The reason you have to send your powertap in to replace the cartridge bearings is that they need to recalibrate the torque tube when that goes.

Good luck with the DIY replacements.

so are you saying that replacing the bearings will effect the accuracy of the PT?

so who services the hub outside of the USA then? surely not every wheel is sent back to the USA for simple bearing replacement....

does anyone have a way of checking the unit after a rebuild?

I sure hope not

Replacing the bearings *can* affect the calibration (accuracy) of the unit. To be sure, do a "stomp test" before and after the replacement and compare values. Cycleops' EU service centre can be found in the czech republic:

http://www.cycleops.eu/

Replacing bearings *can* affect the accurancy but generally it never does, at least in my case. I regularly service several powertaps of my friends, also mine (from Elite+ through SL+ to MTB Disc) and nobody of them never noticed any bad readings, dropouts or inacurrancy. Avg torque and power didn't change at all after replacing of bearings. BTW replacement of them and calibrating costs about 100euro in Trueconnextion and they usually put EZO bearings(one pcs is around 3-4euro). I think that all the 'story' with calibration and lack of accurancy is for those who have too much money, at least 2 powermeters and can afford not to train with power for a week of two.

I recently bought a Powertap SL. It's wireless, which is cool, but I found out that it's the "old version" Powertap 2.4 SL hub. I'll do the ANT+ update to make it an "SL+" but it will still of course be the 12mm axle, vs. the newer 15mm axle.

I can see from this great thread that the 12mm version has slightly smaller bearings (6901 vs. the slightly larger 6902 bearings in the SL+), but is that more than a very minor issue?

I'd like to figure it out now before buying rim and spokes and building up the entire wheel.

I am in exactly the same boat as above!!!

The wheel is amazing (zipp 404 with sapim bladed spokes) but I am in the process of upgrading it to ANT+

the bearings are not "rough" but are pretty draggy compared to say the reynolds hub in the DV46UL I have as a comparison....

do people here have any info on how good the hub should spin?

I think I might have to do the rebuild myself.... about to get the enduro zero bearings!!!!

Having both an SL+ with 15 mm axle and an SL 2.4+ with 12 mm axle i personally wouldn't call it an issue at all. Neither from a riding nor from a maintenance standpoint.

Setting a pair of bearings into a solid hub has nothing to do with the torque tube or anything else?
It's just a plain old hub that needs to be treated carefully?
Saris are just trying to scare people from servicing their own hubs?
RE-calibration........resetting the original settings....blah, blah......
Whatever, if you fit the bearings carefully, you'll have no issues.
I've done more than 40 hubs now and never had any problems.
My only tip is......don't press fit the bearings, tap them in instead in your lap as it's much less stressfull for the tube in the centre.
Regards, Rob.

_________________
Guildford/Woking is the home of F1.
We make loads of other stuff here too.

that sounds promising then!!!!

good news....

any ideas how rough vs how free spinning it should be after new bearings? I am trying to judge if mine is worth doing sooner rather than later...

How did you determine that? Tapping in bearings seems more likely to cause stress, misalignment, etc.

One tip for easier bearing installation is to put them in the freezer for an hour before popping them in the hub.

Replacement bearings have just arrived, Enduro Zero Ceramic's....

Now to replace the old ones, anybody know of somebody reputable who I could take my wheel to in the UK, Manchester area would be great

Thanks

http://www.youtube.com/watch?v=fS_BL1b2wns

just found this thought id share it, show how simple a job it really is

From my local LBS Guy: "To keep you informed, I have the hub broken down and replacement bearings are on the way. I can imagine that Saris/Cyclops doesn’t want people taking this hub apart because they don’t want anyone seeing that their $1000 hub has a piece of electrical tape holding the magnet to the axle. Precision my foot! Your wheel should be ready to go Friday afternoon, I will send a message when it’s ready."
Thanks to all the posters who provided the information on repairing this hub. You saved me over $300.00!!!

For all you Powertap Pro Hub owners note the following, ignore at your cost!

Based upon the manufacturers sizing chart that comes with the Hub, the replacement bearing sizes are specifically listed as 6901. However, when the Hub was stripped down the installed bearings were of 6902 type.

So, i know have 4x Enduro Zero Grade 3 Ceramic 6901 Sealed Cartridge Bearings sat on the shelf gathering dust. Any takers

Cheers.