Cadence - Powertap

tomUK said:

for those of you who've fitted the cadence sensor on the powertap - are the readings much different to those obtained from the hub? I'm wondering if it is worth installing this option.

Thanks

The hub readings I have seen from my old style pro and SL are all over the place. I don't know if the average reading over a period of time is correct or not.

The wired cadence readings were reasonable and consistent. Don't actually know if they were correct. It stopped working anyway and I just removed it.

TF

tomUK said:

for those of you who've fitted the cadence sensor on the powertap - are the readings much different to those obtained from the hub? I'm wondering if it is worth installing this option.

Thanks

For me, the hub cadence is (amazingly) usually right. It has some noise in it, so jumps around a bit here and there, but it's usually right. It's close enough in my case that I can't imagine anyone wanting the wired cadence. However, it seems people vary on this, so it might depend on you/your bike/?

lanierb said:

For me, the hub cadence is (amazingly) usually right. It has some noise in it, so jumps around a bit here and there, but it's usually right. It's close enough in my case that I can't imagine anyone wanting the wired cadence. However, it seems people vary on this, so it might depend on you/your bike/?

Here is a pic of a file using the hub (I hope). I doubt if I spent much (if any) time over 100 RPM on this ride - certainly nothing over 110. - TF

EDIT: Added a second pic of the wired cadence. - TF

tomUK said:

for those of you who've fitted the cadence sensor on the powertap - are the readings much different to those obtained from the hub? I'm wondering if it is worth installing this option.

Thanks

If you are a smooth pedaler the hub cadence readings will be wild. OTOH, if you mash your gears, the readings will improve. The hub seems to calculate cadence based on variance in power during a pedal stroke.

I compared my hub sensed cadence to a polar cadence sensor when I first got my 2.4 and they were the same. I didn't bother to buy the wireless cadence.

My cadence readings on the hub are all but useless.

To "confirm" what Piotr said, my cadence evens out when I'm climbing hard. Using the hub cadence will fill in the 2-3 strokes of power before the pedal cadence sensor starts counting, but it typically gives you 2-3 rotations @ a wildly inaccurate high RPM.

NomadVW said:

My cadence readings on the hub are all but useless.

I have the same experience as NomadVW. Hub cadence for me isn't very accurate.

Here's a comparison I made a while back:
http://cyclingforums.com/showpost.php?p=3193084&postcount=50

Just a note, when using the cadence sensor I also saw anomalies when doing sprints if the PowerTap CPU was sent to "Pedal-Hub". But changing the setting to "Pedal Only" seems to have fixed this. This option can be found in Setup Menu #4.

NomadVW said:

My cadence readings on the hub are all but useless.

To "confirm" what Piotr said, my cadence evens out when I'm climbing hard.

1. The accuracy of hub-based cadence depends both on the rider and the situation.
2. In general, even if cadence were accurate, it's pretty useless. Cadence is a red herring.
3. If you're really, truly, interested in cadence, it's often possible to recover the "true" cadence.
4. You shouldn't be really, truly, interested in doing that.

RChung said:

1. The accuracy of hub-based cadence depends both on the rider and the situation.
2. In general, even if cadence were accurate, it's pretty useless. Cadence is a red herring.
3. If you're really, truly, interested in cadence, it's often possible to recover the "true" cadence.
4. You shouldn't be really, truly, interested in doing that.

Please expound on this comment. I'm very curious to hear how you've arrived at this conclusive statement. Personal experience, anecdotal evidence???

tonyzackery said:

Quoted post said:

2. In general, even if cadence were accurate, it's pretty useless. Cadence is a red herring.

Please expound on this comment. I'm very curious to hear how you've arrived at this conclusive statement. Personal experience, anecdotal evidence???

Personal experience, anecdotal evidence, literature review, and data analysis.

RChung said:

Personal experience, anecdotal evidence, literature review, and data analysis.

Uh, ok, that explains everything...

tonyzackery said:

Uh, ok, that explains everything...

Not that RChung is the only person that thinks that.

FWIW, when i first got each new model of Power Tap, i'd compare the hub only readings with an actual computer that measured cadence (e.g. SRM, Ergomo). While the instantaneous cadence could often be off, i used to find that the average for a ride was always within 1 or 2 revs/min compared to the actual cadence meter. I then pretty much promptly forget about cadence.

Ric