Rotor 3D Crank with Q-Rings

[jdtate101]

Interestingly I just came across this conversation on the web:

http://forum.slowtwitch.com/gforum.cgi?post=4322434;search_string=power2max;

It seems to indicate that possible errors for elliptical rings in power readings are due to cadence reed switches and velocities of rotation not being uniform. However the p2m doesn't use a magnet, rather it uses an algorithm to calculate the cadence, which it why they may say it doesn't require "slope" calibration when you change rings....

 

[Rob3rt]

Interestingly I just came across this conversation on the web:

http://forum.slowtwitch.com/gforum.cgi?post=4322434;search_string=power2max;

It seems to indicate that possible errors for elliptical rings in power readings are due to cadence reed switches and velocities of rotation not being uniform. However the p2m doesn't use a magnet, rather it uses an algorithm to calculate the cadence, which it why they may say it doesn't require "slope" calibration when you change rings....

Yes sounds something like the guy said, he was very helpful.

Regarding cadence measurement and power meters, presently I am thinking about how to best implement my Quarq, the Quarq needs me to install a cadence magnet, this is fine. The trouble shooting says one should remove existing cadence sensors, however, I want to keep my rear wheel speed/distance measurement with my Garmin as it is more accurate, instantaneous and also used on the turbo, I wonder if I just pull the cadence magnet from my crank arm that the speed data will stream from the GSC-10 to the head unit and the cadence will come from the Quarq? So I can have best of both. Here's to hoping!

 

[jdtate101]

Assuming you have a Garmin head unit, you can manually set a bike sensor as speed only and program in the ANT+ ID, so that it only pics up that part. I think you don't need to register the cadence part of the Quarq on the head unit as it should transfer as part of the power protocol.

 

[Rob3rt]

Yes, the cadence comes with power from the Quarq, but the GSC-10 also transmit's speed and cadence data, given the Garmin has 2 inputs for cadence, this can apparently make the power reading read over. What I want is the GSC-10 to only provide speed data and not cadence, I guess.

Quite frankly, I have never fiddled with my Garmin in 3 years, fit and forget, not even changed the battery (oddly it has lasted a long time, as I ride a lot ~10 hours a week).

 

[jdtate101]

Yes, the cadence comes with power from the Quarq, but the GSC-10 also transmit's speed and cadence data, given the Garmin has 2 inputs for cadence, this can apparently make the power reading read over. What I want is the GSC-10 to only provide speed data and not cadence, I guess.

Quite frankly, I have never fiddled with my Garmin in 3 years, fit and forget, not even changed the battery (oddly it has lasted a long time, as I ride a lot ~10 hours a week).

What you do is delete the GSC-10 from the sensor list, manually add just a speed type sensor and program in the GSC-10 ANT ID. The cadence should come over automatically when you register the Quarq.

 

[Rob3rt]

Thanks mate, will do just that when I get round to sorting this!

 

[Rob3rt]

Quick comment back, thanks for your advice, turned out to be much simpler than expected, no need for manual entry of the Ant+ ID's etc, I installed the Quarq and the GSC10. I left the cadence magnet off the crank arm so the GSC10 was only measuring speed, I crossed my fingers that it would not send out cadence data rather than send out a stream of zero's or that it would send out a "no data" signal and the Quarq would take precedence as it had that data in its data stream. Well one of the 2 happened (or something else equivalent) and speed is coming from my GSC10, Cadence from my Quarq (power and power balance ofc also coming from the Quarq) and HR from the HR strap, all spot on working fine via auto detect!

One thing I have noticed though, I wonder if you could test with your p2m, if I have a HR monitor paired, but not present (say I go out without it or something), when I send the calibrate signal from Garmin to Quarq, it does not calibrate. it goes into a state of indefinate waiting for a response from the power meter, I have to go into the HR options and turn HR off to calibrate. If the HR monitor is present however, it works fine.

 

[jdtate101]

That's sounds odd as the HR is nothing to do with the PM, unless it's a quirk of the Garmin (which model are you using??). Do you have to zero on the Garmin on every ride, I thought with the quarq you back pedalled 4 times to zero??? I think you actually have to turn the cranks to power on the system before you then calibrate at the head unit, otherwise the quarq is not awake. I'll try the HR missing thing with my p2m and see if I can replicate it.

 

[Rob3rt]

I am using a Garmin Edge 500, you should zero the Quarq when dismounted and the drive side crank in the 6 o'clock position at the beginning of each ride and then you can update it by back pedalling 4 times. The Quarq was definatelly awake when the paired but non present HR monitor caused said issue.

I keep forgetting to zero it, need to get into the habit, keep remembering like 10 minutes in, lol.

 

[jdtate101]

This is where the p2m and quarq differ. The p2m will zero automatically whenever I freewheel and I can manually zero at the start of a ride by back pedalling. It's worth zeroing during the ride at various points as most PM's suffer from a small amount of thermal drift. This is not an issue when doing a ride as you will naturally freewheel at points, but on long climbs you cannot do that, and most have a thermal sensor to help, but it never eliminates it completely. The only time I really have to zero the P2M manually is when I'm doing a roller session and have just brought the bike indoors. There's no way I can free wheel on the rollers, so I have to do a small warm up (5mins), then stop for 1 min to zero, then do my 60mins session.

 

[ufkacbln]

Elliptical chainwheels have been around since the late 1890's so it's interesting that manufacurers are still coming out with them. Shimano tried it in the late eighties but chose to drop it for whatever reason. I have one on my Dawes and to be honest I can't tell much difference. It's interesting to read your review though.

There were some pundits (Mike Burrows amongst them) that reckoned the Shimano Biopace were 90 degrees out!

Until recently they were also custom made by Highpath Engineering - their page on oval chainrings is enlightening

 

[Ricey155]

re light the thread

I've been really impressed with the Q rings only set at basic position 3 but i've upped by cadence from low 80's to 87/88 and feel so much easier up hill, done about 500 miles and feel more and more fresh after every ride same speeds less effort