Respoking a Power wheel.

timjames

I need to respoke my Powertap SL+ in my rear wheel, due to a couple of nipples going and a spoke breaking. I have heard that I will need to have it re-calibrated due to a different tension coming from the new spokes. Can you tell me if this is true or not. Many thanks.

doyler78

Sounds like rubbish to me as they are widely sold on their own ie not as part of a wheel. I think in that case they can't have that sort of issue or they just wouldn't sell them that way. I've checked the manual and all it has is details of how the wheel should be laced. I could of course be completely wrong.

Anonymous

Rubbish...

No issues with doing it at all...

hopper1

+1 for rubbish...

You'd only need to do recalibrate if it measured power from the rim, which it doesn't...

Alex_Simmons/RST

Rebuilding the wheel won't change the calibration of the hub.

Nevertheless, you should perform a calibration check anyway as that's just good practice.

timjames

Thanks to all for your advice. I recalibrate with my Garmin 500 before every ride anyway. Thanks.

doyler78

timjames wrote:

Thanks to all for your advice. I recalibrate with my Garmin 500 before every ride anyway. Thanks.

It's not a "proper" calibration that the garmin 500 is doing. You need to hang an accurate weighted heavy object on your pedals to test that what torque is reported (which you will need ant+ stick or lyc to do as the garmin also doesn't give you that info either) matches what the atual torque is to within spec ie +/- 1.5%.

Alex_Simmons/RST

timjames wrote:

Thanks to all for your advice. I recalibrate with my Garmin 500 before every ride anyway. Thanks.

As doyler said, that's just a torque zero check, not a calibration check. They are totally different things.

An analogy:
Bathroom scales that read -2kg when no weight is on them - you reset them to read 0kg with no weight on them. that's analogous to torque zero setting for a power meter.

calibration - the scale read 0kg with no weight on them and then you check it again with a known mass so that it also reads (say) 50kg with a known 50kg weight. that's analogous to validating the power meter's "slope" calibration.