Gen III

[TNT]

I am in the process of deciding on a powermeter. PT, SRM, and IBIKE are all on the table. Do you have any comparison of these with the new Gen III IBIKE

Thanks

[coachboyd]

I have been beta testing the Gen3 for a little while. Here is a ride I did with the Quarq Cinqo (similar to SRM) and the iAero on the bike at the same time.

A couple of things to note about this file:
This was done with a beta firmware. That is the biggest thing we have been working on in the past couple weeks is getting the firmware ready for release. There has been a couple improvements added since I did this ride to make the results even better.

This is VERY typical of what I am seeing on a daily basis. In fact, I did a ride with an iAero, Quarq, and a Power Tap (the link to it is on my homepage in my profile). With the iBike software, you can do a file comparison of the power meters. We were doing tests at Interbike where we asked people to try and guess which file was which. Nobody could come up with a definite answer.

So, the question is. . .why pay 3000 dollars when you can pay less than 800?
I have been racing all year on a domestic racing scene and have been so impressed with the way my Ibike worked that I sold my other power meters on eBay.

[TNT]

Boyd,

First thanks for the quick response. My biggest concern is on the bike accuracy. I plan on using it for training and racing. So to use it for what I want to I just need to be sure the power measurements on the bike are accurate real time, not post ride.

I currently train with a PT (the old heavy yellow hub) and others on my team have the SRM, various PT's, and one has the new Quarq (Garmin). Of all, the Ibike interest me the most for the value,no special wheels or cranks, and no weight penalty. Plus all the extra info, wind,slope.....


Thanks

[coachboyd]

The tilt correction algorithm from the iBike 2 software was built into the computer head for Gen3. This means the numbers you are seeing on the computer are the same as after you analyze the file in the software. There have also been added accuracy to the wind offset. What this all means is the numbers you see on the computer are the numbers that you are really putting out.

I have done a lot of riding with Gen2 paired up to my Quarq, and Gen 3 reading by itself. I have found it amazing that at almost all times both units were so close to each other that I actually stopped a couple times to make sure that Gen3 wasn't actually paired up to the Quarq as well.

Take the uploaded image from a recent ride I did. You can see the green line stay nice and flat for most of the ride. When I did a long bumpy downhill (in an aero tuck and actually changed the riding tilt) the green line starts to move a little upward, but you can see it correct itself right away and stay flat for the rest of the ride.

[Brodirt]

Do you have any idea when Gen III will be shipping?

[coachboyd]

November 1st

[rruff]

The tilt correction algorithm from the iBike 2 software was built into the computer head for Gen3. This means the numbers you are seeing on the computer are the same as after you analyze the file in the software. There have also been added accuracy to the wind offset. What this all means is the numbers you see on the computer are the numbers that you are really putting out.

Is a pre-ride tilt cal still necessary or desirable? Do you know how often the firmware samples the elevation change and compares it to the tilt-derived value? In other words how often does it apply the correction?

I did a little experiment where I did a wind offset at room temperature (72deg), then heated up my iBike to 102 deg (hairdryer) and cooled it down to 50 (freezer) then let it slowly warm up in the room again, to see how much the offset changed. These are the results:

Temperature, Offset (N/m^2)

72,0
102, 7.3
95, 5.7
88, 4.1
78, .6
66, -3.8
50, -9.5
58, -4.1
65, -1.0
68, 0
69, .4

I didn't allow the temperature to fully stabalize at each reading, but it still gives a rough idea of how temperture effects the wind offset. Could you do something similar for the new unit? I'm trying to figure out how much better the new unit will be.

[rruff]

I have been racing all year on a domestic racing scene and have been so impressed with the way my Ibike worked that I sold my other power meters on eBay.

The question that always comes up is iBike's tendency to underreport power when drafting. Since you have done a lot of racing with multiple units, can you tell us what the magnitude of this error is in different circumstances?

[coachboyd]

I don't know how much I am allowed to divulge, but there has been a wind offset calibration done along all temperatures in the factory. This means if you start off at 40 degrees and it warms up to 80 degrees, your wind offset should change by less than 1.0. Changing wind offsets should no longer be a problem.

As for your second question, I just wrote a big post in here
http://www.ibikeforum.com/viewtopic.php?f=4&t=521

You can check that out. The biggest place that inaccuracies could happen is the power spikes that you see in a criterium. Because when you jump out of the corners, your CDA actually changes and for the brief second or two that you are putting out 600+ plus, the iBike can under-report that. So, when you look at a power comparison for a criterium, the highest spikes should be a bit higher on the DFPM. I have come up with a fix for this and we will be implementing it later in a firmware upgrade, but we didn't want to delay getting the new units out. And for something that causes watts to be off for a small period of time, and only in criterium situations, it was one of those things that could wait a couple months (I don't think anybody is doing crits in November anyway).

You can be sure that if I am going to use this for my training and racing, it is going to be something that is very dependable and accurate. I take power training very seriously, both in my racing and my coaching. I'd like to think that's what has allowed me to excel in both those fields.

[rruff]

I don't know how much I am allowed to divulge, but there has been a wind offset calibration done along all temperatures in the factory. This means if you start off at 40 degrees and it warms up to 80 degrees, your wind offset should change by less than 1.0. Changing wind offsets should no longer be a problem.

Great! That is a big improvement.

Now one more question... they've said that the new unit will use less power. I have a wired unit, so it has the biggest issues with battery consumption in cold weather. I was planning to get the kit so I could hook up an external battery. Is this something that would be necessary with Gen III? Is the difference in power consumption big or small? I will do a fair amount of winter riding in 40 degree temps, but no colder.

[jim_s]

rruff - what's this external battery kit you refer to?

Jim

[coachboyd]

rruff - what's this external battery kit you refer to?

Jim

The wireless mount has a battery in it. When you use the wireless mount with the iBike, battery life is greatly increased. . .especially in cold weather situations.

[jim_s]

Ah, ok - Thanks.

I thought he'd found some kit to allow hooking up an ext batt to a wired mount.

[rruff]

rruff - what's this external battery kit you refer to?

Jim

Velocomp was offering a wired mount "kit" (basically just an open case with some extra wires attached) that allowed you to hook up an external battery. I haven't used the iBike in the winter yet, but apparently the 2032 batteries can't power the unit for more than a few hours when it is cold.

[jim_s]

Yes, I've seen those referenced in long-dead posts - are they still available? I've been working on one or two hacks that would allow me to get power from an external battery to my wired (cadence) mount, but if there was a mount that I could attach wires to internally, that'd seriously simplify things! Does anyone know if these mount kits are still available?

Also, on the subject, I recall (perhaps on the old Topica board) seeing a picture and/or a wiring diagram that indicated which pins on the mount could be used for power. Can someone direct me to those diagrams and/or tell me which pins do what? Also related to the subject of wiring - is adding cadence to a wired mount a simple matter of wiring in a cadence sensor (such from another computer mount), or is there electronics in the mount associated w/ that? (I ask, because I have an older wired non-cadence mount that I'd hook up to use w/ my trainer if I could, vs routing my primary mount speed pickup down to the rear wheel w/ an extension.)

[rruff]

Here is the link (just sent to me by Travis) to wiring an external battery to the pins: http://lists.topica.com/lists/iBikeProP ... start=1742

Says he used 2 AAA batteries... which I guess is nominally 3V if alkalines wired in series. NiMH batteries wouldn't work though, since they are only 1.2V ea.

I think Velocomp will sell you a kit too which includes the mount... would be cleaner but more expensive.

[jim_s]

Thanks rruf - that's exactly the picture I'd previously seen!

The question still stands as to whether or not anyone knows if its possible to just hook a cadence magnet up to two posts on the wired mount, or it there's more to it than that.

[racerfern]

I remember that post from the topica list. In that post there is reference to someone using a Duracell Type CR123A Photo Battery instead of two AAs. The CR123A is 3v and capable of hundreds of flashes in a modern camera. The posting I remember placed the battery in the handlebar end with wires up to the unit.

[rruff]

I wonder which works better in the cold... since the Lithium batteries obviously aren't great or we wouldn't have this issue in the first place.

Ok... a little googling found this on a photo forum: "At -4 degrees F both NIMH AA and Lithium CR5 batteries are down to 1/2 normal capacities. At 32 degrees F both are down to between 90% - 95% of capacity. Alkaline AA cells are down to 65% at 32 degrees F and useless at -4 F."

So it looks like Lithium would be the best in the cold... plus you only need one of them.

I think I'll tape the battery inside the stem... make a little groove under the faceplate to thread the wires through.

BTW according to Travis the power consumption of the new iBikes should be about the same as the old ones, so an external battery will be a good idea for the wired units in the winter.

[jim_s]

I use two CR123A's in series in small radio-control gliders and the suckers last forever - I usually get ~20 hours of flying time from them, though that's from a pair. That's easliy 4-5x as long as I get from rechargeable nimh and nicd packs consisting of 4 batteries though. I don't generally use them in real cold temps though, so can't say how they hold up comparatively, but capacity wise, they should completely blow way the button batts.

I tried gently prying the top off of my old wired non-cadence mount last night, but met w/ too much resistance and in an uncharacteristic bout of self control, I quit before I did any damage to the mount. It seems pretty firmly glued together though.

I'm going to work on a batt adapter this weekend - colder temps are on the way and I'd rather not chew through a few dozen buttons this winter.

[rruff]

I tried gently prying the top off of my old wired non-cadence mount last night, but met w/ too much resistance and in an uncharacteristic bout of self control, I quit before I did any damage to the mount. It seems pretty firmly glued together though.

Me too... I think they are glued together quite well now.

I'm going to work on a batt adapter this weekend - colder temps are on the way and I'd rather not chew through a few dozen buttons this winter.

Don't know if you used yours last winter, but I've heard that a new battery might not even make it through *1* ride. I guess it isn't so much a capacity problem as a voltage problem. The battery could supply juice at say 2.5V at cold temps, but this is too low for the iBike to work properly. So... back tracking... if the new iBike is capable of tolerating lower voltages, then it wouldn't matter if its power draw was the same... it would work ok in the cold.

[cghebert]

I have a CR123A battery wired up to my mount and it has lasted over a year (though an injury limited my riding this summer) and is definitely better in the cold weather. I ran the wire underneath my handlebar tape and the battery sits in the end of my handlebar. A while back, the iBike folks obliged all of us who were making our own custom mounts by selling a kit that included an unglued mount and instructions for wiring up an additional battery. If people are interested, I can dig up the instructions.

[jim_s]

I am very interested!!

Thanks!

[cghebert]

I am very interested!!

Thanks!

Jim,

Sorry for the delay on this, but here are the supplementary instructions iBike sent out with their iMount kit a while ago. You might be able to convince them to send you another kit, but if not I guess you can try and pry open one you have now. It can be tough to open up, but as long as you don't mangle it too badly, you should be alright. Their instructions are fairly straightforward, the only thing I would add is that when reassembling the mount, the connection between the iBike and mount doesn't get secure enough to make electrical contact until the mount is securely glued. Meaning, you can't really test your connections until you glue the mount, so make sure the wiring is correct the first time. Good luck and let me know if you have any questions.

[Velocomp]

We still have some iMounts for sale; $40.

[Norm]

We still have some iMounts for sale; $40.

John, have you considered offering a battery collar that would sit between the iBike and the mount? I envision this to be a mount extension or riser which would contain additional batteries and pass the leads from the mount to the iBike. Riders could put it on whenever the weather is cold and leave it home when the weather is warm.

[jim_s]

Thanks for posting that cghebert - I appreciate it!!

I like the idea of that little donut that would sit between the ibike and the mount - it could twist onto the mount, then the iBike could twist onto it. (Wonder if the height diff would be enough to throw off the coast-down?)

I'm afraid that we wired holdouts are a bit of a group of dinosaurs though - VC seems to be pushing wireless pretty heavily, so I'm not sure it'd warrant them putting much time, effort or $$ into developing such an item for a bunch of retro-grouches.

[alback]

The problem with an additional collar, battery or otherwise, is it introduces additional play between the iBike and the mount. The bonding of the ibike through the mount to the bike is important. Some have taken to literally epoxy the mount to their stem.

Additional play in the mount with a collar reduces the effectiveness of the IBike's calculations. If you want to add battery power by means of an additional module, incorporate it on the other side of the stem. Not between the ibike and the mount. Actually a larger module below the mount will also serve to improve the mounts surface area at the stem and stabilize the mount more than todays small band design.


Alan

[jim_s]

alback - good point about the play - it'd have to be a tight fit, though I'd trust the folks at VC to do a good job on that! I think the main consideration in pondering putting something between the mount and the computer is just the ease of injecting power into the system w/o having to rip apart the (very well-glued-together!) mount.

It looks like the best idea going thus far, aside from the iMount (which at $40 is enough to make one try to be a bit inventive), is the thin brass strips that overlap the lip of the mount - it gets something between the items, but doesn't affect the solidity of the mount (and if anything, would probably serve to further tighten the fit, in fact!

[jim_s]

BTW, has anyone gotten a Gen III or notice of a Gen III shipping yet?