"The 33"-Road Bike Racing - IBike Generation III (Cross post from Road Cycling)

I've been curious about the IBike since it's a lot cheaper than the other powermeters around and it claims to be as accurate (the basic unit is 430 bucks brand new). I emailed tech support a few questions and this is what they came back with.

I've been eying powertaps lately, but I think I might try this one out instead if/when I get a PM. The concept seems pretty cool and someone who I was riding with seemed to really like it and they had the 2nd generation.

Here goes...



Question 1) I had heard that earlier models had a problem with giving whacky
readings on bumpy roads, is this still the case?

Answer 1:
1)No. The new models are 5 times more vibration resistant than the GEN I
iBike. In fact, as the person who handles all the technical support, this
problem was all but eliminated with the GEN II models. GEN III will be ever
better. Just make sure you mount the unit correctly.

Question 2) How do you do the coast down if there are no flat roads that are 4
miles long?

Answer 2: I think you're referring to the 4 mile out and back. The coast downs only
require about 50 yards or so to do. You just pedal up to 20mph and then
coast down to 8mph and the iBike measures you're frictional and aero losses.
The 4 mile out and back can be shortened some if you can get a relatively
flat course, but it must be an out and back (it's measuring your riding
tilt). The course doesn't need to be perfectly flat either, just don't pull
or tug on the bars. The new unit will also have a input profile based on
height, weight, etc. that the guys over at DLP racing (they do a lot of
testing for us) say comes extremely close to the actual profile builds.

Question 3) The ibike works by making calculations based on the airflow coming
into the unit, how does drafting affect this? Does the Ibike drop
readings or give funky readings during pack riding?

Answer 3: In pack riding the iBike performs quite well. This is because both you and
the iBike will receive the benefit of the draft regardless of the height
difference. Your whole body receives the draft in the pack. The iBike will
over compensate one you're riding behind just one other rider (not in the
pack) because it's likely that your head will not receive the draft but your
body will (where the iBike is mounted). It will be less than a 5% difference
from my experience.

Question 4) Is the instantaneous power (i.e. 5 second power) accurate on the
ibike? I'm asking since the power being applied is higher than the
windspeed would lead a unit to believe during the start of a sprint,
unless the rate of change of windspeed is also going into the calculation.

Answer 4: Wind speed is always a part of the iBike power calculation. I think the
iBike has very accurate instant power readings. The only problem I've seen
in very violent sprints is that the rocking of the bike can cause the slope
to go down and reduce the power numbers slightly. I've never heard anybody
really having a problem with this as the loss is minimal.

I just heard back from them again that the device can be used on the trainer with a wireless sensor and firmware upgrade. If you buy all of this together, it costs 737 instead of 430. It's a bit more expensive but still much cheaper than any other new powermeter. The 737 dollar unit also has HR and such.

The basic model for 430 doesn't have HR either.

The IBike III is also compatible with the 705 and quarq.

Brochure for anyone interested. (http://www.ibikesports.com/Final_iAero_iPro_Brochure.pdf)

I think you should be able to find a used power tap for around that perhaps.

The PowerTap never leaves me wondering if its right. I've seen PTSLs for $450 used, not built. So, for about $550 you could have everything.

Regarding the losses on the 5s power, I believe that an accurate power profile is important to assess your race limiters. If it's short-changing you "a little" on the sprints, the you really don't know where you are.

Different riding positions will also impact the readings. I spend a little over half my time in the drops. So what position would I calibrate it too, drops or hoods? One bottle or too? My tight jersey or my looser one?

That said, the ibike is an amazing device, and I do believe them that it's gotten a lot better. One thought is that getting an ibike with the later intention of getting an ANT+Sport power meter might make sense. If you combine the ibike with a Quarq, SRM, or 2009 PowerTap wireless, you've got a portable wind tunnel, that's really accurate. That's just cool.

hmmm - you could find out the best position of aerodynamics to power ratio. That'd be killer I think - especially for TT's.

Yeah, torque-based power meter + ibike = killer app.

Ive been using the ibike since the Gen 1 came out. It has gotten much better. The Gen 2 is a huge improvement. I vibration issues are no more, and once I figured out how to calibrate and use it properly its been a great unit. The best part is when they come out with a new unit you can upgrade for a fraction of the cost. So my Gen 1 I paid $300, and the Gen 2 upgrade was $199. So for $500 I got the Gen 2. I have HR and wireless. With extra mounts I just swap it from bike to bike. Is it the best unit? Maybe not. Does it work?Absolutely. Ive considered a powertap from time to time. But like Waterrockets and his bike, Ive just seen no real reason to spend more money.;)

I think the biggest problem with the iBike up here was the high % of chip and seal roads. Too rough for the iBike. Maybe it works better in more urban/suburban areas with smoother roads. But the calibration really was a huge pain.

I think the biggest problem with the iBike up here was the high % of chip and seal roads. Too rough for the iBike. Maybe it works better in more urban/suburban areas with smoother roads. But the calibration really was a huge pain.

Boy,... what a difference in tone between this post and the other cross-post. In that one, the venom was overflowing.

But, you've been singing the same old song about this device for the past three years without having used any of the new ****. We could all point at Apple I in the same way--that device has not much in common with the current Macs. Pencils suck in comparison to CAD software. Rocks are not as effective as bullets.

So, maybe until you've used something current, you should just shut your friggin' mouth about it.

Actually, I really don't care what you use. What I do care about is when someone talks about something as if they are an expert, but they aren't up-to-date or have even used the -whatever-.

So, step out of your Mercury capsule... they use space shuttles these days.

That is all. [UNSUBSCRIBED]

Paraphrasing my post in road cycling:

Used PTaps ftw.

The PowerTap never leaves me wondering if its right. I've seen PTSLs for $450 used, not built. So, for about $550 you could have everything.



I've only found the powertap to be reliable when the temperature is fairly constant throughout a ride. I regularly have cases where the temperature drop from riding in the sun to riding in the shade will offset the zero torque point enough that it cannot auto-correct.

May as well repost my reponse from the other thread...

"I'm not saying that the iBike can't be useful, but it is not internally consistent because it is so position dependent. I wouldn't go so far as to say that they suck, but anybody that thinks they are as accurate as other power meters is delusional."

I agree though that using an iBike as a head unit for another PM and combining the data could be really cool.

Boy,... what a difference in tone between this post and the other cross-post. In that one, the venom was overflowing.

But, you've been singing the same old song about this device for the past three years without having used any of the new ****. We could all point at Apple I in the same way--that device has not much in common with the current Macs. Pencils suck in comparison to CAD software. Rocks are not as effective as bullets.

So, maybe until you've used something current, you should just shut your friggin' mouth about it.

Actually, I really don't care what you use. What I do care about is when someone talks about something as if they are an expert, but they aren't up-to-date or have even used the -whatever-.

So, step out of your Mercury capsule... they use space shuttles these days.

That is all. [UNSUBSCRIBED]

Pencils to CAD software? Has Gen III figured out how to automatically adjust power readings between riding on the bar tops compared to riding in the drops?


I've only found the powertap to be reliable when the temperature is fairly constant throughout a ride. I regularly have cases where the temperature drop from riding in the sun to riding in the shade will offset the zero torque point enough that it cannot auto-correct.

Yeah, I haven't seen that. Maybe we don't have those kinds of temperature swings though.

hmmm - you could find out the best position of aerodynamics to power ratio. That'd be killer I think - especially for TT's.

That's what the IBike Aero is for. It's a real time drag measuring device. It's also a lot more (about 1k ish). It's in the brochure that I posted and looks pretty cool.

Pencils to CAD software? Has Gen III figured out how to automatically adjust power readings between riding on the bar tops compared to riding in the drops?



Yeah, I haven't seen that. Maybe we don't have those kinds of temperature swings though.

Shoot them an email if you're interested in the technology. They got back to me twice in a few hours. Since you torque the bars differently in each position, theoretically it should be possible to measure the flex, i.e. tilt of the unit in the horizontal plane of the bars (i.e shifter to shifter) and use that to see where you are.

The test in the past for calibration was done in your most aero position. So you'd have to redo it if you swapped stems or flipped a stem and such. Doesn't seem like too big of a deal.

The team that's using them has measured them against other power meters and seem to think that they stack up pretty well. Then again, they are sponsored, but they have provided data.

Edit: Email for tech support is atimmer@velocomp.com

PM curveship. He has done quite detailed testing on his iBike and I'm sure would be happy to pass along the results.

May as well repost my reponse from the other thread...

"I'm not saying that the iBike can't be useful, but it is not internally consistent because it is so position dependent. I wouldn't go so far as to say that they suck, but anybody that thinks they are as accurate as other power meters is delusional."

I agree though that using an iBike as a head unit for another PM and combining the data could be really cool.

Im curious, have you used an ibike?

Im curious, have you used an ibike?

I have not but I know several people who have, including one person who's research was used to develop the sensors used in it. My statement was that it is not as accurate as a torque based PM. I specifically said that it could still be useful. Are you refuting that? Do you honestly think that infering power is as accurate as measuring it directly?

PM curveship. He has done quite detailed testing on his iBike and I'm sure would be happy to pass along the results.

Paging Curveship!

Please post your results here! I'm curious what they have to say.

I have used it(gen II). I have also owned a PT, PTSL and Quarq. The ibike did quite well if I were solo training on nice roads and were trying to hold the power, i.e. 2x20's. But once I moved from hoods to drops, sat up to climb or started group rides, it was quite a ways off. Now I did only borrow it for a week, but that is all I needed to make me want a "true" power measuring device.

I have not but I know several people who have, including one person who's research was used to develop the sensors used in it. My statement was that it is not as accurate as a torque based PM. I specifically said that it could still be useful. Are you refuting that? Do you honestly think that infering power is as accurate as measuring it directly?

Just asked if you had used one. Its already useful by the way. So many people that have not used one with input. Since there are many reports of accuracy when compared side by side it seems like it is just as useful as any others.

Just asked if you had used one. Its already useful by the way. So many people that have not used one with input. Since there are many reports of accuracy when compared side by side it seems like it is just as useful as any others.

From all accounts it is accurate as long as the dynamic factors match the static calibrations as closely as possible. As soon as those change, i.e. different road surface, different position, etc. then the accuracy decreases. Torque PMs aren't perfect either as their strain gauges depend on temperture which can drift throughout a ride. Also, as many of you probably know, I had issues with my first Quarq so it is important to check the calibration of any device.

Although they keep getting closer, the Ibike is clearly not as accurate as a good "real" direct measuring power meter. The question is, is it accurate enough? That'll depend on what you use a PM for. For example, I don't look at my 5sec power numbers much, other than to dispair at how pathetic they are. For my purposes- 5 to 20 min intervals, entire climbs, and tracking TSS, it might be just fine. For someone who wanted to see the difference between different aero setups, no way (unless you pair it with a direct meter, then it'd be awesome).

All you really need to know is the guy who does their tech support and boards and is part of the R&D team uses something other than an iBike for his own training.

I'm really waiting to find a PT wheel built for $550. or a hub for 450

Although they keep getting closer, the Ibike is clearly not as accurate as a good "real" direct measuring power meter. The question is, is it accurate enough? That'll depend on what you use a PM for. For example, I don't look at my 5sec power numbers much, other than to dispair at how pathetic they are. For my purposes- 5 to 20 min intervals, entire climbs, and tracking TSS, it might be just fine. For someone who wanted to see the difference between different aero setups, no way (unless you pair it with a direct meter, then it'd be awesome).

See the Ibike aero. This is what it's meant for.

I just read this doc, which shows some reasonable accuracy. Seems the gen III has worked out some of the problems. Anyone using the gen III for a while now have any regrets?

http://www.ibikesports.com/documents/Johnson_ride_analysis.pdf

I too would be interested in hearing from people with experience with the third generation device. Pcad, your opinion has been made abundantly clear :)