iBike power meter

[_Daemon_]

Saw this at the 94.7 expo, had a brief look at it before I had to run off. Looks quite interesting, measures your power output based on speed, and wind and gradient etc. etc. etc. something along those lines, so no need to built a special hub into a wheel or get a special bb etc. etc. Anyone got anymore info about this device?

[gianni]

and you can't use it on your indoor trainer and still quite a few questions about it.

 

it works on air flow so anything impeding / influencing the air flow will affect the accuracy of the power readout.

[_Daemon_]

never mind....just read the powertap thread and saw the ibike posts. Guess the std powertap is better option.

[BikeMax]

Yes - be careful if you are looking for an accurate power meter.

 

Issues withe the i bike include;

 

1. needs regular calibration due to the fact that the frontal drag affects the reading - if you change position on the biek the power will vary (from hoods to drops for example)

 

2. Misreads in bunches due to the effect the draft has on the wind speed accelerometer

 

3. Does not like rougher surfaces and drops power - resulting in skewed averages

 

4. There have been lots of reports of the unit moving while riding - leading to power misreading

 

They are apparently addressing these issues slowly but the method for calcualting power (not reading directly) is flawed.

 

In general, it is a compromised device and a PT std comes in at not much more money for a reliable and accurate device with great back up

 

I am in the business, and and am a big Power Tap fan and hence have looked these units carefully.

 

[GoLefty!!]

Taken from the www.cruciblefitness.com forum, a retort by John Hamann one of the founders of the iBike Power meter.

 

The Link:  http://www.cruciblefitness.com/forum/topic.asp?TOPIC_ID=3701

 

Just thought I'd balance the views by adding in commentary from someone with a vested interest in a product other than Powertap.

 

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Hello everyone:

My name is John Hamann and I'm one of the people responsible for the new iBike Pro power meter that is the topic of this forum.

I'd like to respond to some of the comments I've read on this thread. For those of you who subscribe to the Slowtwitch forum, you?ll see that many of my comments here are paraphrased.

I?d like to start by saying that the iBike Pro is a very serious product. We are avid cyclists ourselves and we have the same high expectations and standards for this product as your comments reflect.

Most certainly, we did not design the iBike Pro to ?guesstimate? power. We fully understand that accurate power measurement is not a trivial matter. But we also know that there is more than one way to measure power accurately. Competitive units measure the forces applied at the pedal. We measure the forces opposing forward motion. According to Newton, applied and opposing forces must always be the same. [Golefty - See Bruce, not equal to zero, EQUAL, therefore Fi = Fmu + Fd < gedit?>]

So...our approach is as "direct" and mathematically accurate as any other.

In fact, the opposing-forces approach provides an innovative, accurate, and cost-effective way to measure power accurately.

Now, to some of your specific points.

We tried to make calibration extremely simple..., tilt: turn the bike 180 degrees; coast-down: stop your pedaling after you've reached 20 mph. Both procedures are simple and fast (about 1 minute to do both procedures). These two procedures calibrate the tilt sensor and determine the aerodynamic and frictional drag coefficients for your particular bike set-up and riding position. (You'll be able to see your actual drag coefficients using the included software). At Interbike some of the techies likened this to a poor man's wind tunnel.

In fact, when you compare the iBike set-up to competitor power meter set-up (new wheels, cranks, chain magnets, wires, wires, zero offset, etc) we think this is pretty simple.

The big "bomb" people love to throw at the iBike is the change-riding-position argument.

It is true that changing riding position can affect the aero watts reported by the iBike. But here is a very practical question: if you change riding positions WHY have you done so? If you're on the flats going 25mph I guarantee that you won't stand up for very long! What does that mean with respect to iBike measurement accuracy? Suppose you're riding on the flats at 200W, and that you stand up 3% of the time. When you stand up let's suppose the iBike under-reports aero watts by 25% (you're going fast!). At the end of the ride you'll find that your average watts "error" will be only 1.5%, well within the accuracy of competitive products.

On a technical course where you're changing positions due to hills or terrain, you're not going as fast (you're probably working VERY HARD due to hills), so aero watts aren?t a significant portion of your total power output. For example on a hill where 80% of your total output is going toward hill watts, 15% to aero watts, and 5% to friction watts, then a 10% error in aero watts measurement (due to riding change position and lower speed) causes only a 1.5% error in total watts.

Is paying an extra $1000 to $4000 to get a theoretical 2% accuracy improvement during the 5% of your ride where your riding position is different really worth it?

Concerns about accuracy beg an obvious question: do the accuracy claims of other products account for errors caused by drop-outs, failures in the rain, wrong zero offsets, and drift due to temperature changes? We suspect not, but these are significant accuracy and consistency issues that are a direct consequence of their measurement technology. The iBike has none of these problems.

 

[Golefty -  Powertap does drift and theres vokall I can do about it. Unless Bicycle Power can develop metal strain gauges unaffected by a change in temperature. If anyone knows of this wonderous technology then please share but on the planet i live on, metal expands with temperature and it's resistance changes as a result.]

The sensors we use are extremely accurate and sensitive (they are unique to the iBike). [Perhaps some marketing BS here...]Some of you have experience with barometric pressure altimeter devices; we agree that these have response and accuracy issues. That's why they guesstimate and that?s why we DON'T use that measurement approach.

We have designed the iBike so that our measurement errors do not add linearly. Without getting too technical, suffice it to say that a 1% error in aero watts, a 1% error in hill watts, a 1% error in acceleration watts, and a 1% error in friction watts do NOT combine to a total error of 4%. In fact, for the conditions described above, the correct answer with the iBike is that the total watts error would be only 1%.

[some statistics, first year Engineering math if I remember correctly]

Trainer: When we introduced the iBike Pro at Interbike we clearly positioned it as a power meter for outdoor bike usage only. That said, we have had many, many requests for trainer capability for the iBike. We've given it some thought and we think there may be a way to do it. Needless to say, we're busy getting the basic product to market right now, but we hope by the Fall to have a (cheap) answer for all of you who have bought iBikes and want to use it during the winter on your trainers.

Test results: last year we tested an iBike prototype against the PT we own. We were really pleased...in fact, we were astonished by the comparative results; it's what made us decide to go to market. We also decided that we would not post any comparative results publicly except with a full-production unit, because that is the unit you will be using on your bikes. So, as soon as we have production units available (any day now) we'll put THOSE on our bikes, and we'll post those results on our website. Then you can see why we have been so excited for so long. And by the way, we now own a $3,000 SRM too...

Cadence: Cadence is coming! To add cadence capability to the iBike all you will need to do is change handlebar mounts. The cadence handlebar mount contains the sensors and electronics needed to report cadence. Once you install it your existing iBike will report cadence.

We expect the cadence handlebar mount to ship very soon after the iBike ships.

And by the way, Heart Rate handlebar mounts are on the way, too.

We respect your skepticism but within a month you'll see iBikes out on the road. And if the device works as promised you'll have a really cool new way to help you become better athletes.

Isn't that what you want?

John Hamann

 

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What I love about this product is that the company marketing it are constantly improving it and adding upgrades, some for free, some at a cost. The people at Powertap simply redesign the unit evertime they make a change to keep you buying it. The pending wireless version is a case in point.

 

Hopefully soon, iBike will have an version that will be switchable from Road bike to MTB. Then the powertap wheelset will be up for sale

 

I know which Power meter I'll be buying when the Powetap's lifecycle comes to an end.

 

It won;t be another Powertap.

[bruce]

 

GoLefty!!!  If you remember engineering mathematics, then you will remember the fact that a force is a vector.  And that the SUM of the forces equals zero because the forces are in opposite directions when an object is moving with constant velocity.

 

Once again:

Force = mass x acceleration.

 

If an object is moving at constant velocity, then acceleration = 0, hence the resultant force on the object is zero, because the force VECTORS cancel each other out.

 

This is the fundamental principle that the iBike uses when calculating the force that a rider is producing is equal in magnitude, but opposite in direction to the force that he is overcoming.  If this was not true, the rider would be accelerating infinitely!!

 

Please tell me that you can comprehend these fundamentals.  If not, then please stop arguing them.

 

[Spinnekop]

O kots.  My popcorn is klaar.........

[bruce]

Spidy, better get some more - my blood pressure is maxing out here!!

 

 

[BikeMax]

 

Taken from the www.cruciblefitness.com forum' date=' a retort by John Hamann one of the founders of the iBike Power meter.

 

The Link:  http://www.cruciblefitness.com/forum/topic.asp?TOPIC_ID=3701

 

Just thought I'd balance the views by adding in commentary from someone with a vested interest in a product other than Powertap.

 

-

 

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What I love about this product is that the company marketing it are constantly improving it and adding upgrades, some for free, some at a cost. The people at Powertap simply redesign the unit evertime they make a change to keep you buying it. The pending wireless version is a case in point.

 

Hopefully soon, iBike will have an version that will be switchable from Road bike to MTB. Then the powertap wheelset will be up for sale

 

I know which Power meter I'll be buying when the Powetap's lifecycle comes to an end.

 

It won;t be another Powertap.

[/quote']

 

Thanks for posting that - anybody that took the time to read the whole thread will most likely not be buying an Ibike anytime soon - guys like Tom Hampton are seriously well informed and make some very good points not only before but in response to John Hamman's marketing spiel.

 

[Spinnekop]

Bruce.

Brannewyn en Coke boet......Goes GREAT with salt & viniger popcorn!! 

 

At least admit that for a peanut like myself with NO powermeter, the iBike thingy would be a stunning tool to help me go a little bit more and harder than what I am doing now....?

 

 

 

[BikeMax]

 

 

Please tell me that you can comprehend these fundamentals.  If not' date=' then please stop arguing them.

 

[/quote']

 

You are wasting your time Bruce - Lefty is out of his depth here IMO.

 

Maybe it's because you are talking out of your a..e again and he doesn't speak that language..

 

[BikeMax]

 

What I love about this product is that the company marketing it are constantly improving it and adding upgrades' date=' some for free, some at a cost. The people at Powertap simply redesign the unit evertime they make a change to keep you buying it. The pending wireless version is a case in point.

 

[/quote']

 

Perhaps that is because the basic product is based on sound principles and works as it should - it does need constant tinkering and upgrades in order to address the issues that should have been sorted pre release.

 

[bruce]

 

Bruce.

Brannewyn en Coke boet......Goes GREAT with salt & viniger popcorn!! 

 

At least admit that for a peanut like myself with NO powermeter' date=' the iBike thingy would be a stunning tool to help me go a little bit more and harder than what I am doing now....?

[/quote']

 

Any tool that enables you to measure the power you produce is better than no tool, absolutely 100% correct.

 

Is it the best powermeter - I personally believe that the SRM is the best powermeter - can't afford one of those, so I make do with what I can afford.

 

It would take a lot for me to trash anybody's product.  All I will do is try to point out the FACTUAL strengths and weaknesses so that people can make informed decisions - because even the iBike is not a cheap product, and if it doesn't meet your expectations it adds around R5k to the next PM that you purchase.

 

Eish, good thing I don't do HR training anymore - I think I've just done an anaerobic interval!!

 

[gianni]

HR is useless anyway ;-)

 

ops..another can of worms opened up!!

[BikeMax]

 

Bruce.

Brannewyn en Coke boet......Goes GREAT with salt & viniger popcorn!! 

 

At least admit that for a peanut like myself with NO powermeter' date=' the iBike thingy would be a stunning tool to help me go a little bit more and harder than what I am doing now....?

 

 

 

[/quote']

 

You either spend R5.5k on an Ibike with cadence or R6k on a PT Std with wheel.

 

[bruce]

Hey gianni, pop over to the "Most Sensitive Topic for 2006" thread and stir up a storm there!!