I just bought a Fluid2 and have a Garmin Forerunner 405, what else do I need to buy to be able to monitor my data on the trainer? I see Garmin sells a bike speed/cadence sensor, is this any good? What other options are there?
The garmin speed and cadence sensor works great. It’s pretty much all you need to keep track of distance, current speed and cadence. If you don’t have a power meter, this is about the best you can do. I feel though that the data that you get from it is a little skewed and usually on the lower side compared to how it would be outside. But it gives you something to go off of besides heart rate only.
I just bought a Fluid2 and have a Garmin Forerunner 405, what else do I need to buy to be able to monitor my data on the trainer? I see Garmin sells a bike speed/cadence sensor, is this any good? What other options are there?
Any rear-wheel speed/cadence sensor + bike computer will work to display your speed, which is analogous to power.
See here for the speed to power conversion curve:
http://thebikegeek.blogspot.com/2009/12/while-we-wait-for-better-and-better.html
Another option which is brand new but seems cool (albeit with a monthly fee) is the Trainerroad.com website. You would need to purchase a $30ish ANT+USB stick for your computer but then the Garmin speed/cadence sensor (which is ANT+) will transmit data to your computer, and it’ll display your power and other goodies on your computer screen like a Computrainer. Neat stuff.
In addition to the options mentioned above:
I haven’t used it, but Golden Cheetah supports “virtual power” in realtime mode using ANT+.
If you don’t want to run a computer with the trainer you can use SportTracks plus a plug-in to estimate power for post-ride analysis.
All of the options mentioned lack “calibration” so results for power estimation may vary. You will at least be able to track heart rate, distance and cadence.
Long time lurker first time poster.
Would it be possible to just read the speed data that the cadence/speed sensor is sending to the watch with the ANT+ USB stick that came with the watch?
If that is possible, then we can just plug the speed into that cubic equation on http://thebikegeek.blogspot.com/...tter-and-better.html and display it on the computer screen - instant and free power meter!
It would be awesome if someone with ANT+ expertise can chime in.
I have ANT expertise and I built something for you real quick: www.TrainerRoad.com 
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We find the power calculations to be pretty consistent if you tighten your trainer wheel down the same and keep your tire at the same pressure. The power curve offset moves a bit once the trainer warms up, but once you get going it’s pretty consistent.
This is all dependent on the type of trainer you have though. I’ve been testing with the Kurt Kinetic Road Machine which is known to have a power curve that’s not effected by heat.
I just bought a Fluid2 and have a Garmin Forerunner 405, what else do I need to buy to be able to monitor my data on the trainer? I see Garmin sells a bike speed/cadence sensor, is this any good? What other options are there?
Any rear-wheel speed/cadence sensor + bike computer will work to display your speed, which is analogous to power.
See here for the speed to power conversion curve:
http://thebikegeek.blogspot.com/...tter-and-better.html
Another option which is brand new but seems cool (albeit with a monthly fee) is the Trainerroad.com website. You would need to purchase a $30ish ANT+USB stick for your computer but then the Garmin speed/cadence sensor (which is ANT+) will transmit data to your computer, and it’ll display your power and other goodies on your computer screen like a Computrainer. Neat stuff.
Ummm…not really.
My experience with running a Fluid2 trainer in conjunction with a REAL power meter is that the load tends to vary significantly when the fluid heats up at certain power levels (IIRC, it was at ~250W and above).
Combine that with the uncertainty due to tire choice, pressure, roller force, etc…I wouldn’t put too much stock in having anything remotely “accurate” about a power guesstimate based on speed alone.
Sorry to throw a wet blanket over the idea…
Buy at PowerTap hub.
I just bought a Fluid2 and have a Garmin Forerunner 405, what else do I need to buy to be able to monitor my data on the trainer? I see Garmin sells a bike speed/cadence sensor, is this any good? What other options are there?
Any rear-wheel speed/cadence sensor + bike computer will work to display your speed, which is analogous to power.
See here for the speed to power conversion curve:
http://thebikegeek.blogspot.com/...tter-and-better.html
Another option which is brand new but seems cool (albeit with a monthly fee) is the Trainerroad.com website. You would need to purchase a $30ish ANT+USB stick for your computer but then the Garmin speed/cadence sensor (which is ANT+) will transmit data to your computer, and it’ll display your power and other goodies on your computer screen like a Computrainer. Neat stuff.
Ummm…not really.
My experience with running a Fluid2 trainer in conjunction with a REAL power meter is that the load tends to vary significantly when the fluid heats up at certain power levels (IIRC, it was at ~250W and above).
Combine that with the uncertainty due to tire choice, pressure, roller force, etc…I wouldn’t put too much stock in having anything remotely “accurate” about a power guesstimate based on speed alone.
Sorry to throw a wet blanket over the idea…
And quite a number of folks have had the exact opposite findings, finding that it’s spot on dead-on accurate, with Powertaps. Even KK trusts theirs enough to place a speed-power converting head onto their KK.
My Fluid2 is dead-on reproducible. In a single week workout, when I’m targeting exact speed/power levels, my HR values are spot-on reproducible every time. I do check tire pressure, and make sure I lock it on the trainer similarly, but it’s not hard at all. It has been extremely good for power-based training. And I can definitely notice the difference between 22 and 21mph quite readily (even more apparent at 23 to 22mph for me) so if there is any drift, it’s way under 0.5mph, which outstanding precision.
Taking indoor numbers to outdoor numbers has its own challenges - I’ll agree that you still should test outdoors to get the best outdoor numbers as conditions between both are different.
I do think it’s exaggerating to say the Fluid2 power curve is not reproducible - there have been people who have posted their PT curves on from KK or Fluid2 and they’ve been dead-on.
To add what lightheir wrote, I’ve been testing the KK road machine power curve with a power tap and had my numbers line up really close. If I tighten down the wheel the same and have the same pressure I can use a consistent offset and get the avg watts for my intervals with 0-5 watts.
I have a fluid2 sitting in my garage waiting to be tested. I’ll be blogging about those results once i’ve done a few rides.
Does anyone have any experience with consistency of the TacX trainers using speed as proxy for power (i.e. Satori or Booster)?
I just bought a Fluid2 and have a Garmin Forerunner 405, what else do I need to buy to be able to monitor my data on the trainer? I see Garmin sells a bike speed/cadence sensor, is this any good? What other options are there?
Any rear-wheel speed/cadence sensor + bike computer will work to display your speed, which is analogous to power.
See here for the speed to power conversion curve:
http://thebikegeek.blogspot.com/...tter-and-better.html
Another option which is brand new but seems cool (albeit with a monthly fee) is the Trainerroad.com website. You would need to purchase a $30ish ANT+USB stick for your computer but then the Garmin speed/cadence sensor (which is ANT+) will transmit data to your computer, and it’ll display your power and other goodies on your computer screen like a Computrainer. Neat stuff.
Ummm…not really.
My experience with running a Fluid2 trainer in conjunction with a REAL power meter is that the load tends to vary significantly when the fluid heats up at certain power levels (IIRC, it was at ~250W and above).
Combine that with the uncertainty due to tire choice, pressure, roller force, etc…I wouldn’t put too much stock in having anything remotely “accurate” about a power guesstimate based on speed alone.
Sorry to throw a wet blanket over the idea…
And quite a number of folks have had the exact opposite findings, finding that it’s spot on dead-on accurate, with Powertaps. Even KK trusts theirs enough to place a speed-power converting head onto their KK.
Well…quite a few number of folks have shared the exactly what I’m talking about right here on ST. Here was a thread just last year:
http://forum.slowtwitch.com/gforum.cgi?post=3039889;search_string=fluid2;#3039889
As far the KK goes, I don’t know…but, we’re talking about the Fluid2 here…
My Fluid2 is dead-on reproducible. In a single week workout, when I’m targeting exact speed/power levels, my HR values are spot-on reproducible every time. I do check tire pressure, and make sure I lock it on the trainer similarly, but it’s not hard at all. It has been extremely good for power-based training. And I can definitely notice the difference between 22 and 21mph quite readily (even more apparent at 23 to 22mph for me) so if there is any drift, it’s way under 0.5mph, which outstanding precision.
So…what you’re saying is that you haven’t actually checked it against a power meter. Got it.
I do think it’s exaggerating to say the Fluid2 power curve is not reproducible - there have been people who have posted their PT curves on from KK or Fluid2 and they’ve been dead-on.
Well…I’d question as to how exactly those power curves were generated. Here’s a big reason why…check out the plot below. It’s from a workout I did last January that I call the “Shortened Hour of Power” where the plan was to gradually increase the power every 3 minutes while throwing in a 15s “sprint” at the end of each 3 min. interval. I did the whole thing in a single gear. Take a look at the third interval where I started pedaling a bit more “evenly”. The average power was 192W at 93rpm. As you can see, the average cadence (the green plot) stays basically constant throughout the 35 minute session, while the power (the yellow plot) gradually creeps up. In the last interval, which had the EXACT same average cadence (and thus same rear wheel speed) as the 3rd interval, the power was up to 223W for the interval. Thats a 29W difference!
This is interesting. Is cadence being measured with a sensor independent of the powertap in your trial?
Edit: i ask in reference to this post: anonymous.coward.free.fr/wattage/rosetta/rosetta_details.html, which refers to powertap cadence holes near your target cadence.
This is interesting. Is cadence being measured with a sensor independent of the powertap in your trial?
Edit: i ask in reference to this post: anonymous.coward.free.fr/wattage/rosetta/rosetta_details.html, which refers to powertap cadence holes near your target cadence.
That plot is from a CinQo/Garmin 705 combo. Cadence from the CinQo.
Oh…and here’s the plot of the constant cadence cassette “sweep” I was referring to in the post I linked to above. This is after warming up the trainer for 16 minutes. Compare the cadence and speed curves ( I used a Garmin speed/cadence sensor in this run) to the power for laps 4, 8, and 10…not too stable, huh?
edit: BTW, my intent with this run was to try to create a power curve for the Fluid2…actually, I was going to plot P/V vs. V^2 to get the “virtual CdA and Crr” (like I eventually did with the LeMond Revolution http://forum.slowtwitch.com/...rtual%20cda;#3178482 )…but, after seeing the above, I realized the effort was somewhat futile.
Good data, thanks. I suspect you’re right about the fluid warmup, but I still don’t think the variance is enough to make the Fluid2 not a good candidate for power-based training.
One critique for your data - you are using CADENCE vs POWER, which is not entirely the same as using speed. In fact, your graphs themselves show a much tighter correlation with SPEED vs POWER. I don’t know why the speed/cadence is uncoupling, but your data is clearly showing it, whereas the speed - power correlation is much tighter.
I could theorize about why this might be, and it would just be guessing as to why the cadence/speed are uncoupling, but your data points are clearly showing both uncoupling of cadence vs speed as well as a much tighter correlation of speed vs power, to the point that I’d be very happy using it speed as the power correlate.
If you’ve got data with a flat speed profile and power, that would be helpful as well.
Either way, its still WAY better than HR.
Good data, thanks. I suspect you’re right about the fluid warmup, but I still don’t think the variance is enough to make the Fluid2 not a good candidate for power-based training.
Really? You don’t think a variance of 29W over ~30 minutes at a constant cadence (and wheelspeed since it’s all in one gear) isn’t “enough”? Really??
One critique for your data - you are using CADENCE vs POWER, which is not entirely the same as using speed.
Ummm…when in a single gear, cadence is directly proportional to speed…unless my chain is slipping, or something :-/
In fact, your graphs themselves show a much tighter correlation with SPEED vs POWER. I don’t know why the speed/cadence is uncoupling, but your data is clearly showing it, whereas the speed - power correlation is much tighter.
I think you might be getting fooled by the fact that cadence is reported in integer values (and therefore the plot looks more “chunky”) as opposed to the finer resolution on the speed. However, if you really think that the speed power correlation is “tighter”, I’m having a hard time seeing how you’re getting that. I’ll look into the individual correlations later if that will appease you…
I could theorize about why this might be, and it would just be guessing as to why the cadence/speed are uncoupling, but your data points are clearly showing both uncoupling of cadence vs speed as well as a much tighter correlation of speed vs power, to the point that I’d be very happy using it speed as the power correlate.
I’m thinking your confirmation bias might be showing here…
If you’ve got data with a flat speed profile and power, that would be helpful as well.
It’s right there in front of you with the first plot (cadence is proportional to speed)…also, the individual intervals in the second plot are at nearly constant cadence/speed as well…
Either way, its still WAY better than HR.
In this case, I don’t agree…
TomA - you’re ignoring your very own data and just going on a presupposition.
I’ll make it clear:
Compare the distance between the SPEED (blue) curve and the POWER curve in the 2nd graph. (You conveniently left out the blue curve in your first graph just to make your point about cadence.) The speed and power curves stay nearly the same distance apart during all intervals.
I admitted that I can’t explain why your cadence doesn’t couple with the power - I would expect it to, but as we’re debating the merits of SPEED, you must look at the speed data and not ‘infer’ from your cadence data, which doesn’t correlate well with either speed or power on your 2nd graph.
You can’t cherry pick your data points. You might still be right, but at least with what you’ve posted, the data is supportive of good consistency for speed-power relations. If you reshow the 1st graph and include the blue speed curve overlaid on your power data, it may also further support speed-power.
I never use cadence as a surrogate for power, ever, and I don’t know anyone who does as well.
Compare the distance between the SPEED (blue) curve and the POWER curve in the 2nd graph.
Are you referring to the green curve?