Power Tap Recall?



Aztec

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Jul 8, 2003
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I ordered a 28h Power Tap Pro a month ago. They were out of stock just about everywhere in the US. Then they came in, but were quickly recalled by Cycleops, on the grounds that they are mis-calibrated. Anyone else hear this? I've found another shop that carries them, and has one in stock, but I'm concerned about the whole recall issue now (that may be one that needs the recall).
 

acoggan

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Jul 4, 2003
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Not so much a miscalibration, but a gross error in calculated power due to a running change in the design of the reed switch that counts hub revolutions. Solving that is what has apparently held up production for a while, but I heard/read somewhere that they were close to clearing up the back-log.

Sorry, but I don't know how you might tell whether the other one you've located is subject to this recall. I'm sure, though, that Graber could tell you, so maybe call them for the info (serial number or whatever) and then re-contact the shop?
 

tomUK

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Oct 20, 2003
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Is there anyway to tell if the unit I have is reporting the wrong figures?
 

acoggan

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Jul 4, 2003
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Originally posted by tomUK
Is there anyway to tell if the unit I have is reporting the wrong figures?

I've not played with one of the bad hubs, but I believe that those who have run into this particular problem (after sending their hub in for repair) have found that the speed is grossly off as well. So, if you're confident that you've entered the correct wheel circumference yet the speed is reading way too high, then there's a good chance you've got a bad hub. If not, then I'd guess that it is probably okay.

If you really want to be certain, here's what to do:

1) put your bike in a trainer or some other stationary stand
2) shift your lowest gear
3) put the computer in torque mode (as if you were going to zero it)
4) with the cranks perfectly horizontal, apply a known force (e.g., your body weight - which requires excellent balance!) to the pedal

The torque that is reported by the computer should match the torque that is applied, once you correct/account for the crank length, the gear ratio, and get everything in the proper units. (See the FAQ of the wattage list on topica.com for more details of this "stomp test".) If it does, and the speed/distance reading is also correct, then the power data calculated from these two values (i.e., torque and rpm of the wheel) will also be correct.
 

tomUK

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Oct 20, 2003
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Thanks Andy -

The torque is spot on - 507 with the beefcake misses (127.6) stomping!

Not sure the speed is right, but I suspect it is. I know for sure the circumference is correct as I used an EXTREMELY accurate method to measure it.

How do I check it anyway - shout at passing cars 'what speed are you clocking me at?'

Cheers,
Tom
 

velomanct

New Member
Dec 21, 2003
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tom,
ride a short route around your house on your bike and then in your car, compare the distances.
that only works if you know your car speedo is right.
i have been in cars that are off by 10mph.

or you can ride with some buddies and compare speeds while riding along side each other.