Why bother if you have 4 PMs already ?

May as well give give the money to a worthy cause

The market has moved on in terms of value since ibike last brought out something.

Plenty of better, credible solutions around now...

Well I have a Triathlon bike (Quarq Elsa), a general road bike (Quarq Riken), a general winter bike (currently using a powertap) and a road race bike (SRM). I also lend out the powertap occasionally to people thinking of investing in a power meter so they can see what it is all about before they buy one. I know you could do it all with 1 power meter, but I like to set the bike up and then leave it - otherwise I spend hours and hours just getting bikes ready to ride. My wife has bikes that she needs me to maintain and I ride a motorbike for commuting so time is a major factor for me.

I would like to try out the iBike thing and potentially use it on my mountain bike as I don't have any plans to put power on there, but am always guessing at my TSS scores for those rides. My mountain bike is one I built on the cheap from a frame so has a big mixture of old second hand parts that don't really gel well together. Putting an expensive power meter on there just to record TSS makes no sense, but the iBike thing could be an easy way to get something better than an estimate. Also useful when one of the others is out of action. For instance the Riken started life as a S975 but had to go back twice due to reed switch issues and came back with a replaced riken spider the second time - the SRM goes off once a year for calibration and new battery. Could be an easy replacement albeit not as accurate while the other one is away.

Dealing with bottom bracket issues these days is no fun either :-(

Not big issues but for £300 why not???

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He who understands the WHY, will understand the HOW.

Seems like the perfect application of the powertap powercal. $100 is cheaper than the $300 and will give a better idea of pacing than a normal heart rate monitor and probably better than this ibike.

If its even close to being accurate it will be good enough to get decent TSS for rides where I am using a bike without a regular power meter on there.

I decided that just using Strava-watts for road riding was far easier and good enough for that purpose. Nice having the GPS route also. I just keep a little GPS in my pocket now.

I would like to try out the iBike thing and potentially use it on my mountain bike as I don't have any plans to put power on there, but am always guessing at my TSS scores for those rides.

It will probably be very poor in that application. Rolling resistance on many (most?) MTB courses is more important than wind. With the iBike Crr is an assumed constant.

I think Strava-watts would be about as accurate with a little scaling.

I used my iBike with Powertap for VE back around 2007-2008. The problem is that the iBike data is so coarse that it really doesn't get you very much. It didn't really help me narrow down CdA/Crr pairs; about all it helped for was clearly indicating when a run should be thrown out due to wind.

How did you use the airspeed data, exactly? I was thinking it might be useful if wind is fairly high and fluctuating.

Maybe you are right about it being useless. Most of us care about this for TT bikes which perform well in crosswinds. I eventually came to the conclusion that a simple wind vector relative to forward motion was adequate because CdA is lower at high yaw, and tends to cancel the effect of crosswinds increasing the total wind (headwind) in both directions. In other words I assume a 90 degree crosswind is the same as no wind at all. In reality the crosswind will create a higher forward airspeed, but the CdA will be lower.

The iBike will however register a headwind when you have a crosswind, so you can't just make the wind average to zero on your VE runs.

And IME for anyone who is interested, the iBike data (at least up to gen 3) needed to be tweaked quite a bit in software after the fact. The airspeed calibration was not a set and forget kind of thing.

With no wind speed output and no way to log it, this will be useless for CdA estimation.

I've found that crosswinds don't have as much effect as some would have us believe. Taking a headwind measurement (which has some angular tolerance) is sufficient to cope with normal testing conditions. I haven't gone out of my way to see what happens when it's really windy though

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Developing aero, fit and other fun stuff at Red is Faster

I've found that crosswinds don't have as much effect as some would have us believe.

What do you mean exactly?

The magnitude is not great. The last 2 runs I've done don't have much happening past 5°. This doesn't affect the measurement much (depending on mechanical design)

My test riders are not 'slow' guys on the Kona course it has to be said.

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Developing aero, fit and other fun stuff at Red is Faster

Can we have a show of hands of those who have actually used the new technology (The Newton) versus earlier iterations. Mine is very consistent comparing ride to ride over the route/conditions. My power numbers match up well relative to ftp as tested on the computrainer.

Isn't that the default state to be in?

I have compared starve watts before. They can be close, or they can be a country mile out. I am sure the iBike would give better and more consistent results.

I had not thought of the powercal before - not a product I thought could give anything like representative results, but will check out the DC review and give it some thought.

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He who understands the WHY, will understand the HOW.

I made no assertions about the accuracy of ibike products. I have not used one.

From the data I have collected though I can see why estimating power in this way is fraught with difficulty. This is why I have suggested that having the ability to record airspeed, atmospheric and direct power data together will be more useful.

Aero "rule of thumb" at 48km/h is:
50g of drag = 5 w = 0.5 s/km = 0.005 m^2 CdA = 0.0005 Crr

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Developing aero, fit and other fun stuff at Red is Faster

Many of the posts in this thread make comments re early iterations of ibike products. The Newton is a very cool device. It provides elevation profiles, grade percentage measurements during the ride, speed, heart rate, power (using advanced algorithms that match well against strain gauge technology), elapsed time, cadence, and much more beyond power. Some comments said it is difficult to set up and/or use. The present Newton setup and use are pretty simple. I have found the support to be better than average over the 3+ years I have had mine. Updates to firmware and the computer software have been regular. I think it is a good value for the price.

Nothing I have stated is incorrect.

Most ant+ head units receive power, speed, cadence
No ant+ units receive airspeed.

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Developing aero, fit and other fun stuff at Red is Faster

Would not work in a mountain bike application. At best it could be used as a power random number generator. But if looking for random numbers just use Excel or Matlab.

So if I ride the trainer with a HUGE fan, will I produce more watts with this?

I've had the Newton for the last couple years. I assume this is just a simplified version of that. It's the only power meter I've ever used. Honestly it's pretty much worthless indoors. It just uses the power curve from your trainer and then uses your speed to estimate your power. Outdoors I've been very happy with it. Set up can be a bit confusing but like it was stated earlier their customer support is very helpful and easy to get in touch with. I've got nothing to compare it with but for what I payed for it I believe it gives me a pretty accurate power readings. When ride is done and uploaded to my computer it gives me all the information I would need. I've got a cyclops powerbeam so when I ride indoors I just use that. Comparing efforts indoors and outdoors my power readings seem to be in the range I would expect them to be. Biggest complaint about the unit is not the most user friendly.

Have decided to get a powercal for the off season mountain bike riding and see what sort of results I get with it. What is the worst that can happen ??

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He who understands the WHY, will understand the HOW.

i've been on the fence about a PM mainly because even though i do the exact same route (only 1 paved road here and you can go north or south on it) the conditions vary so much I'm not sure a PM would be helpful. we have head, cross and tailwinds. we have heat and humidity. for example, i did a ride on Tuesday wtih same time in Z3 and same avg HR that Thursday was 4.5 min slower with same avg HR and z3 time as Tuesday's ride. Thursday felt like a much harder effort (Tuesday felt like tailwind coming and going). Could the powercal address that if you know?

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