Last night on the trainer, I saw speed and cadence show up on my garmin 500, so I put my head down, and started spinning. 7 or 8 minutes later, I looked down, and saw cadence, but no speed. I looked at my wheel magnet, and sure enough, the magnet was no longer aligned with the sensor. In fact, it was almost to the carbon on the 808 (aluminum rim clincher). I figured easy spinning was fin, but the centrifugal force of riding faster pushed the magnet to the outside.
The problem lies here: The spokes are bladed, and I can’t tighten the magnet enough to grab onto the spoke. So I did a quick fix to get me through the next 45 minutes, which was to cut a roughly 1 cm long piece from a nearby ziptie, and squeeze that between the magnet and spoke to make it tighter. It got me through, but still moved about another cm towards the rim during the rest of the ride.
Any suggestions on more permanent (barring glue) fixes? Im thinking electrical tape around the spoke, but we don’t have any right now.
FWIW I did pretty much the whole ride at 17-20 mph, so not sprinting by any means.
My training wheels have bladed spokes (Mavic Ksyrium). Had them for 8 years now and I’ve never seen that problem. I use the Garmin magnet, and before Garmin I used about three different bike computers. Also no problems. The spokes are bare metal. Maybe yours are treated or painted and that’s the difference?
Edit: how could I forget? I have SRAM 60 and 80. They are basically old Zipp design like yours. Black blades spokes. Also no problems with Garmin magnet.
Anyway here’s an obvious solution. Get the new Garmin separate speed and cadence sensors with accelerometers instead of magnets. No magnets no more problems.
Had this issue on my 404. I switched out the Garmin magnet with a Mavic magnet from a pair of Crossmax wheels. It can be screwed down tight and never budged again. See link.
This is hardly a Zipp 808 problem, it’s a spoke magnet installation problem.
I too have used a Garmin magnet on a painted, bladed spoke and it works fine - it wasn’t a Zipp
There’s three things you can do to fix this and I suspect you’re approaching it wrong.
You can use more force, get better grip with less force or use a secondary restraint outboard of the magnet.
Is the magnet holder actually closing enough to tighten on the spoke (regardless of whether it slides)?
You can keep increasing clamping force and eventually it may hold but it’s a much better solution to improve the grip without excessive force.
If the surface of the spokes and/or magnet housing is contaminated with a lubricant of some sort you’ll get poor grip. If that’s the issue all you have to do is clean the spoke and the magnet housing and see if that sorts the problem. Some soapy water and/or an alcohol wipe should do the trick. If that doesn’t work you could try wrapping a layer of electrical tape around the spoke outboard of the magnet so it can’t slide outboard. Alternatively you could put a tiny strip of double sided tape between the clamp and spoke, one side only should be sufficient, but I don’t think this should be necessary if the surfaces are clean and the tape may not help much if they’re not.
This really does seem like a pretty trivial issue and it’s certainly not Zipp’s fault unless they’re putting a non-stick treatment on their spokes!
Magnets that I have for my wheels has one round cut and on the opposite side of it a flat cut so I can install either on a round or flat spoke. Never had any sort of issues on my wheels…
Why base your trainer sesssions on speed? … If I would like to give you some advice go only fot time and Power and if you dont have power use HR insteed of speed…
Why base your trainer sesssions on speed? … If I would like to give you some advice go only fot time and Power and if you dont have power use HR insteed of speed…
Speed is fine as long as you’re not assuming it represents the same speed on the road. If your setup is very consistent speed can be useful in the absence of a power meter, especially for short intervals where HR lags too much. For a long consistent effort of minutes or hours HR is more useful.
Dilbert- The spokes on mine are bare metal. And I do like the look of the new sensors. Probably going to make that switch soon.
DeanV- Sorry about that. Fixed per your request.
jpwiki- But it looks pretty
Ai_1- When I tighten down, it gets tighter for a few moments, and then all of the sudden it is like I have gone past a limit of some sort, and it pops back to loose. I can spin it around and around and get nowhere. I’ll try cleaning the spoke and see if that does it.
Elitist Jerk- Should have seen that coming. Actually I did call my ride “W=fd.” I don’t know if anyone got it.
Jimster- Same here. I was sing the flat side and no bueno. Tried round side. No bueno.
johan2kona- No PM. I have a heart rate monitor somewhere… I don’t really structure my bike workouts during the winter so I was just pointing out what the garmin was saying. If I want it to be structured at all I just go by cadence because I pretty much have it in one gear from when it goes on the trainer to off. Good advice though.
…Ai_1- When I tighten down, it gets tighter for a few moments, and then all of the sudden it is like I have gone past a limit of some sort, and it pops back to loose. I can spin it around and around and get nowhere. I’ll try cleaning the spoke and see if that does it…
The standard Garmin magnet is just a piece of plastic holding a magnet that you clamp to the spoke using a thumbscrew threaded into the plastic. You’ve obviously over-tightened it and damaged the thread so that it skips back a thread every revolution when you keep turning. This will also limit your max compression, probably a bit more every time you do it. You may have wrecked it and need a new one. Don’t tighten it so much that “it pops back to loose” and you will avoid further damage. Try cleaning the spoke and if there’s enough thread left you might still get away with it.
With all due respect, it’s pretty amazing to start a thread which appears to blame Zipp for problems attaching magnets when in reality the problem is so simple as an inability to realise you’ve stripped a screw thread. It sounds like it’s entirely user error and has nothing whatsoever to do with the wheel manufacturer!
… FWIW I did pretty much the whole ride at 17-20 mph, so not sprinting by any means.
0 MPH. You were riding at 0 MPH…
but you go faster riding aero wheels.
The air from the fan isn’t interrupted nearly as badly - except that apparently we cool better with the fan blowing from the side, in that case he might tip over. (do I need this in pink?)
I second Dilbert’s suggestion of the new magnet-less sensors. They are easy to install, remove, swap between bikes ect. Additionally the speed sensor sits in a place where it can not get accidentally knocked/twisted out of alignment which can easily done on many other speed sensors depending on their configuration.
Dab a little bit of tubular glue on the spoke before tightening down the magnet, and it won’t slip after the glue has cured. You can peel it off and move the magnet later if you need to - the glue isn’t permanent. I’ve done this successfully on several wheels, and it holds well.
…Ai_1- When I tighten down, it gets tighter for a few moments, and then all of the sudden it is like I have gone past a limit of some sort, and it pops back to loose. I can spin it around and around and get nowhere. I’ll try cleaning the spoke and see if that does it…
The standard Garmin magnet is just a piece of plastic holding a magnet that you clamp to the spoke using a thumbscrew threaded into the plastic. You’ve obviously over-tightened it and damaged the thread so that it skips back a thread every revolution when you keep turning. This will also limit your max compression, probably a bit more every time you do it. You may have wrecked it and need a new one. Don’t tighten it so much that “it pops back to loose” and you will avoid further damage. Try cleaning the spoke and if there’s enough thread left you might still get away with it.
With all due respect, it’s pretty amazing to start a thread which appears to blame Zipp for problems attaching magnets when in reality the problem is so simple as an inability to realise you’ve stripped a screw thread. It sounds like it’s entirely user error and has nothing whatsoever to do with the wheel manufacturer!
Not that it makes much difference in the grand scheme of things, but it is a Cateye magnet. And I know, I didn’t mention this, so you can’t be blamed for calling it a Garmin magnet. Perfectly sound assumption.
In regards to the rest of your post…
The reason I have over tightened it, assuming that is correct, is because it never got tight enough. If it slips, then I am going to tighten it down more. If it slips again, yep. You guessed it.
That being said, if you are right, then I will try the tubular glue suggested, and if that fails, off to a new magnet (or new style sensors) I go. I was also not looking entirely to blame Zipp. I was rushed and see how it came out that way. The main problem that I (thought I) had was the bladed spokes on my Zipp wheel, so I put Zipp in the title. Sorry if I upset you. I was looking for suggestions, and I got them, so I am done here
I have a stack of little circular magnets, I prefer the low profile of the raw magnet rather than the plastic encased units. I just superglue them to the spoke, just a dot of glue is enough. It comes off easily.
