Least expensive way to measure watts ?
 

Not sure if this should be in electronics or here ?

I have a 2000 Gios , that i'd like someway to monitor watts being put out... not sure if i'll be able too, as any thing measuring that i've seen involves changing the crank, but i could be wrong.. hence here asking the questions. :thumb:

http://s1.postimg.org/exgkga727/Gios.jpg

Look for a used PowerTap on Craig's List. They can be had for $400 or so depending on the rim they're laced to.

The crank or pedal based power systems are nice too, but still very expensive.

As far as I know, the cheapest way to get accurate power numbers these days would be to buy a used PowerTap rear wheel. The reading comes from the hub, so you could even just buy the hub and build the wheel yourself if you're handy, they seem to go for $250-300 around here pre-built and used.

For new systems that don't require new cranks, you could look into Garmin Vector pedals, but they're something like $800. Really, there's no uber-cheap way of getting that data on a road bike just yet.

iBike Newton.

The technology is still expensive. i had an bike, a while back. I worked ok. Good enough for me to realize I didn't want/need to know.

Used powertap wheel is probably going to be the cheapest...I've seen the wired ones go for cheap.

The Vector pedals would be a good setup if you want to spend some cash on a power meter.

just saw a video yesterday of a company from Scotland building power meters that thread into the cranks between the pedals, supposed to only cost around $400 but I don't know if they are on the market yet. google it

^ Crowd sourced venture that has about a 1% chance of hitting the market in this decade.

http://limits.technology/about/

It also has a big Q factor problem.

OP, this is the sort of thing you want if you really are looking for bargain-basement prices on power-

Mavic Open Pro 32h Clincher Rear Wheel CycleOps PowerTap Hub Wired PowerTap | eBay

It'll probably sell for ~$250 since it has the head unit and goodies.

Another vote for a used wired PT.

(Great looking Gios, by the way)

+1 Powertap

OP, it's worth mentioning that (as far as I'm aware) a wired PT can export power/heart rate data for a given ride, but you can't merge that data with GPS files if you have a garmin or use Strava on your phone, so you're left with two separate bits of information. If all you care about is getting in to training with power and establishing your numbers, that shouldn't matter too much, but if you want to fully geek out you'd need one of the ANT+ hubs which are a good deal more expensive.

Edited: You can also buy an older hub, use it for a while, and then see if Cycleops/Saris will convert it to ANT+ internals, apparently that is a slightly cheaper way of getting the more modern functionality than buying a newer hub up front.

Yes, I think it cost $250 to upgrade an older hub to a 15mm axle and the G3 electronics. So if you can buy an older SL or SL+ for a really good price, you can bring it up to modern specs.

This works really well, I'm running G3 electronics in my SL+ hub I bought new.

And IMO, the silver hub with the carbon inset is the prettiest one they've made.

Cheapest way to measure power?

Find a good long hill that's steep enough that you can only climb it under 10 mph/15 kph. And by long, I mean long enough to take at least 10 minutes to climb.

Weigh everything. You. Your bike. Your water bottles.

Time how long it takes you to do the climb.

Find the height of your climb. Use a topographical map, or your GPS if you have one.

Power (watts) = 9.8 * weight (kg) * height (meters) / time (seconds)

(One watt is one joule/sec. A joule is one newton-meter. Gravity exerts a force of 9.8 newtons per kg of mass.)

Wouldnt a wired PT hub get tangled in the wheel when rolling?

Least expensive way to measure watts ?
 

Assuming this isn't a joke, the pickup sits on the stay and is wired to the head unit. It's not wired to the hub.

I vote for the used Power Tap either wired or wireless. BTW, nice looking bike...really nice. I surprised nobody else mentioned that yet.

If you want just to establish a base line of watts find someone approximately your weight and as fit or more than you with a PM and ride beside them. Take note of HR and watts. Try it again a couple of months later to see if you are more fit. If you want to train with a PM follow the responses above.

Post #10 , supra.

OP asked about measuring power, not guessing at it.

You could also just go to a hotel gym with an old stationary bike that has a display with various metrics. I did that once and it told me I was holding 350+ watts for the entire hour I spent on it. It couldn't possibly be wrong. I also averaged 27 mph, seems legit.

Sir Wiggins? I had no idea you had a BF account!! :)

Don't get a wired powertap - spring for an ANT+ one. It's worth it, even if you have to save up a bit longer. The G3 is better still, because it's easy to replace the battery. Even one of those, used, shouldn't be that expensive - they can be had for ~$600 new with non-fancy rims when you find a sale.

You can rent a power meter for a week.

A lot of people are recommending used Powertaps, I thought used ones had some kind of problem, might not be reliable, etc? I don't remember the details but I was under the impression a used PT was more likely to have a problem than other used stuff. Am I off base?

What, if you don't mind me asking, are you going to do with the data? Are you looking to utilize it to train with? Or are you just curious as to what your output is?