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  1. #1
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    Powertap G3 servicing

    So in a previous thread I posted about G3 freehub problems. While my powertap is down I figured I'd swap bearings and try to get new seals.

    I was wondering what people use to lube the freehub pawls? (concerned about durability, not racing and saving a half watt)

    I was also wondering if there are seal or o-ring kits for powertap hubs? I emailed powertap about the dust and waterseal for the freehub, but haven't heard back.

    Last question. I noticed the magnet on the axle has vinyl tape around it. I hope that is not holding it in. It seems that the tape on mine is starting to peel and I was wondering if I should glue it down, tape over it or replace it?

    Bearing removal Advice and Lessons learned:


    I only found this in one other forum and it saved me. For the G3 You need to push the DS hub bearing out first and remove the axle form the DS. The magnet may not fit through the smaller NDS hole. Then to remove the NDS bearing the actual opening is a hex shape. So I ground down a bolt head to fit, then used the nut and some pieces from my automotive bearing kit to pull the bearing. washers and larger PVC pipe would probably work too. My "C-Clamp" style automotive bearing puller had trouble fitting though the spokes but got the DS bearing started out.

    On the Freehub, there is (was in my case) a set screw holding the inner bearing in. I wasn't paying attention and snapped it off. I doubt this will be a problem since the bearings are press fit anyway, but my freehub is damaged anyway. The bearings pushed back in with ease too.

    For bearing sizes I had (3x) 61902 abec 5 enduro bearings (2 in the freehub, 1 in the DS of the hub) and (1x) 61802 abec 5 enduro bearing (NDS hub).

  2. #2
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    The advice about punching out bearings in a proper order is correct. There is a magnet on the axle which is part of the speed sensor system (and provides angular velocity for the power calculations).
    A skilled mechanic can certainly replace these bearings, but you will risk altering the hub's calibration. You can manually zero a power meter with a head unit. Hub calibrations have to be performed at our factory in Madison, WI or one of our international service centers.

    https://www.powertap.com/post/blog-1...ap-hub-service

    Our bearing service includes a new freehub and calibration.

  3. #3
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    Brian,

    I plan on comparing ride data from previous rides to see if I am getting numbers close to where I was at before my service. (Edit) Now I have to apologize for being a little snarky, I really thought you were suggesting I spend $350 for a new freehub, bearings and calibration. The link you included only mentioned a freehub in the $350 option, This led me to believe your shop rate was around $175 and hour, and I was considering quitting nursing school. This link shows a new freehub, bearings and calibration with the $150 option https://www.powertap.com/service/hubs." The service that includes a freehub is $350, same as the price I paid for the entire hub (I built the wheel for like $425 with an R460 rim). Even if I bought bearings for $10 a piece and a $100 power tap freehub (that has 2 new bearings in it) calibration ($100) only would put me at $220 total. Since your freehubs don't have a bite guard I'm getting a novatec freehub for $55ish. So with bearings I'll be at $75ish and $175ish if I need to get it cal'd. So with bearings I'll be at $75ish and $175ish if I need to get it cal'd. Then I'll have $175 in savings to spend on beer. It also doesn't make sense to put on another aluminum freehub without a bite guard type system. If my calibration seems off, then I'll consider the $100 calibration service. (Edit)Then I'd actually be loosing money at around $175.

    It sure would be nice if you would point me to where I could get the dust and water seal for the free hub or respond with the spec for the freehub lube. Maybe even comment on the tape over the magnet.

    Overall, I'm happy with my G3 and appreciate the simple design, but I am not a fan of aluminum shimano splines on a freehub. If I was going to pay $100 for a freehub I'd expect there to be some kind of bite guard or maybe made of titanium for like $125ish. Really, I don't understand why the shimano splined hub is double the price of the campy splined freehub. If I had a CNC I'd just make my own freehub body.

    I'm confident that I will be able to change the bearings on my own, I used to break way more expensive airplane parts for the government all the time.

    Travis
    Last edited by traverpen; 01-20-2018 at 07:50 AM.

  4. #4
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    sent a pm for help.
    use a torque wrench

  5. #5
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    Hi guys, I had to replace the bearings on my G3 hub just recently. Thank you for the advice in this thread. I made a video in case it helps anyone else doing this job. My original plan was to record removal AND re-installation but my camera man (my son) lost patience with me and left me stranded. I apologize for the poor quality of the video and I hope it helps.

    Reinstallation just means using the same methods as for removal. The only discovery I made (after several failed attempts) is that when pressing the drive side bearing back in you cannot put anything right up against the axle on the other side to exert pressure in the opposite direction. You must put a cup over the non drive side so that the pressure is exerted against the hub flange not the other end of the axle. Just ping me if you have any questions.

    One more note, I used a threaded 10-24 rod from Home Depot for the job. Honestly, something a little bit thicker but still smaller than the axle ID would have worked better.

    https://youtu.be/FVjPtllX4Dg


  6. #6
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    So I got it all back together with the Novatec freehub. I noticed that both the freehubs had very close dimensions but the Novatec produced a bit of lateral play. The solution to this is to push the bearings out of both freehubs and swap the spacers in the freehubs. The PT spacer is slightly wider than the Novatec spacer.

    One thing I also noticed was that the axle had a bit of play after the bearings were in, and without the freehub and endcaps on. This tiny bit of play disappeared when they were installed.

    The long term question with the Novatec hub is with the pawls and freehub body durability. The PT has 3 (or 6 if you bought the expensive one). The PT hub appears to have 27 teeth. The Novatec freehub has 4 pawls. I am guessing that the PT freehub engaged all three pawls at the same time or 3 of 6 in the case of the expensive freehub. I am also guessing that the Novatec freehub will only be engaging one pawl at a time. In the past, on a different hub, I have mashed the pawls out of the body of a lightweight aluminium freehub, though this was on a CX bike, off road, crossing obstacles and waterbars where I was doing alot of hard 1/4 pedal strokes. I have a feeling that over time I may mash the pawls out of this freehub. The symptom of this, if anyone is wondering is when you start to coast, your RD gets yanked forward as the hub catches on the mashed out aluminium and the freehub becomes momentarily fixed, pulls chain forward and shortens the length of chain between the bottom of the crank and RD. Fortunately I noticed this before it became a catistophic failure and serious accident. The aluminium is softer than steel so it was quickly ripping off the piece of the freehub that was catching. I still have that wheel and I am kinder to it now.

    Now, I'm going to check the cal on the G# and report back.

    Travis

  7. #7
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    So for a static torque check I hung my bike up in my garage, used a strap to secure the wheel and a chain to hang weights on some MTB sprockets on my hub. I used 20lbs, 50lbs and combined the for 70lbs. I put each on the 36t and 28t sprocket. I used my head unit in calibration mode to read the torque. The results were as follows, everything besides the weight in lbs (20,50,70) and the tooth counts (28 and 36) are in Nm.
    Powertap G3 servicing-torquetest.png
    I would guess that the actual torque in most situations is much greater, like when a rider (weighting 150-190lbs) is standing on the pedals with mechanical advantage on that hub. So I hope the trend of decreasing percent difference with increasing weight is one that would continue. I don't have a lot of known mass items around my house, and the kettle bells handles made this easy. The next step is to ride some hills and compare the results in strava with past rides. Slower speeds on hills will make wind less of a factor.

  8. #8
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    Quote Originally Posted by traverpen View Post
    The long term question with the Novatec hub is with the pawls and freehub body durability. The PT has 3 (or 6 if you bought the expensive one). The PT hub appears to have 27 teeth. The Novatec freehub has 4 pawls. I am guessing that the PT freehub engaged all three pawls at the same time or 3 of 6 in the case of the expensive freehub. I am also guessing that the Novatec freehub will only be engaging one pawl at a time.
    Can anyone verify if this is true and will cause an issue? I also used a Novatec freehub to replace the PowerTap one since the PowerTap one is extremely expensive and doesn't last very long.

  9. #9
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    Well, I'm sure it doesn't have 24, 30 or 36 teeth. I'll post pictures when I take it off to inspect it on Friday. Along with pictures of damaged freehubs.

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