Hey guys—i hate asking this question—but i just set up my PT Pro and i went for a ride with my wireless bike computer (ciclosport 434) still on the bike and my powertap speed and distance was about twice what my old/correct computer was reading. If my Ciclosport read 16 mph the PT was reading like 32. Also my power numbers seemed off—i.e. too high. I treid switching to km just to see what happened and the numbers were even higher (which makes sense). I zeroed out the torque readings, i set the wheel circumference to 2096 (which is what the PT manual says is the circumference of a 700x23 tire).
But then it gets weirder. I did a hard sprint and the speed readout on the PT went up and up to like 40-50 mph (obviously wrong) and then they dropped and equaled the readings from my ciclosport at 26-27 mph and the power output numbers dropped as well back to a normal amount like 300 watts for 26 mph or so.
What the heck is going on? I read on a forum not to tighten the zip ties down really tight (which i did) so i just went and took off all the zip ties and took my bike for a spin the parking lot and the numbers were still twice as normal.
The only thing i havent checked was to take off the ciclosport—any way that the frequency from the wireless ciclosport is screwing up the PT readings?
I have had some problems with interference with my PT, I know that my niterider lighting systems will screw it right up. I suggest try taking the ciclosport transmitter off the bike to see what happens. I have left my cateye cordless on my bike, without any problems. If that doesnt work the POS will need to go back.
The PT’s are great when they work, but they do seem to have some reliability issues. I am now on my 3rd wiring harness and second head unit. Cross fingers it has worked well the last 4 months.
Maybe you got a defective unit? Mine worked fine out of the box. The only problem I ever have is sometimes the heartrate monitor gets blanked out when I ride near power lines.
The PT Pro harness seems to be REALLY finicky. I have one on my Kestrel Talon SL TT/Tri bike that works as advertised. I have been through three harnesses on my Specialized E5 SLX road bike and still have yet to get one that works with any degree of reliability. This has proven extremely frustrating, particularly because I prefer to do much of my recovery and long training at this point in the season on my road bike. I use the same head unit and wheel on both bikes, so the only difference is the harness. . .oh and the carbon frame vs the aluminum frame. But this is the THIRD harness. . .hmmmmm. I have even used thin foam under the head mount and receiver in order to isolate them from road buzz. This hasn’t helped either.
To my electronics trained eye. . .the wires used in the PT harnesses leave a tremendous amount to be desired. They are not shielded, leaving them prone to electromagnetic interference. They are thin and fragile meaning that they cannot be strapped very tightly with the zip ties without cutting them.
My latest theory on why the harnesses haven’t worked on my road bike is that I’ve had to wrap the receiver wire slack much more on the brake cable in front. I’m theorizing at this point that this has cause a slight induction effect in the wire, impeding the signal transmission enough to interrupt the signal flow. My unit currently only works for about 10-20 seconds at a time before dropping out to the dreaded dashes.
I was so mad the other day I came home and switched the head and wheel to the Kestrel to finish a short 20 mile recovery ride. Anyone who’s read my reports on the Hed aerobars I have on that bike will know this isn’t my preferred bike to ride slow. The bars are less than optimal for riding extended periods on the horns, which mimics a relaxed brake hood position on the road bike.
Ahh. . .the frustration. PLEASE, Graber. . .REDESIGN THE HARNESS TO MAKE IT MORE RELIABLE!!!
