PowerTap SL lot of data drops

carmol

Hi

I've had my PT SL now for around half a year (since end of august 2006). It worked to my satisfaction till the end of december 2006.

Since that time occasionally problems arose: sometimes - the PT indicated a too little power during the first seconds and afterwards no power was shown. After perhaps 20 to 40 minutes all readings came back and seemed reasonable (means everything worked correctly again, AFAICT).

On other occasions, the readings for power and speed were obviously wrong (e.g. speed of 15 km/h where rather 30 km/h would have been correct), but the pedaling frequency and HR announcement were correct (RPM by hub). Last weekend the power readings failed again in close proximity to power lines (railway, telephone etc.). Is there a possible relationsship with the weather? The weather was cold (~8 C) and short before a violent rainstorm.

Of course, I've already changed all batteries, but to no avail.

Is this a common problem with a well known solution or do I have to contact Saris?
Thanks for your solutions and answers.

Please excuse my English, I'm not a native speaker.

ric_stern/RST

My SL failed for the first time in 18 or so months on Saturday. At first i was convinced that it was the receiver kit (the cable) that was broken or damaged as i was getting an intermittent signal to the CPU. I then suspected that the CPU was damaged.

Luckily, as a dealer, i have a few of these in stock and was able to check! I then discovered that with a different cpu and receiver kit i was still getting an intermittent signal. At this point i suspect my hub was broken, and was pretty upset

However, luckily, i had a spare in stock and tested that (not in my bike - just next to it). This worked fine and therefore showed that my SL was broken. I took the wheel out and inspected it. It took a while but i realised that the axle/cones had come undone on my SL hub. I tightened them up and my SL hub worked fine. I checked that the torque was reading correctly and it was.

So, after checking your other kit, check to see if the cones/axle are all tightly done up. It worked for me!

ric

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carmol

Indeed, my rear axle is not tightly done. I wanted to fix this but forgot...

Thanks for the advise!

goneskiian

Ric,
Do you find that loose cones/axle cause the power to drop out intermittently during a ride? I've been having this issue quite a bit lately. I changed the batteries in the hub and cpu. The issue persisted so I changed out the cradle/pickup system (I had a brand new one as a spare) as I thought it might be an exposed cable or loose connection and it's still dropping out quite frequently.

I've thought about cleaning the contacts and perhaps using some dielectric grease to keep water away from the contacts as well (something I remembered reading here). I'm not sure what to use to clean the contacts though.

Anyway, thanks for your input here. You've got a lot of great experience and I for one am happy you're willing to share it.

Cheers!
-Ian

ric_stern/RST

it did on the friday. took a good while to get a good signal. then on saturday it was kaput!



i believe that alcohol, or something like whisky is good at cleaning the contacts.



no probs. glad to help
ric

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carmol

After all, I think I know now, where my problems with data drops came from. Probably I had a problem with vibrations. My shark finn was mounted without anything to minimaze vibrations. After putting a little bit of an inner tube between the seat stay and the receiver, my powertap worked correctly again.

Can anybody confirm my experience?

goneskiian

Doesn't the shark fin receiver already have a bit of rubber to isolate it?

I guess that's not enough. I mounted my receiver on the underside of the chainstay and didn't crank down the zip ties too hard so it's just a little loose. Not enough to slide forward or backward but hopefully enough to keep it isolated from vibrations.

So far, I think my problem was with the loose hub. That seems to have fixed it. Now, about that HR function....

I know, I know. Just through the chest strap in the garbage. Trust me, I'd like to but my coach of 6 years likes to see HR data, and I'd rather give him spotty data than have to attach another piece of hardware to my body or bike.

Cheers!
-Ian

mhkang

Am I experiencing data drops? Mac version of poweragent has my last workout broken into 30 sec- 4min blocks. Almost like I was doing intervals. Seems like the entire 1.5 hour ride was captured, but I can only look at each individual capture moment. Can I merge the 30-40 blocks into a complete ride?

I am using very old powertap hub with newer powertap cpu.

rayhuang

I have all new everything in my SL (sharkfin, cpu, torque tube, bearings) and after two months of nothing worse than HR problems everything has been decent. Not great as I always have the occasional drop-outs. Well fast forward to the last 5 rides and I started to get drops (speed/wattage). I lose comm signal and of course watts and then it comes back. Some rides i may get one or two in 1.5 to 2 hours and other rides 16 to 20 in that same time span. I checked batteries with a digital voltmeter and voltage in all cells is fine and I replaced some anyways.

I have been in constant communication with Saris and they had me try this and that. Nothing is helping and the fact that I chnaged nothing and am starting to have more and more problems AGAIN says something is failing.

Am I correct in thinking that I am losing another torque tube? lats time these problems starting occuring I eventually lost comm signal for godd and I had to send the wheel to Saris and they did a great job for me replacing parts.

I hate to say this, but I almost wish I had the $3400 for a SRM now!!

Ray

rayhuang

Yes-combine them all before opening in power agent.

rayhuang

To answer my own question, I had two things going on. Battery in CPU was 2.5 months old (100 to 125 hours max) and when I started to have drop-outs I played with how close the sharkfun was to the hub. Closer seemed better, but still having drop-outs. On a bad recommendation form Saris CS they said try moving the receiver further away and that made for more dropouts.

After changing batteries I still had dropouts, but less and my receiver was a little further away then normal. I moved it not only to where it used to be when I never had dropouts, but another 5mm or so closer. Its less than an 0.5" (13mm) from the hub (outer circumference of black cover).


Very simple solution is dont worry what the display looks like, just change batteries every 100 hours of usage or at the first sign of losing comm signal and keep that sharkfin as close as you can (if you have a SL). I am pretty sure my problems are solved as I had half of a workout without drop-outs (after moving receiver) and one perfect 1.5 hour session without a single drop-out.

Ray

Terry Ferguson

I would bet that it is nowhere near that simple and that you will continue to have problems. - TF

rayhuang

Probably!! 3+ hour ride tomorrow with new batteries in HR strap, CPU and good ones in the hub. Will be cold and windy so it will be a touigh day for the old PT!!

The only thing I wish I had was some of that gel for the HR strap to see how much improvement I get.

I have my first real test of the season in two weeks (TT) and I sure hope that the PT works then!! COuld be 170 entrants for the TT and I am basing my whole pacing strategy on the data I see on the PT screen. I have already prepared my mind for the fact that I may roll off and anyone of the data may be missing (HR, Cadence, Wattage and Speed) and to not freak out when it happens. PLan B??? Anyways-I always blab on and on-my point being I am scared that after 10 months of training (8 or 9 with a PT) may go down the toilet so to speak because of this unit. I should borrow a HR monitor from someone locally justin case and bring my cateye from my other bike just in case!! Not that I'l have time to screw with it!!

Ray

rayhuang

fwiw-not one data drop on a 4 hour ride today-whew!!