ibike Power meter

NomadVW said:

I understand that there is a large group of folks that want the iBike for it's value as a lower priced training tool. If that portion of the community is glad to have it, I'm glad for them.

However, comparing power files from two separate riders - even on the same ride - is essentially useless based on someone's profile, ride position, efficiency in the group, etc... If they aren't side by side

I'm not saying that the iBike is useless, but it's important for people to know that it has definite limitations. I did my research before buying the PT SL back in October of last year, and while some of the "cons" have been fixed by firmware updates, some are not possible to fix because of the nature of the device and the way that it derives its power values.

I do often wonder how many people who have purchased the iBike have convinced themselves they like the device because that's the device they just spent $400 on.

Edited to add: As much as many convince themselves the PT is better in part because it costs more?

LOL! I wonder that myself! Great observation! It seems that both "communities" seems to stand behind their choice for the most part and maybe that's the real story here.

gene r

NomadVW said:

However, comparing power files from two separate riders - even on the same ride - is essentially useless based on someone's profile, ride position, efficiency in the group, etc... If they aren't side by side

I'm not saying that the iBike is useless, but it's important for people to know that it has definite limitations. I did my research before buying the PT SL back in October of last year, and while some of the "cons" have been fixed by firmware updates, some are not possible to fix because of the nature of the device and the way that it derives its power values.

I guess the question here is, is iBike good enough as a PM, good enough to function as a basis for power based training?

I don't yet have a PM but has been very interested in the various options out there. I see the potential advantage of iBike from angles of cost, weight, durability (no component wear) and portability. And if the PM reading is within 5-10% accurate, I'd think that's more than good enough for training in the scheme of things.

LT Intolerant said:

A friend on the ride uses a PT (and a polar)a nd it was interesting to get his AP/NP and compare it to mine for the 35 minute effort. His watts/kg were 3.3 AP and 3.99 NP, and mine were 3.26 AP, and 3.91 NP. Pretty darn close for a crappy power "estimator" IMO.

I don't have an opinion on the iBike, but I do have an opinion on this as a test of PMs.

There are two purposes for on-bike PMs: first, as a recorder of what happens during a ride; and second, as a guide for structured training. Or, riding "with" a PM (which in my case usually happens on group rides during weekends) vs. riding "to" a PM (which is what I do during solo workouts on weekdays).

I haven't been paying close attention to these threads but my cursory impression is that there is plenty of evidence that the iBike does well in the "with" category. What's needed is more evidence that it does equally well in the "to" category. IOW, if you're going out to do a structured workout, will you be able to manage that workout equally well with either PM?

Steve_B said:

You would be the exception then. I've seen it reported by others. I think you (Gene) are the guy that didn't like my poo-pooing the iBike on the NEBC list a few weeks ago. I haven't gotten around to getting back to you but I will.

another con: can't be used on a trainer or rollers because there is no "air intake" happening during this activity.

Any time you estimate something rather than directly measure it, you are introducing another set of variables that can produce even more error. People with Power Taps and SRMs have enough issues as it is, why make things more difficult on yourself? And don't try to tell me that you are measuring torque with an iBike because you are not.

I don't get where this idea that measuring the current across a strain gauge is somehow more 'real' than measuring the current across an accelerometer, etc. The iBike has the potential to have all the data it needs to calculate a power number just as hub, chainring, BB and chain vibration systems do. Whether the number it gives you is of value or not, depends on your requirements. - TF

RChung said:

I don't have an opinion on the iBike, but I do have an opinion on this as a test of PMs.

There are two purposes for on-bike PMs: first, as a recorder of what happens during a ride; and second, as a guide for structured training. Or, riding "with" a PM (which in my case usually happens on group rides during weekends) vs. riding "to" a PM (which is what I do during solo workouts on weekdays).

I haven't been paying close attention to these threads but my cursory impression is that there is plenty of evidence that the iBike does well in the "with" category. What's needed is more evidence that it does equally well in the "to" category. IOW, if you're going out to do a structured workout, will you be able to manage that workout equally well with either PM?

My experience has been that the iBike's works just fine for managing structured workouts, or should I say giving feedback during structured workouts. I'll use it during 2 x 20 LTs, at times glancing at "live power" or at times using the AP screen. For 5:00 vo2 intervals and short intense AC intervals I'll occasionally check live power. The device has a sub-trip feature so you see info, elapsed time, AP for that interval alone if you'd like.

The one complaint I have is that you can't see power and time on the same screen so you do have to toggle between the two, or what I do is put my Timex on my handlebars and use the stopwatch feature. I'd also love to have live TSS (like the Ergomo) but I've learned to calculate TSS (within reason) by using calories burned which the iBike does gives you.

I've only used a PT once and I would give it high marks as a device for managing a structured workout as well.

gene r

LT Intolerant said:

My experience has been that the iBike's works just fine for managing structured workouts, or should I say giving feedback during structured workouts. I'll use it during 2 x 20 LTs, at times glancing at "live power" or at times using the AP screen. For 5:00 vo2 intervals and short intense AC intervals I'll occasionally check live power.

Yeah, my a priori guess would have been that the iBike could do well for 2x20 LT's. The real question is, "what kinds of structured workouts, if any, are more reliably managed with one PM than another?" For example, we know single-leg drills aren't well-managed with the Ergomo -- but if you don't do single-leg drills, who cares? I suspect (but don't know) that the iBike wouldn't do well in sprint drills -- but if you don't do sprint drills, who cares?

Each PM has strengths and weaknesses for particular purposes. I think it makes sense to try to identify what those are.

The thing I cannot get out of my head is racing on a 1200g wheelset AND having a power meter. At $500 or so (assuming two extra mounts on different bikes) it makes it hard to stomach the same potential situation with an ergomo or SRM.

Terry Ferguson said:

I don't get where this idea that measuring the current across a strain gauge is somehow more 'real' than measuring the current across an accelerometer, etc.

Terry:

A non-negligible part of my real job (the one that pays me insultingly mediocre amounts) is explaining to people why not all mathematically or logically equivalent ways to calculate something give estimates of equivalent quality. To paraphrase Tolstoy, good estimates are all alike; every poor estimate is poor in its own way.

Compare apples to apples, and I'm not sure the argument that the iBike is a less expensive power meter is all that valid. By the time you pay for the iBike with cadence, a decent heart rate monitor and good software, you're probably going to be in the same price range as a new or slightly used PT SL and wheel on eBay. You'll also be paying about as much as the list price on the new Polar CS600 system. Once you have the kluged together iBike system, you'll still be without the ability to use it on a trainer, still have problems getting accurate readings in a pack or if you change position on the bike, and downloading and comparing HR to power data will be a problem.

The purpose of a power meter is to record and display useful data. Much of the most useful power data is developed and/or needed during competition. iBike can not record or display that data accurately or consistently and that's a big negative.

If 25% of your training is done indoors, iBike is useless 25% of the time. Consider the loss of useful data when riding in a pack might account for 25% more time when the iBike is useless, and the bottom line is that it's useless about half the time. Even if it works well the other 50% of the time, it's still no big bang for the buck.

Terry Ferguson said:

I don't get where this idea that measuring the current across a strain gauge is somehow more 'real' than measuring the current across an accelerometer, etc. The iBike has the potential to have all the data it needs to calculate a power number just as hub, chainring, BB and chain vibration systems do. Whether the number it gives you is of value or not, depends on your requirements. - TF

Estimating three of the terms of the equation of motion of a bicycle isn't close enough for many of us and ultimately, it's the torque you are putting into the drivetrain that moves the bike forward (on level ground) and not just three of the factors resisting your forward motion. (http://freewebs.com/velodynamics/guide3.pdf and go to page 28)

LT Intolerant said:

Interesting observation. I did a small group ride at lunch with 8 riders and lots of rotating and pulling through in really windy conditions on flat terrain. A friend on the ride uses a PT (and a polar)a nd it was interesting to get his AP/NP and compare it to mine for the 35 minute effort. His watts/kg were 3.3 AP and 3.99 NP, and mine were 3.26 AP, and 3.91 NP. Pretty darn close for a crappy power "estimator" IMO.

Though it's nice that the numbers were close, if you weren't riding side-by-side for the entire time (and you said that you weren't), then it's not a valid comparison. Also keep in mind that 0.04 and 0.08 W/kg can be a reasonably significant number of Watts in some contexts.

I have been using an iBike on daily commutes and training rides for over a year. I am on my second unit as I believe that the first one demonstrated some technical issues and was never properly functioning. I ride PowerTaps on my road bikes and decided to try an iBike on my commuter.

The iBike is a functional but truly quirky unit, that eats batteries and requires daily and often an as-you-ride calibration effort by comparison. I know guys who profess to buy their batteries for these units in blocks of hundreds. Riding the unit this winter on commutes, I could easily go through a battery every few rides. In some of the coldest conditions (for my part of North Texas) I would even be needing to make battery changes during my long rides.

Here is a brief description from an iBike user of what the manufacturer will agree that you will likely need to look at or do each time you ride:

Before each ride starting from home, I:

(1) Weigh myself, with bike and equipment, and enter the value in
Set Up;*
(2) Perform a tilt calibration; and
(3) Zero the wind off-set (a step which, I've discovered, is
extremely important for accuracy).

* When I ride home from work, I usually omit the weigh-in and
assume that my morning weight is "close enough."

In neither case do I perform a coast-down as part of my routine.
Just as John Hamann had assured me, since installing a standard
mount several weeks ago, I've seldom needed to do a new coast-down.
Any inaccuracies that I've experienced during that time have seemed
attributable to (a) cold weather; (b) failure to calibrate tilt
(particularly when removing and replacing the unit on its mount);
or (c) failure to zero the wind offset (particularly following
changes in weather). Hence the set-up routine above. When I do
follow this routine, however, my unit's readings are consistent and
seemingly accurate.

The biggest issue that I find in terms of data reliability is the unit's tendency to produce psychotically incorrect power spikes. Even with all the firmware updates and recommendations for use this is still an issue. The result is that these spikes dramatically skew your power numbers and related training calculations, especially when you use CyclingPeaks. Just a couple of these spikes a ride can really mess up your overall power profile. One time your max power output may be 1200 watts, another time it could be 2200. There is no rhyme or reason to it. But there is sure no way to train with that kind of screwed up data effect. The unit still has issues over rough roads too, which goes a long way to hender its inherent ability to translate rides into usuable and repeatable ride data. Take a look at the iBike forums and see what you think about the comments from some of the other users though, and gauge what you can live with on your type of intended rides.

The main frustration that I have had in all of this though is that for $400 a power device damn well better work the way that it says it will, and without a lot of calibration, on the bike and off the bike guess work and data interpellation. That has not been the experience with the iBike. Most of what you would now be using as guidelines for utilizing this device came from on the road users, not from the manufacturer, and apparently will continue to be so down the road. There are an amazingly large bunch of user who apparently don't have anything better to do than to do pro bono R&D for these iBike units. Truthfully, I am not one of them. If you are, you may well love this unit for that same reason.

My overall reaction to a properly functioning iBike Pro unit is that they don't perform nearly as easily and consistently as does a PowerTap. On the PowerTap you set it up, zero out the torque, and you get your ride data. Clearly PowerTaps can have torque tube issues, manufacturing defect issues, issues with keeping out the wet, and installation do's and don'ts too. Nevertheless, they are a ride-and-use device, without a lot of intrigue or voodoo. If you ride a lot, you will likely go through HR strap batteries every few months, a CPU battery a couple of times a year, and hub batteries about once a year. There really isn't much that you can do to influence the data output except via your pedals. And after a few years of training with a PowerTap, I can consistently guess within 10-15 watts of what I am generating just about every mile of a ride, solo, group, paceline, climb, you name it. The data it generates is that consistent, and lends itself well to that kind of on-the-road interpretation and repeatability.

Again though, everybody's training conditions, methods and expectations aren't the same though. The best advice that I can give is for you to do your homework and spend your money based upon what you can live with.

Now I have to go pee.

First, let me say that I admire the ingenuity and creativity of the team that created the iBike. I think everyone benefits when there is an expansion of possibilities and competition of ideas. I also like the possibility of roll-down aero testing.

That said, the issue of accuracy under all conditions (in a pack, out of a pack, certain situations that might through it for a tizzy such as Gene mentioned) is a big deal for me. When you consider that:

• most of us are looking at FTP improvement over the course of a year of probably <10% (mine usually changes less than 10% over the course of the year because I've been at this game for a while) and that week-to-week improvements are often in the single Watts, Power Tap's stated accuracy of 1 - 1.5% looks very attractive.
  
• as a racer, I have little control over the amount of people that I ride with
  
• I ride with various hand positions and in a fully aero position on a TT bike
  
• errors will accumulate over time and tend to make WKO+'s PMC less accurate
  

then I have big problems with the iBike for my own use, but "your mileage may vary", as they say.

Does anyone have any data on repeatability and reproduceabilty on an iBike, even under ideal conditions and also on a roll-down test?

What's so amazing to me is the "your power meter sucks and mine is the only choice" mentality of most iBike naysayers.

Many of the complaints that are levied against the iBike (i.e., flaky data, reliability issues, eats batteries, et al) have been levied against every power meter that riders discuss on this forum. My god how many my PT doesn't work posts have I seen in the past two weeks?

I've had one iBike unit, change the battery every 5 weeks, do a coast down and go. I don't need laser precision to train with power and to say that one can't measure/manage their training with an iBike is disingenous or an opinion born out of ignorance.

Insofar as "real cost" is concerned the comment about not having heartrate and having to buy sw is also misleading. It doesn't have HR today (and personally I don't want it even when they do release it) and when they do it probably means I have to purchase an $ 89 mount. On the software issue are not most using Cycling Peaks? So for $ 99 more I've got that solved.

I'm not sure why iBike bashers are so afraid of this little device/company. It makes no sense.

gene r

LT Intolerant said:

What's so amazing to me is the "your power meter sucks and mine is the only choice" mentality of most iBike naysayers.

I'm not sure why iBike bashers are so afraid of this little device/company. It makes no sense.

gene r

Gene,

Pointing out flaws is part of healthy discussion. If you wilt under hot lights, that's not our problem. It doesn't mean I hate you or the iBike.

In my job as an engineer, if I did not evaluate options based upon data, trade-offs, accuracy, cost and a whole host of other things, I would not have lasted 20 years in the electronics industry. I would have been out on my ear a long time ago. While not all decisions in my personal life require the same level of scrutiny (or accuracy) as what I do at my job, blindly accepting marketing spew would seem to be a perilous course to take too. When you're going to plunk down a few hundred to several thousand $ on something, spending some time finding out the real pluses and minuses from real people would seem to be an intelligent course to take.

I also didn't say you can't use it. I simply said I had my reasons why it doesn't seem suitable for me. Consider the meaning of "your mileage may vary" one more time. Also, scroll up a little and you'll also find that I stated, "PT and SRM users have enough problems as it is..." Consider the meaning of that too.

What I also think is interesting is that the tech person (sorry-I for got his name) I spoke to yesterday was very frank and said there will be times when the iBike will drive you nuts!!

he offered some other interesting thngs that you can do with an ibike that you cannot do with a PT< SRM< Ergo. You can (in very perfect conditions!!) do coast down tests to determine advantages in any number of different things from position to air pressure, tires, wheels, aero bars, clipons, elbow pad width, etc.
Also, it is possible while drafting in a pack to use the data on screen to find a spot in the draft that provides the least wind resistance. This could be helpful while riding into cross winds (to establish the best direction or angle for the echelon to take).

For a real bike geek (not an insult) with more time than most of us have, this could be a really fun toy!!

Ray

Steve_B said:

Gene,

Pointing out flaws is part of healthy discussion. If you wilt under hot lights, that's not our problem. It doesn't mean I hate you or the iBike.

In my job as an engineer, if I did not evaluate options based upon data, trade-offs, accuracy, cost and a whole host of other things, I would not have lasted 20 years in the electronics industry. I would have been out on my ear a long time ago. While not all decisions in my personal life require the same level of scrutiny (or accuracy) as what I do at my job, blindly accepting marketing spew would seem to be a perilous course to take too. When you're going to plunk down a few hundred to several thousand $ on something, spending some time finding out the real pluses and minuses from real people would seem to be an intelligent course to take.

I also didn't say you can't use it. I simply said I had my reasons why it doesn't seem suitable for me. Consider the meaning of "your mileage may vary" one more time. Also, scroll up a little and you'll also find that I stated, "PT and SRM users have enough problems as it is..." Consider the meaning of that too.

Not wilting (or taking this personally), I just feel that some of the comments about the iBike misrepresent the efficacy of the device vis-a-vis other offerings in the space. I've also said all along that YMMV and that the iBike is not for everyone.

gene r

Hey, exactly ray! I can see that a lot of iBike users are really enjoying tinkering around with their units, mounts, and uses. A lot of what they are doing is pretty passionate and inspired.

And gene, truth is that you can take an iBike, go ride it on chip and seal, over rough road, in a pack, or in high cross wind situations with a lots of cornering and get complete shiznit for training data. If iBike had done a much better job of being upfront about the issues with their units, I think that a lot of the user commentary that they get in these threads would be more forgiving.

The smart money may well be to wait until the iBike Pro 2 or future version comes out that takes all of the current user R&D into account. That unit might stand to do a lot of things better than does the current unit.

rayhuang said:

Also, it is possible while drafting in a pack to use the data on screen to find a spot in the draft that provides the least wind resistance. This could be helpful while riding into cross winds (to establish the best direction or angle for the echelon to take).

You can do that with a power meter, not just the iBike. I did this recently while riding in echelons in Arizona (with a Power Tap).

One potential benefit of iBike, regardless of it's efficacy as a training tool, is that it may cause others to enter they fray and offer more reasonably priced alternatives. Let's face it, measuring torque isn't new technology, it's just found a new application. Personally I think the prices for a PT is a way to high.

Maybe a price correction here will lead bike companies to start offering PM's as standard on higher-end bikes. That would be nice......