Quantcast
    MAIN INDEX RULES & LEGEND LOG IN  

Slowtwitch Forums: Triathlon Forum:
What are my options for monitoring data on Fluid2 trainer?

 

First page Previous page 1 2 Next page Last page  View All  


trigu

Oct 17, 11 13:02

Post #1 of 32 (3648 views)
What are my options for monitoring data on Fluid2 trainer? Quote | Reply

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?


elevario

Oct 17, 11 13:10

Post #2 of 32 (3643 views)
Re: What are my options for monitoring data on Fluid2 trainer? [trigu] [In reply to] Quote | Reply

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.


lightheir

Oct 17, 11 13:13

Post #3 of 32 (3637 views)
Re: What are my options for monitoring data on Fluid2 trainer? [trigu] [In reply to] Quote | Reply

trigu wrote:
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.


SummitAK

Oct 17, 11 15:56

Post #4 of 32 (3596 views)
Re: What are my options for monitoring data on Fluid2 trainer? [trigu] [In reply to] Quote | Reply

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.


seifufu

Oct 17, 11 16:51

Post #5 of 32 (3566 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

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.


(This post was edited by seifufu on Oct 17, 11 16:53)


Nate Pearson

Oct 17, 11 19:51

Post #6 of 32 (3523 views)
Re: What are my options for monitoring data on Fluid2 trainer? [seifufu] [In reply to] Quote | Reply

I have ANT expertise and I built something for you real quick: www.TrainerRoad.com :)
---------------------------------------------------------
http://www.trainerroad.com - Indoor Cycling Training System


Nate Pearson

Oct 17, 11 19:53

Post #7 of 32 (3521 views)
Re: What are my options for monitoring data on Fluid2 trainer? [SummitAK] [In reply to] Quote | Reply

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.
---------------------------------------------------------
http://www.trainerroad.com - Indoor Cycling Training System


Tom A.

Oct 17, 11 20:21

Post #8 of 32 (3511 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

lightheir wrote:
trigu wrote:
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...


http://bikeblather.blogspot.com/


howard11792

Oct 17, 11 20:52

Post #9 of 32 (3496 views)
Re: What are my options for monitoring data on Fluid2 trainer? [trigu] [In reply to] Quote | Reply

Buy at PowerTap hub.


Park City Condo Rentals
http://www.traverseridge.com


lightheir

Oct 18, 11 5:08

Post #10 of 32 (3450 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

Tom A. wrote:
lightheir wrote:
trigu wrote:
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.


Nate Pearson

Oct 18, 11 15:45

Post #11 of 32 (3359 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

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.
---------------------------------------------------------
http://www.trainerroad.com - Indoor Cycling Training System


bingobong

Oct 18, 11 20:32

Post #12 of 32 (3332 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Nate Pearson] [In reply to] Quote | Reply

Does anyone have any experience with consistency of the TacX trainers using speed as proxy for power (i.e. Satori or Booster)?


Tom A.

Oct 18, 11 20:36

Post #13 of 32 (3327 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

lightheir wrote:
Tom A. wrote:
lightheir wrote:
trigu wrote:
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/...ring=fluid2;#3039889

As far the KK goes, I don't know...but, we're talking about the Fluid2 here..


lightheir wrote:
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.

lightheir wrote:
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!



http://bikeblather.blogspot.com/


gardenvelo

Oct 18, 11 21:22

Post #14 of 32 (3313 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

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 post was edited by gardenvelo on Oct 18, 11 21:33)


Tom A.

Oct 18, 11 22:22

Post #15 of 32 (3301 views)
Re: What are my options for monitoring data on Fluid2 trainer? [gardenvelo] [In reply to] Quote | Reply

gardenvelo wrote:
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.


http://bikeblather.blogspot.com/


Tom A.

Oct 18, 11 22:34

Post #16 of 32 (3296 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

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.


http://bikeblather.blogspot.com/

(This post was edited by Tom A. on Oct 19, 11 6:49)


lightheir

Oct 19, 11 6:33

Post #17 of 32 (3261 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

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.


Tom A.

Oct 19, 11 7:51

Post #18 of 32 (3240 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

lightheir wrote:
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??



lightheir wrote:
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 :-/


lightheir wrote:
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...

lightheir wrote:
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...


lightheir wrote:
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...


lightheir wrote:
Either way, its still WAY better than HR.

In this case, I don't agree...


http://bikeblather.blogspot.com/


lightheir

Oct 19, 11 10:11

Post #19 of 32 (3222 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

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.


Tom A.

Oct 19, 11 10:38

Post #20 of 32 (3209 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

lightheir wrote:
Compare the distance between the SPEED (blue) curve and the POWER curve in the 2nd graph.

Are you referring to the green curve?


http://bikeblather.blogspot.com/


bhenn

Oct 19, 11 10:49

Post #21 of 32 (3202 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

Perhaps as the Fluid 2 "warms up" it provides more resistance at a given power output? Thus with the same gear and the same cadence you would produce an increased power output with increased duration?
__________________________________________________

"I'm gonna show you a hill that would choke a mule."


Nate Pearson

Oct 19, 11 11:19

Post #22 of 32 (3184 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

I'm surprised that the power load increased as you road. I'd think that the fluid would get thinner as you road and not take as much power to get through it.


We've seen big drops on some trainers/rollers. Even with the KK the wheel heating up changes the resistance. This usually flattens out after about 10 minutes though.


Tom, what do you think about a roll down test to account for this sort of drift on trainers that are affected by heat? We're trying to work that out now. ANT doesn't send us enough speed messages though so we are having to interpolate some of the values. I'm not convinced that we will be able to do it.

The idea would be that if you could do a quick roll down from 20 to 10 mph while you worked out that would take in account for the sort of drift you were seeing and adjust the offset for the power curve. On some trainers, you might have to do multiple roll down tests during your workout to correct for drift. Kind of a PITA but if you did it right it wouldn't be too intrusive.

---------------------------------------------------------
http://www.trainerroad.com - Indoor Cycling Training System


lightheir

Oct 19, 11 12:58

Post #23 of 32 (3147 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Tom A.] [In reply to] Quote | Reply

Tom A. wrote:
lightheir wrote:
Compare the distance between the SPEED (blue) curve and the POWER curve in the 2nd graph.

Are you referring to the green curve?

Nice try to play dumb.

As per the axes on your very own data:
Green - cadence
Yellow - power
Blue - speed

Blue and yellow curves correlate well. Nobody correlates cadence to power as you are doing.


Tom A.

Oct 19, 11 13:04

Post #24 of 32 (3142 views)
Re: What are my options for monitoring data on Fluid2 trainer? [Nate Pearson] [In reply to] Quote | Reply

Nate Pearson wrote:
I'm surprised that the power load increased as you road. I'd think that the fluid would get thinner as you road and not take as much power to get through it.

The behavior is consistent with what was reported about the "levels" in the thread I linked to above...i.e. increasing temps correlate to increasing load. Although one would expect things to get "easier" with higher temps (as the fluid viscosity drops), that would only be true in an "open" sytem. In a closed sytem like the Fluid2, my suspicion is that the increasing load is pressure related.


Nate Pearson wrote:
We've seen big drops on some trainers/rollers. Even with the KK the wheel heating up changes the resistance. This usually flattens out after about 10 minutes though.



Right...and in that case it's due to the rolling resistance of the particular tire decreasing as it heats up. In some Crr testing I've done on some 4.5" Kreitler rollers lately, I find that there's a bit of hysteresis in the power values based on what the tire speed was prior to the particular interval. In other words, it doesn't necessarly warm up to a constant temp...it's dependent on the wheel speed (and thus, on rollers, the power).


Nate Pearson wrote:
Tom, what do you think about a roll down test to account for this sort of drift on trainers that are affected by heat? We're trying to work that out now. ANT doesn't send us enough speed messages though so we are having to interpolate some of the values. I'm not convinced that we will be able to do it.


The idea would be that if you could do a quick roll down from 20 to 10 mph while you worked out that would take in account for the sort of drift you were seeing and adjust the offset for the power curve. On some trainers, you might have to do multiple roll down tests during your workout to correct for drift. Kind of a PITA but if you did it right it wouldn't be too intrusive.

That might work...you might want to try not having the speed sensor trigger off of the rear wheel, but glue a magnet to the roller drum and then mount the sensor there. That way you'll get more "triggers" per recording event...and presumably a more accurate speed calculation. I've done this for my roller Crr testing since I didn't want to have to compensate for tire diameter when testing various tires. You'll have to remember to enter the circumference of the drum instead of the tire for the rollout setting in your computer, though ;-)


http://bikeblather.blogspot.com/


Tom A.

Oct 19, 11 13:31

Post #25 of 32 (3126 views)
Re: What are my options for monitoring data on Fluid2 trainer? [lightheir] [In reply to] Quote | Reply

lightheir wrote:
Tom A. wrote:
lightheir wrote:

Compare the distance between the SPEED (blue) curve and the POWER curve in the 2nd graph.


Are you referring to the green curve?


Nice try to play dumb.



Not playing dumb, just trying to give you a chance to correct your mistake. I just thought that you were misreading the plot. After all, you stated that the speed and power curves kept a constant spacing between them within each interval. If you really think that the speed curve keeps a more consistent gap to the power curve than to the cadence curve in those intervals...well, then I don't know what to say. Especially if you look at Lap 4 and Lap 8.

Since you don't seem to be recognizing your mistake yet, I'll now address your previous statements:

lightheir wrote:
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.

Again...look at Lap 4 and Lap 8 (the higher power intervals) in particular, and make sure you're looking at the correct gap. BTW, I didn't "conviently" leave the speed trace off of the first plot to make a point. It just doesn't exist. There was no separate speed sensor on board in that run, and with a cadence sensor and knowing the gear ratios, there's no need for one. Wheel speed and cadence are the same "signal", just taken at different parts of the mechanism. As long as the chain doesn't "slip", or something crazy like that, the ratio between cadence and wheelspeed is fixed.


lightheir wrote:
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.

Wheel speed and cadence are the same "signal", just taken at different parts of the mechanism. As long as the chain doesn't "slip", or something crazy like that, the ratio between cadence and wheelspeed is fixed.


lightheir wrote:
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.

Frank? Is that you? ;-)


lightheir wrote:
Nobody correlates cadence to power as you are doing....I never use cadence as a surrogate for power, ever, and I don't know anyone who does as well.

That doesn't mean that using cadence as a surrogate for wheelspeed isn't correct. It's simple math...and recognizing that it's a chain drive with fixed ratios. Holding cadence constant is a LOT easier IME than trying to hold wheel speed constant when one is doing testing like I was describing above.

BTW, are you aware that RChung consistently looks at speed data and cadence and is able to back-calculate the gear ratios? That wouldn't be possible if one couldn't calculate speed knowing cadence and gear ratio.

http://anonymous.coward.free.fr/...ng/testprotocol.html

http://anonymous.coward.free.fr/...ents/components.html


http://bikeblather.blogspot.com/

First page Previous page 1 2 Next page Last page  View All  
 
 
 



New Product Intros
Is there a specific event you most closely associate with new product coverage and intros?
Sea Otter
Eurobike
Interbike
Hawaiian Ironman
I'm oblivious