powertap- speed/watt dropoffs

velomanct

yet another issue with the powertap (pro model). speed/watts are dropping off every minute or 30 seconds when in use. the screen goes blank with dashes and then returns to normal. i replaced the battery in the cpu, and the transmission icon is NOT flashing so the hub batteries should be okay.
also, I got some real crazy readings today, like 21881watts max and 385mph.
i have not ridden in wet conditions with the wheel in a long time.
I did ride in the rain yesterday WITHOUT the powertap hub/wheel, only the computer and receiver.
I also just did a stomp test and the torque is within 1% accuracy.
I'm still thinking the torque tube is bad. any thoughts?

__________________
"friendship, family, religion. These are the three demons you must slay if you wish to succeed in business!" -Mr. Burns
The faster you go, the fewer passing cars

Woofer

Do you have a friend with a PowerTap? Try to make one if you don't. Substitute a known good wheel with yours and see what happens. Then try different CPU's with your wheel and see what happens. A have several powertaps so it makes diagnosing much easier. slightly OT, SRM recommends that people purchase two wiring harnesses so they can diagnose problems. It's just like figuring out problems with PC's, the easiest thing to do is start substituting known working components with one of yours and see what is happening.

It certainly sounds like a bad torque tube, though. Have you contacted Graber? They are very good about helping diagnose these problems.

velomanct

i had bought another reciever/cpu harness earlier for another bike, but it didn't even work. I followed the instructions for the placement of reciever. it seems that some days the powertap is just fine with no problems, then once in a while it goes crazy. normal weather too.
i'm going to see how it works today, then contact graber.

__________________
"friendship, family, religion. These are the three demons you must slay if you wish to succeed in business!" -Mr. Burns
The faster you go, the fewer passing cars

rule62

Your dashed line description and mid-ride crazy watt readings are the exact same problems that I have been having with a new SL. New CPU, new harness, different install, burning incense, chanting to the cycling gods...nothing has worked to fix the problem. Saris is taking the SL's back and sending out Pro's until they come up with a fix. I would contact them about your problem. It should sound pretty familiar.

rickmoll

I know that CycleOps is having torque tube related problems with the SL hubs, but since you have a Pro, I wouldn't yet assume you have a tube problem. Besides a tube problem wouldn't expain the inflated speed reading. Both the data dropouts and inflated readings can be caused by data transmission problems with the hub, which *could* be due to failing batteries. I know you already replaced the cpu battery, I would replace the hub battery as well, just to make sure.


Rick Moll
rickmoll@earthlink.net
http://rick.mollprojects.com

velomanct

powertap worked perfectly today, on my 30 min recovery ride, as opposed to my 3hr time trial yesterday, go figure

__________________
"friendship, family, religion. These are the three demons you must slay if you wish to succeed in business!" -Mr. Burns
The faster you go, the fewer passing cars