Yellow head units are slower. Go with SRM Red or Black.

Otherwise, if you use the Search..you'll note this topic comes up a few times a day...lots of good info.

SRM!

PowerTap. Accuracy is the same, and for about the cost of an SRM you can build both a training and a race wheel up--and use it on 2 or more bikes. I've used PT for 2 years and have found no problems with it. All my athletes who are on power are one PTs. The Power Agent software is great as well.
Now you can get a 2009 ANT+ version and let it display and interact wtith your Garmin 705 for all the GPS data as well as the PT data.

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Brian Grasky
Grasky Endurance: World Championship Triathlon Coaching; Professional Training Camps
RETUL fitter, Biomechanist, USAT Level 3 Coach, USAC Level 2 Coach

I'd argue that PT is potentially more accurate because you don't have to worry about zero torque drift (or at least none of my 3 PTs ever did, but my SRM drifted a lot when new, although it become only a very minor thing later on).

That said, I like the SRM much better overall. No wheel worries, cleaner mounting (though wireless PT fixes that), better waterproofing (if you care) and more reliable in my experience, better on-board data, works with a disc wheel. The PT pros are that it's simpler, cheaper (you can argue that if you need >1, then maybe not, depending on wheel choice), great customer service (I had 2 sent back, or was it 3?), battery lasts really long.

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Too f@ckin depressed from various injuries to care about having a signature line.

Sponsored by Blue Shield PPO.

Why not a Quarq Cinqo? Few hundred more than a PT and you keep your race wheels...

A little too new and untested for my tastes, but I'm interested in seeing how it works out.

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Too f@ckin depressed from various injuries to care about having a signature line.

Sponsored by Blue Shield PPO.

I am looking into getting the williams wheel powertap. Just wondering what type of wheel is the best with the powertap

I can understand but this is going to be the 2nd gen... Also they are sponsoring a Cervelo team. You can do a quick search, seems like they made good progress.

I have two powertap SL units. One is laced into a training rim and the other into a HED Jet 9 for racing. I prefer the powertap units because I run them on both a road and tri bike and its easy to switch back and forwards. I can use a wheelcover with the rear to make it into a disc.
Waterproofing on the new Powertap hubs is excellent. Both of mine have been ridden in rain, in fact I had mine out for a 3 hour ride in the rain yesterday and it worked flawlessly for the whole time. Their bad rap came from the pro and standard units (no longer in production), I had a couple of these and they would quit working at the sight of water.
I would come down to, if you want to run it on the same bike and easily switch wheels, then SRM (or Quarq), if you want to switch a wheel easily between bikes then Powertap.
The more important thing than which one you get is how you use it to manage your training.........

Kevin

I prefer the powertap units because I run them on both a road and tri bike and its easy to switch back and forwards.

I have an SRM and swaping between bikes is 3-5 minutes tops.

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36 kona qualifiers 2006-'23 - 3 Kona Podiums - 4 OA IM AG wins - 5 IM AG wins - 18 70.3 AG wins
I ka nana no a 'ike -- by observing, one learns | Kulia i ka nu'u -- strive for excellence
Garmin Glycogen Use App | Garmin Fat Use App

True Mark, but swapping my powertap wheel is 1 minute and doesnt require any tools :-) I have BB30 cranks on both bikes which arent so easy to change and also run different length cranksets, with shorter cranks on the tri bike.


Kevin

Powertap. Use it for a while and see if you like being a numbers geek and analyzing endless amounts of data. After you answer that question keep the PT or sell it and buy a SRM if you just have to have one. You'll know in about 2 or 3 months if you like looking at data. Used PT would be the cheapest route into power to see if you really want to deal with the numbers.

uh... uh... uh...

you still gotta use the quick release skewer! that's a tool! :D

True... if you like diff crank lengths that's one thing. Just trying to dispel the myth that SRM's are not easily exchanged between bikes. Wireless makes it a tad easier too.

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36 kona qualifiers 2006-'23 - 3 Kona Podiums - 4 OA IM AG wins - 5 IM AG wins - 18 70.3 AG wins
I ka nana no a 'ike -- by observing, one learns | Kulia i ka nu'u -- strive for excellence
Garmin Glycogen Use App | Garmin Fat Use App

Ahhh, the ever emerging (at least monthly) PT vs SRM battle...

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Brian Grasky
Grasky Endurance: World Championship Triathlon Coaching; Professional Training Camps
RETUL fitter, Biomechanist, USAT Level 3 Coach, USAC Level 2 Coach

I think changing powermeters is the only area where I would be faster ;-) But you could change your SRM at the start of the swim and still beat me out of the water easily at an Oly!
Both good powermeters, you couldnt go wrong either way.

Kevin

if you search you'll find a lot of info out there--this question come up a lot. I'm using both, PT on my TT bike and srm on my road bike. Eventually, when I get around to it I'm going to ditch the SRM.

Cost? I think the cost is about the same, since you eventually will want 2 wheels. Having your PM tied into one wheel can be a problem.

Accuracy? they're both accurate 'enough', though for most people the PT is probably more accurate more of the time.

Durability? I'd say they're the same from what I've experienced or observed.

Switching between bikes? If you use the same size cranks and chainrings, it's easy for either one. I don't, which is a problem for switching the SRM...

For me, the big difference is the computer head functionality, which I find much better (for me) on the PT, and the ability for the device to auto-zero it's torque, which makes for more accurate race files. As others have said though, they'll both work fine--the bigger difference will be how you implement the data into your training.

Contact Timmer or Pauly at Hed Wheels 651-653-0202 about Powertap wheel builds. That is the way to go.

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Ian Stanford
Ally's Bar. AStacher LLC

I have had one of each. While the SRM may run you a bit more they are far more easier to work with. I had problems with both systems. In the end, SRM was much more efficient to deal with as far as customer service and taking care of any problems. SRM seems to hold it's value better as well. SRM software is a bit better than the Powertap software but I ended up using CyclingPeaks software which was the bees knees of them all.
As far as accuracy between the two? I sat in on one of Allen Lim's Powermeter Studies at the University of Colorado. His testing showed nearly identical power numbers under equal testing. So, no noticeable difference.

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Ian Stanford
Ally's Bar. AStacher LLC