Lacking

FTP and W/kg

Hello I have just two questions to being with.
1) I do not know what FTP actually is, so will someone could help me out there?
2) How can you test your ftp or w/kg if you do not have something like a powertap or cycleops?

I know some of you more financially blessed people out there have power taps and such but seeing as I am new to the sport I cannot afford these luxuries quite yet in my career. I was just wondering if there is anyway I could get my statistics tested for the start of my first race season? I would like to compare them to the end season as well as have them for a start point for next year.

dstrong 

File Transfer Protocol (FTP) is a standard network protocol used to exchange and manipulate files over a TCP/IP based network, such as the Internet.

Lacking

Oh! I thought it was an entirely different acronym. That was my bad on that.

Jynx

FTP is Functional Threshold Power. It is the max power you can sustain for approximately one hour.

Lacking

That is what I thought it was! Could I possibly test for this with just a speedometer and a cadence counter? If so could someone leave a link to relative performance expectations with certain time/cadences, it would be much appreciated. If such items does exist for general comparison.

Flatballer

no. You need a power meter to test for power.

johnybutts

If he has a very steep hill that lasts for more than 20 minutes he can approximate it

Grumpy McTrumpy

Why on earth would anyone be interested in power numbers if they don't use a power meter for training? If you want to compare dicks then just sign up for a race.

clausen

There are to many variables you can not approximate power output .

vampares

Power output equals speed (for all intents and purposes) . To compare just do one ride and then the same thing again. If you are loosing weight, bring it with you (or not if you want credit for that). Overall it is a better measure of strength.

You'd really need a power meter if you were in danger of over extending yourself.

Flatballer

You've been here 4 years and apparently still don't know WTF you're talking about.

Maybe wait another 4 years and try again.

vampares

I'm going to buy you a power meter and make you use it.

Flatballer

I already have one. But I'd love another. I'll take a Ptap in a Zipp 404.

clausen

If done under perfect condition, what you are comparing and all you can find out from that test, is if there was a change in power output between efforts. That does not tell you how much power your putting out.

challaday

Beg or borrow a powertap from someone if you can. There's absolutely no way to calculate power without a powermeter, at least on a bike. I've loaned my ptap out to friends who wanted to do the FTP test. Makes for interesting conversation when you compare off the e-wang chart.

umd

No, johny is correct, on a steep hill if you know the weights and the distances and grade (and wind if there is any) you can get a really good approximation. I've tested this several times and the results have been consistent. Climbing, the greatest force you are working against is gravity, which is constant. Not climbing, aerodynamics are much more important and it is very difficult to know your coefficient of drag with any reasonable accuracy. Also at greater speeds rolling resistance is more important, and that can also be difficult to pin down. But also Grumpy is correct and there isn't much point if you aren't actually training with a power meter. I did this a bunch when I was on the verge of getting a power meter, but the results weren't useful for much other than idle curiosity.

umd

Also, read this thread and all your questions will be answered

https://www.bikeforums.net/showthread...-comments-here

umd

All aboard the failboat!

umd

Damn, I hate when people serial post

Mark Kelly 

If all you want is an estimate of power output, all you need to do is ride up a long hill and apply the formula

Watts = velocity x slope x mass x 10 + velocity x mass / 20 + velocity^3 / 8.

with velocity in m/s, weight in kg, slope in percent.

To get reasonable accuracy you need a new calculation each time the slope or your speed changes. If you have access to a nice long hill that has a consistent slope the accuracy is not bad at all. Not far from where I live there's a mountain climb which is 17 km at a pretty consistent 6% grade: the last hill on this profile:


Once you get in your rhythm on this hill you can sit at the same cadence in the same gear all the way to the top.

It's not as accurate as a power meter but it's a lot cheaper.

milliron

Near me, there is a tri-geek training place that will toss a PowerTap wheel on your bike, set you up on a trainer and yell at you for 20 min while you spin your ass off.

Also, another LBS has a set of PT wheels that they rent.

I like numbers. I think FTP test is a nice way to check your performance and verify it's increasing. Good for motivation.

umd

Most people don't put out as much power on the trainer as on the road.

clausen

I know it can be calculated. I'm surprised your results where close, last time I tried figuring it out from gps file, the results where off close to 10 % when compared to a power meter file. It was windy day, climbing out of a valley. Lots of room for error.

umd

I don't know about "from a GPS file," and a windy day will screw it up too. But if you have a consistent known grade, it really is just physics. However trying to calculate a whole ride the conditions are too variable, or on the flats aerodynamics becomes too important.

RoboCheme

That's correct. After I got my PT, I put it on the trainer and did the 20 minute FTP test. I averaged a whopping 150 watts. I later did it on a hill and averaged 217 watts. Still pathetic, but less so.

If you've got a hill where you know the average grade pretty well, this calculator works pretty well.

https://bikecalculator.com/index.html

Once you calculate your FTP, what are you going to do with it without a powermeter?