Powertap 2.4 SL - expensive innit

vermooten

I so want one, but do I really want to pay a grand?

Import from America? Buy second-hand? (mmm I don't think so) Get something else that's just as good but half the price?

Whaddyareckon?

Cheers,
Andy

BeaconRuth

It won't make you any faster.

Ruth

vermooten

ahhh true enough, there's no substitute / shortcut / cheat for a structured training programme, and I'm in one

my coach strongly recommends training with power over HR, hence my desire to shell out

Bob Tobin

vermooten wrote:

I so want one, but do I really want to pay a grand?

Import from America? Buy second-hand? (mmm I don't think so) Get something else that's just as good but half the price?

Whaddyareckon?

Cheers,
Andy

Give me a call and I'll see what I can do - 01788 556860

Bob Tobin

bob@cyclepowermeters.com

vermooten

Cool I'll call you later!

willbevan

have to admit im tempted by the whole rental...

but which, power tap, ergo, SRM?

Anyone got the pros cons of each?

Bob Tobin

willbevan wrote:

have to admit im tempted by the whole rental...

but which, power tap, ergo, SRM?

Anyone got the pros cons of each?

Powertap
Pros
easy to fit
accurate straight from the box
easy to use
wireless option
Software works on MACs
User replaceable batteries

Cons
Poor software
must use that wheel so if you race with a disc you have no data (or buy the Zipp Powertap disc for 2350 quid)
can only display 3 things at a time on the display
Training wheel + racing wheel starts to become expensive
Wireless uses batteries quicker
Batteries can run out with liittle notice losing data

---

Ergomo
Pros
Customiseable display on head unit shows up to 8 things at the same time including altitude, TSS, IF which the others dont.
Use any wheel
Recharagble battery
Multiple bikes only requires an additional BB


Cons
Requires very careful installation (by a bike shop or ergomo centre)
Only measures 1 leg's output and doubles it
Software windows only
Batteries can corrode if left uncharged for long periods

---

SRM
Pros
Duraace, FSA and Pro Octalink versions quick to move between bikes but need
2 fitting kits
Accurate once calibrated & can be user calibrated unlike the other 2
Very long lasting as no moving parts to wear out.
Good waterproofing
Use any wheel

Cons
Expensive
Very often come inaccurately calibrated from the factory
Calibration drift over time
Software windows only
Changing chainrings can alter calibration
Cables seem to wear out / get damaged quickly

So it depends how many bikes you want to use it on. What your budget is.
What wheels you want to use etc, etc etc.

Hope that helps.

There is no perfect system - they all have potential problems. If you want to talk through what you want to use it for & which would be best for that give me a ring on the number above.

Bob

aracer

BeaconRuth wrote:

It won't make you any faster.

However if used properly it might - which is more than can be said of most of the similarly expensive things people buy.

Skooby

Have a look at

http://www.biketechreview.com/archive/pm_review.htm

liversedge

I've rented a PT from Bob for over a year and vowed to send it back if it wasn't worth it ... he will need to rip if from my dead clinging fingers to get it back.

Don't stress on the software - if you get half interested in this stuff you'll buy Cycling Peaks software - it rocks.

nmcgann

A powertap SL is a good way of saving a little money over the fully wireless version. It is very easy to fit and it's no trouble swapping the wheel between different bikes if you buy extra mounting kits.

As Ruth says, it won't make you any faster just by knowing the power you can produce. It will give you lots of data for later analysis though and that can be very valuable....if a bit depressing on occasion :?

Neil

willbevan

any of them work with the new garmin edge 705?

Also cycling peaks, can it merge say GPS data from a garmin 305, and the power data from a powertap sl?

thanks

Will

liversedge

willbevan wrote:

any of them work with the new garmin edge 705?

Powertap doesn't work with the 705. SRM does.

liversedge

Training Peaks WKO+ 2.2 (they renamed cycling peaks) supports the EDGE here is the blurb from the help file. Merge isn't mentioned in the help files - maybe someone else can confirm or deny.

"Garmin GPS Direct Download and Export to Google Earth!
Now you can easily direct download your Garmin™ EDGE 205/305 or Forerunner 301/205/305 GPS device. Take advantage of CyclingPeaks WKO+ to really dig in to your workout. Unrivaled interval analysis, graphing and power let you visualize your fitness! Import your entire history. Supports reading of Training Center .hst files. Also supports exporting .gpx files, great for Real3D or CRS users. If you download data from a Garmin Forerunner or EDGE, you can seamlessly view your entire workout, or just a highlighted section in Google Earth with a simple righ-click. Create a range, right click and send it to Google Earth. AMAZING!"

vermooten

If I understand the question, then what we want is to run both the Garmin and the Powertap on the same ride. Then download both to the software and press a 'merge' button so that the user can, for instance, look at the power readings and a particular geographical location - e.g. how much power did I use climbing Hardknott Pass yesterday?

I reckon that's not hard to do, not technically - and when I get my Powertap I'll see if it's possible. I doubt it though - you'd have to do some kind of synchronising between the two devices.

willbevan

vermooten wrote:

I reckon that's not hard to do, not technically - and when I get my Powertap I'll see if it's possible. I doubt it though - you'd have to do some kind of synchronising between the two devices.

Can see a plug-in for sporttracks to do this (free program i use instead of garmin training centre as like it so much more)....

Even if not, might be interesting to see how after they merge, if you could export it and go into cycling peaks , hmmm

dennisn

Just out of curiosity, why not get a Polar power sensor. About half the price of a
Power Tap and bundles less than SRM. I don't use one but if I did I'm not sure why
I would even consider paying monster dollars for something that could be bought
for much, much less and gave me the same info. Then again what do I know???
I'm sure someone will chime in with something like "a Polar is only accurate to + or
- 1 percent whereas an SRM gives you accuracy to + or - .1 percent".

Dennis Noward

vermooten

Thanks Dennis, and I did indeed look into the Polar device. It's half the price of the Powertap, which makes it very tempting... but as you rightly say, it's very inaccurate. The article referred to by Skooby above suggests that it's so inaccurate that it's not really worth getting.

All this gizmos are part scientific device and part toy - and I do like my toys.

dennisn

vermooten wrote:

Thanks Dennis, and I did indeed look into the Polar device. It's half the price of the Powertap, which makes it very tempting... but as you rightly say, it's very inaccurate. The article referred to by Skooby above suggests that it's so inaccurate that it's not really worth getting.

All this gizmos are part scientific device and part toy - and I do like my toys.

I didn't mean to say it was inaccurate. I was saying that someone is sure to claim it is.
Think I'll read that article. I might learn something.

Dennis Noward

dennisn

I didn't see anything in that article that said Polar is not worth getting. I didn't see the words
"very inaccurate" as you said I said. Did I say that??? The article didn't contain the word
"perfect" in reference to any one of them. It talked about inaccuracies in all of them.
In any case my dollars are going into building a set of lightweight wheels. Imagine that, me with lightweight wheels. I do like building them.

Dennis Noward

liversedge

dennisn wrote:

I didn't see anything in that article that said Polar is not worth getting. I didn't see the words
"very inaccurate" as you said I said. Did I say that??? The article didn't contain the word
"perfect" in reference to any one of them.

In the opening gambits the reviewer says of the Polar "This method of monitoring chain frequency is not an exact science. Positioning and proximity of the sensor relative to the chain can affect the results" coupled with "The Polar installation was a relatively painful operation" this will yield inaccuracies before you even start on the technology.

Indeed, he goes on to describe issues he expereienced "The erroneous readings that were noticed while riding were obvious. On the initial setup, while riding along on a relatively level grade and shifting through the entire gear range in the big ring, power stayed constant. When I shifted into the 53x21 (I run a 23 in the back, so this was not the most extreme crossover possible) I observed a 40 watt increase in measured power. No matter how the chain frequency sensor placement was adjusted, (raising, lowering, leveling, rotating, translating) the same phenomenon occurred. As a last resort, I swapped out the chain for a longer one and the problem vanished. I can only speculate that the tighter chain originally used was creating an effectively shorter unsupported chain length (due to more friction between chain and gear teeth) and, thus, the higher vibration frequencies (measured power) observed. The problem might also have been resolved by tweaking the chain speed sensor orientation, but that variable was not manipulated at the time."

Of the tech the review says "It should be clear that the PT and SRM have fewer fundamental sources of error than the Polar system". And goes on to describe the calibration available for the SRM and PT.

When reviewing tests "The above plot shows two five second sprints done. The Polar under-reports the first effort by 50% and completely misses the second effort." then later "As the gear ratio increases the difference in the average power between the Polar and the SRM goes from being negative to positive – the Polar measures less power in the 53x23 and more power in the 53x12. The cause of this is unknown, but is interesting nonetheless. It would be expected that an offset in the data would be seen as is seen when comparing the PT and SRM units in the small chainring data presented later. The Polar phenomenon is indicative that there is some sensitivity to gear ratio in the large chainring." then later "The Polar comparison indicates that there is a general decreasing trend over the power spectrum, which means that the Polar consistently under-reports power relative to the SRM as power output increases. Again, this indicates that something odd is occurring with the Polar unit. The SRM and PT slope is much closer to zero as is theoretically expected."

In summarising he says of the Polar "Potential data quality issues (especially on trainer and capturing of max wattage". This is a killer for a device which has one function - to collect data.

I think the review, is quietly damning of the Polar system.

phil s

I got my Powertap 2.4 SL delivered from the States for £560 all in brand new off eBay

dennisn

liversedge wrote:

dennisn wrote:

I didn't see anything in that article that said Polar is not worth getting. I didn't see the words
"very inaccurate" as you said I said. Did I say that??? The article didn't contain the word
"perfect" in reference to any one of them.

In the opening gambits the reviewer says of the Polar "This method of monitoring chain frequency is not an exact science. Positioning and proximity of the sensor relative to the chain can affect the results" coupled with "The Polar installation was a relatively painful operation" this will yield inaccuracies before you even start on the technology.

Indeed, he goes on to describe issues he expereienced "The erroneous readings that were noticed while riding were obvious. On the initial setup, while riding along on a relatively level grade and shifting through the entire gear range in the big ring, power stayed constant. When I shifted into the 53x21 (I run a 23 in the back, so this was not the most extreme crossover possible) I observed a 40 watt increase in measured power. No matter how the chain frequency sensor placement was adjusted, (raising, lowering, leveling, rotating, translating) the same phenomenon occurred. As a last resort, I swapped out the chain for a longer one and the problem vanished. I can only speculate that the tighter chain originally used was creating an effectively shorter unsupported chain length (due to more friction between chain and gear teeth) and, thus, the higher vibration frequencies (measured power) observed. The problem might also have been resolved by tweaking the chain speed sensor orientation, but that variable was not manipulated at the time."

Of the tech the review says "It should be clear that the PT and SRM have fewer fundamental sources of error than the Polar system". And goes on to describe the calibration available for the SRM and PT.

When reviewing tests "The above plot shows two five second sprints done. The Polar under-reports the first effort by 50% and completely misses the second effort." then later "As the gear ratio increases the difference in the average power between the Polar and the SRM goes from being negative to positive – the Polar measures less power in the 53x23 and more power in the 53x12. The cause of this is unknown, but is interesting nonetheless. It would be expected that an offset in the data would be seen as is seen when comparing the PT and SRM units in the small chainring data presented later. The Polar phenomenon is indicative that there is some sensitivity to gear ratio in the large chainring." then later "The Polar comparison indicates that there is a general decreasing trend over the power spectrum, which means that the Polar consistently under-reports power relative to the SRM as power output increases. Again, this indicates that something odd is occurring with the Polar unit. The SRM and PT slope is much closer to zero as is theoretically expected."

In summarising he says of the Polar "Potential data quality issues (especially on trainer and capturing of max wattage". This is a killer for a device which has one function - to collect data.

I think the review, is quietly damning of the Polar system.

So, you're saying that because one person did a bit of testing you believe that his
conclusions are beyond questioning??? Have there been any peer reviews of his work?
It just stands on its own because it was printed in a magazine or you saw it on the web?? Who is this "tester"? Does he have any background in things like this or is he just
some bike magazines resident tester of everything from saddles to QR's?? As you can
probably tell, I'm not a Power Meter user. If you like toys I suppose this is one most people will have to have and with all the "ad-men" telling everyone that they can't live
without one I'm sure millions will be sold. Sorry about all that, I'm starting to rant.

Dennis Noward

liversedge

dennisn wrote:

So, you're saying that because one person did a bit of testing you believe that his
conclusions are beyond questioning??? Have there been any peer reviews of his work?
It just stands on its own because it was printed in a magazine or you saw it on the web?? Who is this "tester"? Does he have any background in things like this or is he just
some bike magazines resident tester of everything from saddles to QR's?? As you can
probably tell, I'm not a Power Meter user. If you like toys I suppose this is one most people will have to have and with all the "ad-men" telling everyone that they can't live
without one I'm sure millions will be sold. Sorry about all that, I'm starting to rant.

I'm saying the review is "quietly damning" of the polar power meter. I was responding to your assertion that "I didn't see anything in that article that said Polar is not worth getting".

As to peer reviews of a web-site review, then no of course his online review isn't peer reviewed. Peer reviews are generally applied to primary sources. There are many other reviews in print and online that question the accuracy, consistency and value of the polar system. I have yet to find a positive review of the polar power meter online or in print. I have yet to meet an owner of a polar power meter that wouldn't rather have a powertap, ergomo or SRM setup.

If you believe power meters are "toys" and a waste of money then great - perhaps you could explain why you believe that to be the case, as opopsed to say a heart rate monitor? But perhaps a new thread would be the best place to do that :-)

aracer

From a scientific basis, the Polar power meter is almost bound to be worse than the SRM or PT, since there are more variables in its method of measurement. It is a very clever idea though! In any case I'd suggest it is probably more accurate than the two newer devices they didn't test there - Ergomo and iBike.

liversedge

aracer wrote:

In any case I'd suggest it [Polar] is probably more accurate than the two newer devices they didn't test there - Ergomo and iBike.

As I understand it the ergomo uses strain guages in the bottom bracket to measure torque but only on one side so any left-right spin-scan or one-legged drills are not possible, but then is that really important? Should be as reliable as srm and pt? The Quarq CinQo (?) uses strain guages in the spider so might be ok and is supposed to be garmin compatible too?

Agree about the ibike tho.

st68

bought my ergomo for chrimbo an i love its already improved my climbing bought the hunter allen book training with a power meter the new software updates from ergomo are great as well

vermooten

I had a nice experience with my rented Powertap the other day. I was on a hot climb being overtaken by everyone in the world, and the voices of doubt pointed out that I'm a useless climber and had no right to be in the company of the others etc etc. I looked at the Powertap computer and saw that I was actually pushing it out nicely, about 335W. That made the voices flee, and I continued at my steady pace, eventually overtaking many of those who'd overtaken me further down th'ill.

dennisn

vermooten wrote:

I had a nice experience with my rented Powertap the other day. I was on a hot climb being overtaken by everyone in the world, and the voices of doubt pointed out that I'm a useless climber and had no right to be in the company of the others etc etc. I looked at the Powertap computer and saw that I was actually pushing it out nicely, about 335W. That made the voices flee, and I continued at my steady pace, eventually overtaking many of those who'd overtaken me further down th'ill.

That's the way to do it. Nice and steady and you'll get them in the end. I know what you're
saying because I too, have been, and continue to be, overtaken by everyone in the world.
Very well put.

Dennis Noward

vermooten

Looks like there's a Garmin-compatible Powertap coming out: http://www.velonews.com/article/77542

grrrrr

unless there's a firmnware upgrade to give the same functionality to existing PTs in which case I withdraw my grrrrr

andrewgturnbull

st68 wrote:

bought my ergomo for chrimbo an i love its already improved my climbing bought the hunter allen book training with a power meter the new software updates from ergomo are great as well

Hi there.

You're doing yourself a disservice! You've improved your climbing through hard work - the power meter has just helped you to apply yourself!

Cheers, Andy