little known, the instrumentation is primitive and the level of expertise very limited. Be very cautious about what you hear and read.
As to whether there is benefit in using a PM, I would say definitely yes-since the goals which, if properly established, are more objective than HR, etc. However, these other parameters cannot be summarily eliminated from a cyclist's consideration-they have much value. Everything must be taken into account-and by someone properly trained to do so-not easy to find.
Propriety prevents me from saying more. If you desire to email me privately at my lab, perhaps that can be arranged. I don't desire to damage a product or coach's reputation.

 

[RapDaddyo]

Your questions are well put. I've been using a Computrainer for many years(9)and an SRM Amateur for several months now under the guidance of a professional coach. As you can intuit from my postings, I have established a set of training zones using both-they are still in flux. I'm not yet happy with the zones.
My professional training and lab experience (Clinical Pathology) as well as my years (45+) in cycling aid me in evaluating the use of PM's in training.
Let me tell you yet again, this is a very young science-there is very little known, the instrumentation is primitive and the level of expertise very limited. Be very cautious about what you hear and read.
As to whether there is benefit in using a PM, I would say definitely yes-since the goals which, if properly established, are more objective than HR, etc. However, these other parameters cannot be summarily eliminated from a cyclist's consideration-they have much value. Everything must be taken into account-and by someone properly trained to do so-not easy to find.
Propriety prevents me from saying more. If you desire to email me privately at my lab, perhaps that can be arranged. I don't desire to damage a product or coach's reputation.

Thanks for the additional info about your personal experience w/PMs. I tend to get pretty well informed before I make important decisions and I consider spending $1K+ an important decision. Since I did my serious cycling before the availability of HR, cadence or PMs, and was reasonably successful, I don't hold out any bike computer info as the "holy grail." But, since the objective of cycling is to apply as much force to the cranks as possible for the required duration, it is pretty obvious that it would be useful to know how much power one is applying to the cranks at any point in time and averages over time. I understand the technologies underlying all four of the available products (I have read the patent applications), and I think I have a pretty good feel for the technical and maintenance shortcomings of each. I see a lot of discussion about accuracy, but to the extent that we're talking about 1.5% or 3%, I can't figure out why I care, so long as my device is consistent. If 200 watts is always 200 watts, it's fine with me, even if it's really 205 watts. Intermittent readings are, however, a problem.

As to training with a PM, I don't know that it will change my approach to training very much except that I will probably define my rides in power terms with a spot check of HR. I have a pretty simple philosophy for training. I ride for about 3 months mainly spinning whatever gear I can turn without feeling like I'm pushing hard. Then I start doing hard days followed by easy days. Hard is hard enough to make my thighs and lungs burn for at least 5 minutes at a time, sometimes more. Easy is easy enough to have a conversation with a riding buddy. The main difference is that with a PM I'll know what hard and easy are in watts. Whether that'll cause me to change the way I train, I don't know yet. But, there's no way I'm going to have a training schedule that looks like a NASA launch schedule.

 

[gholl]

Thanks for the additional info about your personal experience w/PMs. I tend to get pretty well informed before I make important decisions and I consider spending $1K+ an important decision. Since I did my serious cycling before the availability of HR, cadence or PMs, and was reasonably successful, I don't hold out any bike computer info as the "holy grail." But, since the objective of cycling is to apply as much force to the cranks as possible for the required duration, it is pretty obvious that it would be useful to know how much power one is applying to the cranks at any point in time and averages over time. I understand the technologies underlying all four of the available products (I have read the patent applications), and I think I have a pretty good feel for the technical and maintenance shortcomings of each. I see a lot of discussion about accuracy, but to the extent that we're talking about 1.5% or 3%, I can't figure out why I care, so long as my device is consistent. If 200 watts is always 200 watts, it's fine with me, even if it's really 205 watts. Intermittent readings are, however, a problem.

As to training with a PM, I don't know that it will change my approach to training very much except that I will probably define my rides in power terms with a spot check of HR. I have a pretty simple philosophy for training. I ride for about 3 months mainly spinning whatever gear I can turn without feeling like I'm pushing hard. Then I start doing hard days followed by easy days. Hard is hard enough to make my thighs and lungs burn for at least 5 minutes at a time, sometimes more. Easy is easy enough to have a conversation with a riding buddy. The main difference is that with a PM I'll know what hard and easy are in watts. Whether that'll cause me to change the way I train, I don't know yet. But, there's no way I'm going to have a training schedule that looks like a NASA launch schedule.

I think you've got the right take on matters. Accuracy is pretty much the same for all the entry level PM's and is not a major issue. However, the ability to produce smooth usable Wattage data is VERY important-as you'll soon see. So pay good attention while you're shopping. Don't forget about aftermarket support-you're going to need it whatever your choice.
Also pay very careful attention to your choice of software-you must be able to make sense of the data you've generated.
Your overall training program is another critical choice-this needs to be carefully adjusted to your personal goals- my suggestion would be to use a coach (a coach expereinced in the use of PM's) unless you're really already a very well trained and experienced rider. Good luck!

 

[RapDaddyo]

I think you've got the right take on matters. Accuracy is pretty much the same for all the entry level PM's and is not a major issue. However, the ability to produce smooth usable Wattage data is VERY important-as you'll soon see. So pay good attention while you're shopping. Don't forget about aftermarket support-you're going to need it whatever your choice.
Also pay very careful attention to your choice of software-you must be able to make sense of the data you've generated.
Your overall training program is another critical choice-this needs to be carefully adjusted to your personal goals- my suggestion would be to use a coach (a coach expereinced in the use of PM's) unless you're really already a very well trained and experienced rider. Good luck!

Thanks for the input. When you say, "smooth usable wattage data ...", do you mean during the ride or post ride, or both? What's your take on the ability to produce smooth usable wattage data with the SRM Amateur? And, what is your experience with after-sale support for the SRM? What is warranted and how long is the warranty? I'm not overly concerned with the software choices, so long as the raw data can be exported in a standard file format (ASCII, CSV, etc.). If the vendor-supplied software and after-market software packages don't meet my needs, I'll just write my own analysis program. It's just a time-series data file and there are only a few variables of interest. It seems to me that the only parts of a ride that matter are the parts where I'm going hard (i.e., trying to max out my power output over a specific time duration). When I'm pedaling easy, I don't think I need a computer analysis to tell me how easy I'm pedaling.

As to your suggestion to get a coach experienced in the use of PMs, I may do that if I decide to race again. Right now, I'm just trying to earn the right to call myself a cyclist again. I've lost 22 pounds in two months just from riding regularly and I feel like I'll lose another 15 pounds before I settle into a riding weight. I think my body changes will continue for a couple more months, not a carefully managed change but just the result of 14 hours a week on the bike and eating a healthy diet. My decision to race again won't come for at least several months and my first race will be maybe a year from now. By then, anybody who calls himself a cycling coach will be experienced with training cyclists riding with PMs. I believe PMs will rapidly become (if not already) just a standard component of serious cyclists' bikes, in the same way HR and cadence computers have become standard components. I'm actually more interested in reading the scientific journals about exercise physiology and training effects, how and why the body develops strength and endurance. Any suggestions for my reading list?

One more thing. You didn't respond to my previous question about creating your personal MP/Endurance curve. Have you done this and what benchmarks did you use?

 

[jws]

Any suggestions for my reading list?


Here's a start:

a good power forum:

http://lists.topica.com/lists/wattage/read


the first 6 items here (especially the guides by Coggan and Howe):

http://www.midweekclub.com/articles/


the only software to use and some great info (look at "Power411"):

http://www.cyclingpeakssoftware.com/


Ric's site with good power info:

http://www.cyclecoach.com/