aaronmcd

Slowtwitch! Forgot about that. But nothing anywhere near $600. Wheelsets start around $800 on Ebay, so I'm wondering if wired is so bad it's worth parting with an extra $450 + computer.
Or an extra $125 + computer + front wheel for this: https://www.ebay.com/itm/Powertap-Eli...item4177ce2573

bikepro

They work just fine. You will have a single wire that runs from a "shark fin" mounted on the left chain stay. The wire can be routed up the down tube to the computer.

spdntrxi

I've seen g3 hubs on ebay in the 500s.. I got mine sometime ago for 525.

jsutkeepspining

I dont like any type of "guessing" or any source of inaccuracy in my power measurements, so the stages in my mind is out, especially considering how my left leg is the stronger leg, and the leg. So say i went out and did some sprints, and just lead with my left leg only, and got huge numbers, those wouldn't be comparable to a day when i did sprints that started with my right leg.

Go with a cheap ptap wheel. You wont regret it (plus who cares about fancy wheels when you can have power . I used to ride around with one front aero wheel and a ptap rear wheel. It never slowed me down).

waterrockets 

In that case, all power meters are out. None of them are measuring power. They're all making assumptions on error, then calculating power off of a few measurements, which all bring their own error into the mix. SRM, PT, and Quarq are great, but you're not escaping "any type of 'guessing' or any source of inaccuracy."

echappist

Yes. They all have errors and make assumptions. In which case, we should save ourselves some $$$ and just use iBike.

shovelhd

Rpe.

globecanvas

Joke:

An fireman, engineer, and mathematician are in adjoining hotel rooms. Through a remarkable coincidence, a small fire breaks out in each of their wastebaskets.

The fireman goes into the hall, gets the fire hose, pulls it back in to the room and douses the fire.

The engineer notices a cup of water by the sink, does a quick calculation, pours the water on the fire and puts it out.

The mathematician notices a cup of water by the sink, does a quick calculation, says "trivial!" and goes back to sleep.


... Anyway, I think it's important to understand your engineering needs before ruling out a power meter based on accuracy. The majority of power meter users are targeting numbers for training, and pacing efforts. For those users, there is no practical difference between 1% and 2% accuracy. (An SRM showing 300w could be measuring actual power anywhere between 297 and 303 watts; a Stages showing 300w could be measuring actual power anywhere between 294 and 306 watts.)

A minority of power meter users are doing specific left vs right leg drills, targeting peak sprint power numbers, or doing genuinely scientific post-ride analysis where the difference between 1% and 2% accuracy is meaningful.

No power meter is perfectly accurate, some power meters are more accurate than others. I think the difference between a more accurate and less accurate power meter is smaller than most people understand, and there are relatively few practical applications where more accurate is meaningfully different from less accurate.

rbart4506

Who cares about sprint power? Shouldn't only matter on race day and winning will tell you if your sprint is working...

shermo

I can tell the difference between doing a 20 minute interval at 294 or 306W. 5W difference no, 10W difference yes. Reasonable precision is important for training, not so much accuracy though.

Actually, is an accurate power meter useful for anything other than e-wang?

waterrockets 

Why are all you younguns so polarized? "I won't use anything with error!"

"Oh, wr pointed out that they all have error -- Let's not use anything then."

freaking waste of ASCII

Ygduf

example where the # matters and not the consistency of the meter?

tetonrider

the accuracy vs precision argument gets trotted out all the time. precision is what is important, right? seems to make sense.

here's where it breaks down: in many cases, people will not own only one power meter during their lifetime. there are warranty replacements, upgrades, brand changes, a new meter for a 2nd device, etc.

if one does not have accuracy and precision, there are data problems that will emerge at some point. when one trains with inaccurate numbers (especially if they were high), it is very hard to accept that they were invalid.

there are pros and cons for every PM out there. everyone chooses what is most important to them, but i believe that many people do not realize the importance of accuracy until later in the game. i made this mistake and have a few years of bad data.

having the ability as an end-user to check slope proves to be an important feature over time.

furiousferret

Been cycling 8 years and still don't own a PM, this winter I'm going to pick one up. We just bought a house in June and should have all our debt from the purchase/repairs off the books in a month or two. I'm fighting the urge to just get one now but my policy is to have a clean credit balance before I buy 'toys'.

I wouldn't say that I have plateaued but am at the point were not being able to measure my ability is setting me back, but being in an area where many of my ride times are determined by the wind its hard to gauge if the wind assisted PR is an improvement or...wind assisted. Similarly its hard to tell what wattage I'm putting up while hammering into 40 mph headwinds at 12 mph. Back in the day the improvements used to be noticeable, now not so much.


Still undecided between a Powertap and Garmin Vector. Since I ride my TT bike and Road Bike about the same, I want to swap things out. My TT bike is SRAM and the Roadie is Campy which eliminates any crank, but on the G3 I can swap out the cassette, which isn't too hard. Leaning towards the Vector but I really want to wait and make sure there aren't any glaring issues.

Ygduf

Get the vector. Pedal Based is ideal and we need early adopters to help work out the kinks.

echappist

how many Hail Maries would you need to say if you were to run a Quarq Riken on a Campy bike? Oh the horrors!

JohnKScott

My PowerTap stopped sending power data to my Garmin Edge 500 on the last 10 minutes of my ride on Friday night. Figured it's time to replace the hub batteries. Rode my bike to Walgreen and then the bike shop on Saturday morning (power now working - figured the batteries were giving their last breath of life like they do sometimes). Had bike shop put in new batteries and ordered a hub removal tool so I can do this in the future. Left bike shop and I can't get the PowerTap to sync with my Garmin. Finished ride with out power. Googled. Think I'm doing everything right.

Figured I'd wait until I get the hub removal tool and then pop it off and make sure the batteries were put in the right way and seated properly. Any other thoughts? Anything I'm missing? Anyone else had this issue?

Creatre

I did that once and I put that batteries in upside down. Also make sure the batteries were good. Definitely just sounds like a battery issue to me.

shovelhd

Make sure they are the silver oxide variety. The cheap ones will not last very long.

JohnKScott

Gracias gentlemen.

I'll just be patient until I get the hub tool. It's about the ride and not the numbers anyway right?

waterrockets 

So many ways to open that thing w/out the tool.
Jar opener/rubber pad.
Make a tool by nailing/gluing/screwing two boards the right distance apart (don't use boards with an eased edge).
Set a bench vise to the correct width, set wheel on it with cap in position, then turn wheel.
Channel-Lock pliers set so they'll be parallel at the correct width.

None of these will mar the cap.

Creatre

I tend to agree, I did various methods when I had my powertap. However, the tool is a lot easier. I usually spun over to the LBS which would let me use their tool for free. Much less of a pain.

waterrockets 

Well, I like executing DIY stuff, and abhor going out of my way to an LBS unless it's for something I can't DIY. I can work on my bike at home while helping kids w/homework etc.

shovelhd

I use the jar lid thingy.

furiousferret

Is that an option? You can buy a Quarq and swap them out between a SRAM and Campy (both 10sp)?