It is the cheapest way to train with power, comparing to SRM and powertap. I already own a hr monitor that will work with the optional power option. I'm sure it will have some accuracy issues comparing to a srm, but let me know what you guys think about it.
Any opinions on Polar Power option?
Tue, 01/31/2006 - 3:46pm
Tue, 01/31/2006 - 5:25pm
#1
Some Data
In my experience, a properly installed and set-up Polar power meter is quite accurate. Others have the same observation. While I never took the time to run both my Polar and PowerTap simultaneously, I do save files and can compare identical rides, approximately one year apart. The analysis includes: 1) An out-and-back totally flat ride; 2) A long climb; 3) A short climb; 4) A long ride. Below is the comparison:
Out and Back Flat:
Polar 5/13/2004 - 19.5 miles; 21.5 mph; 281 watts
PT 5/12/2005 - 18.7 miles; 21.7 mph; 280 watts
Long Climb
Polar 6/6/2004 - 4.5 miles; 11.8 mph; 311 watts (predicted 317 watts)
PT 6/4/2005 - 4.5 miles; 11.4 mph; 305 watts (predicted 312 watts)
Short Climb
Polar 3/24/2004 - 0.65 miles; 10.6 mph; 357 watts (predicted 351 watts)
PT 4/19/2005 - 0.64 miles; 9.9 mph; 330 watts (predicted 334 watts)
Another Long Climb, mostly constant gear (39X27)
Polar - 3.93 miles 8.1 MPH; 329 watts; 29:05 time
PT - 3.96 miles; 7.2 MPH; 265 watts; 33:04 time
(Its me that was off, not the power meter!)
Long Ride
Polar 03/7/2004 - 67.6 miles; 17.6 mph 189 watts
PT 3/13/2005 - 67.8 miles; 18.0 mph 190 watts (faster speed due to less wind at beginning when oblique, then more wind at end when its a tailwind see below)
3/7/2004 Conditions:
09:45 AM 39.2 °F; 53%; West 17.3 mph; Mostly Cloudy
10:45 AM 41.0 °F; 53%; West 11.5 mph; Mostly Cloudy
11:45 AM 42.8 °F; 53%; West 11.5 mph; Scattered Clouds
12:45 PM 42.8 °F; 49%; West 11.5 mph; Clear
01:45 PM 44.6 °F; 49%; West 9.2 mph; Clear
02:45 PM 46.4 °F; 43%; West 6.9 mph; Scattered Clouds
3/13/2005 Conditions:
09:45 AM 35.6 °F; 56%; 29.76 in; West 9.2 mph; Scattered Clouds
10:45 AM 35.6 °F; 56%; 29.77 in; West 8.1 mph; Mostly Cloudy
11:45 AM 37.4 °F; 48%; 29.76 in; WNW 10.4 mph; Scattered Clouds
12:45 PM 37.4 °F; 41%; 29.76 in; WNW 11.5 mph; Scattered Clouds
01:45 PM 37.4 °F; 41%; 29.75 in; West 13.8 mph; Scattered Clouds
02:45 PM 37.4 °F; 41%; 29.76 in; West 12.7 mph; Scattered Clouds
The results speak for themselves when a Polar is properly installed and calibrated.
Tue, 01/31/2006 - 5:53pm
#2
I bought a Polar power option kit for the reason of price (already have a Polar HRM). I spent several hours fitting it and it worked for all of 5 minutes. I unwound all the wires and took it back to the LBS and got a new one. Spent an hour setting up the new one (quicker second time) and it worked for all of 5 minutes until I realized the battery case was loose and that's why it was all screwed up. Spent 30 minutes trying to improvise a solution because I really really wanted it to work. In the end I took it back and asked for my money back.
Aside from the direct experience above, my general observation is that these things are really fragile in the way they're built and that doesn't fit with wanting to cycle thousands of miles and have it work.
I started with the idea that I wanted to train with power and SRM is just crazy expensive, and Powertap is tied to a specific back wheel (and more expensive). My solution for now is just not to train with power. I'm considering Powertap but that will be tied to a wheel purchase (any advice on the best Powertap wheel options???).
Tue, 01/31/2006 - 6:06pm
#3
Experiences Vary
I did have problems with the first one I owed, one of the earlier models. Polar replaced it but I have not had any problems, save for a broken wire. I actually run one on a mountain bike and have not had problems.
The wire issue is, however, a true reliability concern. Keep in mind Power Taps are not without their problems -- temperature and moisture sensitive. As for SRMs, I have no personal experience to relate.
Tue, 01/31/2006 - 6:46pm
#4
It depends on ..
They can really put any wheel on a PT hub. It depends on what your goals are. If your just looking to train than a Mavic wheel will do. If your looking for more performance , Bontrager makes high performance wheels with various spoke configurations as well as Zipp. I have both Mavic and Zipp 404s w/PT hubs. I favour the 404's since they have a better ride, climb better and save myself considerable wattage over the Mavics. I'm not a time trialist or anything like that but at 210 lbs
I'm not the most aerodynamic thing on two wheels so every little bit helps....
SB
Wed, 02/01/2006 - 3:35am
#5
Not Really Any Wheel
The PowerTap hub can be built into most wheels, not any wheel (actually rim). For example, it cannot be built into a Mavic Kysrium, nor a Reynolds Stratus DV, both of which I own. So, if you are not particularly wheel sensitive, you can get a pretty good pre-built wheel.
Wed, 02/01/2006 - 7:03am
#6
really..?
"I must have been mis-informed . Some idiots @ A3Sports.com said "" his wheel builders are the best in the world and can mount a PT hub to any rim"" ...
Whatever that meant...
S"
Wed, 02/01/2006 - 7:31am
#7
PowerTap Hubs...
I believe that PowerTap hubs come with 32 holes for spokes. While you could use fewer spokes, I doubt the hub is strong enough to withstand the extra tension that using fewer spokes would require.
Bob
P.S. Oops, I'm wrong. The hubs are available in 24, 28, and 32 holes.
Wed, 02/01/2006 - 2:29pm
#8
20 Hole Rims
"24,28,32 is true. Reynolds (and a couple other rims) are 20 hole. Thus, a Powertap can be built into any 24, 28 0r 32 hole rim as follows:
""The flanges are drilled for 14 or 15 gauge spokes. Use at least a two-cross pattern on both sides of the hub. Due to the design of the hub, the load path is not the same as with a conventional hub. Slotting the hub flanges to accommodate bladed spokes is not recommended and will void the warranty."""
Tue, 01/31/2006 - 5:28pm
#9
From Somebody Else
"More Polar calibration:
""I'm doing 20 indoor CompuTrainer group sessions. We've just finished
the 3rd week and I'm finding the numbers shockingly close. Each session
is about 50 minutes long.
Polar 226W. CT 230W.
The worst I had was Polar 208W, CT 220W. Thus, it seems the worst it's
been on AVERAGE watts is 5%. It's averaging about 2% off from the
CompuTrainer.""
Regarding the outlier, it is agreed the cause is probably slippage from the unit not being clamped consistently, a well known trainer problem that results in power under-reporting.
This probably the best comparison:
http://www.biketechreview.com/archive/pm_review.htm
"
