PowerTap SL Intermittent Data

[Bruce Diesel]

I have a PowerTap SL built into Zipp 404's. Today was my first race with them and I have got some serious data drops. Every now and then the computer display get's a line of dashes and shows no data.

I have just downloaded the data there are serious gaps. I know the computer works fine because I have been training with a PowerTap Pro on the same bike with no problems.

The transmission icon is not flashing - could it still be a battery problem?

 

[F1_Fan]

I have a PowerTap SL built into Zipp 404's. Today was my first race with them and I have got some serious data drops. Every now and then the computer display get's a line of dashes and shows no data.

I have just downloaded the data there are serious gaps. I know the computer works fine because I have been training with a PowerTap Pro on the same bike with no problems.

The transmission icon is not flashing - could it still be a battery problem?

1) Do the drops correspond to periods of coasting (such as decending)? You may need to mount the sensor with a piece of foam underneath it. The SL's freehub transmits (through the frame) enough vibration to mess with the sensor.

2) There's a chance that you were riding beside a rider with other wireless transmitters and those were interfering with the SL.

 

[RapDaddyo]

This is a major problem with the SL compared with the Pro. There's a thread on this forum about it, but the search function is temporarily disabled. Try searching in this forum with a string that includes "PT" and "SL" and "dropouts" and you'll probably find it. This is testable on a trainer or repair stand. You don't need to unwire your receiver. Just get a variety of pieces of foam or other spongy material and a bunch of the skinny cable ties. Snip the cable ties on your receiver and you're ready to test. Get the wheel turning at a good speed and freewheel it (or even backpedal) to get the pawls screaming. You'll get the dropouts -- lost transmission icon. Keep experimenting with stuff between the receiver and the seat stay until you can't get it to drop the transmission icon anymore. And then tell us what worked.

 

[Bruce Diesel]

This is a major problem with the SL compared with the Pro. There's a thread on this forum about it, but the search function is temporarily disabled. Try searching in this forum with a string that includes "PT" and "SL" and "dropouts" and you'll probably find it. This is testable on a trainer or repair stand. You don't need to unwire your receiver. Just get a variety of pieces of foam or other spongy material and a bunch of the skinny cable ties. Snip the cable ties on your receiver and you're ready to test. Get the wheel turning at a good speed and freewheel it (or even backpedal) to get the pawls screaming. You'll get the dropouts -- lost transmission icon. Keep experimenting with stuff between the receiver and the seat stay until you can't get it to drop the transmission icon anymore. And then tell us what worked.

Okay, tried these suggestions with no luck - am busy talking to the dealers about the problem. When it is diagnosed, I will post the problem.

Being an electronic engineer - I suspect there is maybe a dry joint on the PC board inside the hub, or the battery connections sometimes fail due to the motion. I have tried reseating the batteries carefully but no joy.

 

[Woofer]

I have a PowerTap SL built into Zipp 404's. Today was my first race with them and I have got some serious data drops. Every now and then the computer display get's a line of dashes and shows no data.

I have just downloaded the data there are serious gaps. I know the computer works fine because I have been training with a PowerTap Pro on the same bike with no problems.

The transmission icon is not flashing - could it still be a battery problem?

SRM recommends people buy an extra harness for debugging hardware problems and I think the same advice holds true for Ergomo and PowerTap. I have multiple wheels and harnesses and it's really easy to diagnose problems with extra hardware.

 

[jbvcoaching]

I have a PowerTap SL built into Zipp 404's. Today was my first race with them and I have got some serious data drops. Every now and then the computer display get's a line of dashes and shows no data.

I have just downloaded the data there are serious gaps. I know the computer works fine because I have been training with a PowerTap Pro on the same bike with no problems.

The transmission icon is not flashing - could it still be a battery problem?

How cold was it? My experience (over 5 different SL hubs) is that SLs have dropouts below around 35'F. Most people are OK for racing, but for many people this makes the SL a poor choice for a training hub.

You put fresh batteries in the hub?

Receivers seem to be a bit more vibration sensitive when using SL hubs, as others have noted, but as long as you have a bit of rubber between the receiver & the frame that's probably not it.

Don't bother with a dealer, they'll likely be as much help as an internet forum . Call CycleOps tech support directly.

 

[peterwright]

Okay, tried these suggestions with no luck - am busy talking to the dealers about the problem. When it is diagnosed, I will post the problem.

Being an electronic engineer - I suspect there is maybe a dry joint on the PC board inside the hub, or the battery connections sometimes fail due to the motion. I have tried reseating the batteries carefully but no joy.

Just to clarify, you havent said whether the drop outs are when coasting only or if you get them while pedalling ?

 

[Bruce Diesel]

Okay, I have resolved the problem. I reseated the receiver, on a nice thick piece of rubber. I moved the receiver as close as possible to the hub, and I reseated the batteries (again).

Could have been any one of these, but it is working now!!

I suspect is was the receiver distance from the hub that was borderline. I measured around 3.5cm between the receiver and hub - which I thought would be in the within the 3" limit - must have been right on the edge.

 

[RapDaddyo]

Okay, I have resolved the problem. I reseated the receiver, on a nice thick piece of rubber. I moved the receiver as close as possible to the hub, and I reseated the batteries (again).

Could have been any one of these, but it is working now!!

I suspect is was the receiver distance from the hub that was borderline. I measured around 3.5cm between the receiver and hub - which I thought would be in the within the 3" limit - must have been right on the edge.

I have also made a major change in my SL installation related to dropouts. I was off the bike all week last week (cold virus) and decided to clean my bike top to bottom, including removing/replacing all the cable ties. Since I had the receiver off, I decided to experiment with lots of materials to use between the receiver and the stay. Eventually, it occurred to me that I shouldn't mount it on the stay at all, but rather I should hang it from the chain stay as far back toward the hub as possible. I did this and tested it extensively on the trainer. It worked perfectly and I could not get dropouts no matter, even backpedaling while the pawls were screaming. When I rode two group rides this past weekend, the installation continued to work perfectly on the road. I had rough roads, multi-minute freewheelilng descents, the works. Not one single dropout. I'll take a picture and post it in a new thread on this topic, but I now think this is the way to go with this quirky receiver. At the moment I am using zip ties, but they are more suited to cinching things tight rather than hanging them free. I'm also going to fool around with a sort of harness with a canvas-like waterproof material and velcro, something quickly and easily removable for cleaning.

 

[Bruce Diesel]

I have also made a major change in my SL installation related to dropouts. I was off the bike all week last week (cold virus) and decided to clean my bike top to bottom, including removing/replacing all the cable ties. Since I had the receiver off, I decided to experiment with lots of materials to use between the receiver and the stay. Eventually, it occurred to me that I shouldn't mount it on the stay at all, but rather I should hang it from the chain stay as far back toward the hub as possible. I did this and tested it extensively on the trainer. It worked perfectly and I could not get dropouts no matter, even backpedaling while the pawls were screaming. When I rode two group rides this past weekend, the installation continued to work perfectly on the road. I had rough roads, multi-minute freewheelilng descents, the works. Not one single dropout. I'll take a picture and post it in a new thread on this topic, but I now think this is the way to go with this quirky receiver. At the moment I am using zip ties, but they are more suited to cinching things tight rather than hanging them free. I'm also going to fool around with a sort of harness with a canvas-like waterproof material and velcro, something quickly and easily removable for cleaning.

I also considered moving it to the chainstay. My only concern was that it wouldn't be protected there. I was concerned that it could get damaged while changing a wheel. Every now and then the bike touches the ground without the rear wheel on - shouldn't, but it does happen.

 

[peterwright]

I also considered moving it to the chainstay. My only concern was that it wouldn't be protected there. I was concerned that it could get damaged while changing a wheel. Every now and then the bike touches the ground without the rear wheel on - shouldn't, but it does happen.

I have had mine on the chainstay for over a year now with no problems - makes for a neater installation.

 

[JIM WV]

I was plagued with this problem early on as well. My experience was that different types of insulating materials made a big difference. I first tried using stacks of cut inner tube shims to no avail. I finally found that a thick chunk of foam rubber worked the best. May play around with RDO's hanger solution.

 

[RapDaddyo]

Here's my free-hanging installation. I used 2 of the wide cable ties from Saris through the round holes in the receiver. They are not pulled tight because I wanted to avoid vibration transfer from the chainstay. The third tie is pulled tight to prevent the receiver from sliding forward away from the hub. Because the receiver is hanging free, it would simply rotate if I were to lower the frame to the ground, so I don't think it would be damaged. I plan to make a more elegant solution out of black canvas waterproof material and velcro. Will post a pic when it's done.

 

[jbvcoaching]

Here's my free-hanging installation. I used 2 of the wide cable ties from Saris through the round holes in the receiver. They are not pulled tight because I wanted to avoid vibration transfer from the chainstay. The third tie is pulled tight to prevent the receiver from sliding forward away from the hub. Because the receiver is hanging free, it would simply rotate if I were to lower the frame to the ground, so I don't think it would be damaged. I plan to make a more elegant solution out of black canvas waterproof material and velcro. Will post a pic when it's done.

Apparently no issues with it swinging into the spokes? I guess the third (tight) tie takes care of that...How come it's turned around, with the nub side away from the hub?

Separate issue: Anyone have a good source for long, thin zip ties? I know you can just use two short ones linked together, but it's not as clean looking to me.

 

[RapDaddyo]

Apparently no issues with it swinging into the spokes? I guess the third (tight) tie takes care of that

No problems. Gravity positions it correctly and the third tie is there to keep it from sliding forward.

How come it's turned around, with the nub side away from the hub?

To put the receiver (flat side) facing the hub. If there was any pressure on the wire to the handlebar mount, I would worry about it crimping, but the 3rd tie prevents that.

 

[cbjesseeNH]

My PTPro has been giving me drop-outs too on the Computrainer - seemed fine on-road this past Fall (it's new). I've just done one experiment with vib-proofing, adding a 1/8" slab of Sorbothane, but still get drops. Must be frequency dependent?

I hear Cycle-Ops has a new mount kit, with clear tapes and fewer zips (available at Home Depot, Lowes, etc., for above inquiry). Perhaps a new harness is in order anyway, to be mounted on the chainstay this time instead of present seatstay location.

 

[Bruce Diesel]

My PTPro has been giving me drop-outs too on the Computrainer - seemed fine on-road this past Fall (it's new). I've just done one experiment with vib-proofing, adding a 1/8" slab of Sorbothane, but still get drops. Must be frequency dependent?

I hear Cycle-Ops has a new mount kit, with clear tapes and fewer zips (available at Home Depot, Lowes, etc., for above inquiry). Perhaps a new harness is in order anyway, to be mounted on the chainstay this time instead of present seatstay location.

Is there any other RF equipment on the system - sensors etc. I believe that there is often interference.

 

[zaskar]

Does anyone here get drop outs for 1-3 seconds? i have my receiver on a nice piece of foam. in a 4 hour ride i get about 10-15 sec of missing data, i never see ----- probably because it doesn't drop long enough. im thinking RF interference?

 

[Alex Simmons]

Does anyone here get drop outs for 1-3 seconds? i have my receiver on a nice piece of foam. in a 4 hour ride i get about 10-15 sec of missing data, i never see ----- probably because it doesn't drop long enough. im thinking RF interference?

I get clean data from both my SLs. One on a steel frame, the other on alu. Both mounted as per instructions on seat stay and using the thin rubber strip supplied. Lucky I guess. I did get drops from standard hub in my fixed gear wheel but they've gone since I "locktited" the torx bolts under the batteries so they don't come loose. Nice clean data there too. Nice to know about the other options should problems arise.

 

[zaskar]

I get clean data from both my SLs. One on a steel frame, the other on alu. Both mounted as per instructions on seat stay and using the thin rubber strip supplied. Lucky I guess. I did get drops from standard hub in my fixed gear wheel but they've gone since I "locktited" the torx bolts under the batteries so they don't come loose. Nice clean data there too. Nice to know about the other options should problems arise.

Thank's i only been using PT since Jan. i notice that all my 20-60 min intervals are all clean no breaks. it occurred to me, i think the breaks are when i have to stop at traffic lights.