fa63

I did a quick review of the iBike Sport Gen3 and posted it on my blog; I figured some on here might find it interesting:

https://ft-atalay.blogspot.com/2011/0...rt-review.html

I am not sure exactly how accurate or up-to-date the Allen & Coggan race category table I refer to is, but I found it interesting that the numbers match my perceived abilities fairly well. There were some heated discussions a while back about the iBike's accuracy and/or usefulness, but based on my limited experience with it so far I think it will make for a very useful training tool (at least it seems consistent), especially given its price ($200). Let me know if there are any questions and I will do my best to answer.

P.S. I have never used the PT, SRM or Quarq power-meters before.

kleinboogie

I don't even need to look. A device that measures everything but power is not worth my time and definitely not my money. Good luck with it. If it keeps you riding that's a good thing.

echappist

Sorry to be harsh, but if i'm spending $, the thing better be a measuring, not estimating device. Especially consider that you can get a real PM for a few hundred dollars more... The one that does aero measurements is $650.

This iBike sport model won't even allow you to d/l data, and the one that does is $500. I got my ptap wireless SL+ used for $560.

waterrockets 

This argument is a red herring, but a "measuring power" categorization is up for debate. Also, don't discount the iAero's potential for drag measurement when used with a torque-based power meter.

kleinboogie

When the iBike actually measures Force I'll give it a second look.

I actually like that aspect maybe coupled with a power meter. I hope Andy's Chung-On-A-Stick comes into existence. Cheers

rruff

It has a very good accelerometer. F=ma you know.

The issue isn't whether the iBike "measures" power or not... it does as much as any other PM. The issue is how far it deviates from reality and how often. The way it determines power relies on an accurate measurement of several variables that are quite difficult to get right... especially if it's windy, you are going downhill (ie fast), or the road is rough. Errors tend to even out though, if it is properly calibrated and you use the post processing.

Homebrew01

Another benefit of a real PM is that you can use it on the trainer.

Bob Dopolina 

Incorrect.

It doesn't measure power. There are no strain gauges. It calculates power based on a series of assumptions.

For the price you'd be better served by a downloadable HR monitor.

fa63

I didn't mean this thread to be one along the lines of "iBike works just as good as PT/SRM/Quarq for a fraction of the price". I just wanted to share my experiences with it so far, and while it is not perfect, it seems to be very consistent under most conditions I have encountered so far. I think consistency is the key when trying to gauge improvement, so I am not too concerned if the readings are off a little bit as long as they are consistently so. I would actually love to put it next to a PT and see how the two compare (Velonews found them to compare very well, for what it is worth).

I bought the base version to give it a try and see if it was worth a damn, and so far I think it is worth the price. I am actually thinking of upgrading to the Pro version soon to have the ability to download and analyze the data. As it was pointed out, it gets somewhat expensive once you want to upgrade to the Pro version ($200 for the upgrade, on top of the $200 I paid for the base unit to begin with). But I think other riders/racers on a budget will find even the base version (which I think is reasonably priced, although other's idea of what is reasonable may be different) a very useful traning tool.

With that said, I should note that I haven't owned the unit long enough to assess its durability. Everything I just said will be meaningless if it doesn't hold up, and from my experience Velocomp's (iBike's maker) customer service was OK but not great. So I am hoping I won't have to use them again

WonderLake

Uhh, nope.

Homebrew01

How can you tell ? If riding the exact same course multiple times, but each with different combinations of wind conditions, barometric pressures and temperatures, how can you know if it's giving you an accurate "power" reading ?


Personally, I would always be wondering if the numbers were right, did I calibrate it properly this time ....
even if the overall numbers from a ride are similar to powermeter numbers, the short interval feedback from a pm can't be matched.
And since their top model is about the same price as a powertap, the choice is pretty clear to me.

RChung

I completely agree with this.
Can you do post processing with an iBike Sport?

aggro_jo

Well said. The old 305 does great at measuring/recording what it supposed to without pretending to be a power meter. When/if the time comes where an athlete wants to train with power, powertap is the clear choice.

RChung

Me too.

tombailey

I ran one side-by-side with a Quarq and got MOSTLY matching results. The iBike lagged behind on short/sharp efforts and in some other situations. The big problem is that when it was off (due to weather or whatever) it was way off and often stopped working. Also the constant calibration to make it work, and the fact that it doesn't really work on the trainer are a pain. I don't think it's that bad, but I wouldn't buy one.

fa63

Good question; my opinion of the consistency of the unit is based on these:

- The numbers shown on the screen do not jump around significantly when I am doing a steady effort, including when I am riding over not so smooth roads. Obviously, an increase in effort, whether it is from riding into a headwind or some other factor, results in an increase in power.
- The average power from riding my favorite 20-mile course in what I would consider similar conditions has been consistent. I also went all-out once which resulted in a higher average power than usual. I should note that there are no stops so my times when I am riding solo are very consistent on this particular course.

Again, these do not prove the accuracy of the unit, by as I said before I am not worried about absolute accuracy as long as the conistency is there.

By the way, the calibration is done once and the unit goes through an auto-calibration, which takes about 10 seconds to complete, every time it is turned on. So there is no hassle there.

I will agree with you that the iBike is not going to be very good in tracking short-duration (I would say, 5 seconds or less) efforts because there is some delay between putting the power down and seeing the numbers jump.

echappist

Sorry, but that's the one thing that should be jumping by +/- 20W due to the uneven resistance encountered in cycling, even if your speed is even, and the terrain looks "even." That the estimated wattage doesn't change dramatically is probably due to the fact that the unit isn't sampling very fast and that the computer compensates by running a rolling average with a long decay constant.

One of the first things you realize when you get a real powermeter is how much the number jumps, even with a 5" rolling average.

fa63

I said it doesn't jump around significantly; of course the numbers jump around a bit. I have no idea what the sampling rate is, but I would be surprised if it is much slower than a PT.

rruff

And other PMs calculate power based on a series of other assumptions. They both rely on physics.

rruff

No... you have to be able to download.

rruff

IME the reality of using the unit is the other way around. With post-processing I can get an AP for a ride that is within a couple % (probably). But in real time, it can vary a lot. Crosswinds, rough roads, and fast descents seem to be the worst case. Also, if there is significant drafting, or the wind shifts then the post-processing doesn't work so well either.

aggro_jo

just read the blog. More disturbing than the thought of using the iBike as a power meter is the idea of doing a 20 minute test on a MUP.

echappist

You missed the point. Point being it SHOULD jump significantly if you look at the file. That's the first thing you realize when you get a powermeter: how much jump there is in the data. On a flat road on which i'm averaging 240W, i can expect to see variation between 200W to 300W. See below. Note how the speed really doesn't deviate much.


And it just so happens that training by power is most useful for efforts at and above VO2 max, for which HR and other indicators are not that reliable. I guess it would work great for triathletes though as their race is at tempo pace and the most intense stuff they do is at FTP range.

RChung

Yeah, not being able to download is a deal killer. My first experience with PMs was a bit more than a decade ago when I had one of the original Power Tap Prologues on a couple month long loan. Like the iBike Sport, that model wasn't downloadable. People who know me can understand the deep irony of me having a PM that I couldn't get the data out of. However, even for less-OCD users than I, the ability to review, summarize, store, and share the data collected on rides is pretty important.

fa63

Why is that?