Old School Wired Powertap Rebuild And Wheel Build On A Tuesday Night.


Well-Known Member
Feb 5, 2010
A few weeks back my secondhand PowerTap wheel died on a ride. It went severly out of true due to a spoke nipple pulling through a crack in the rim. The wheel has been a bit rough since I bought it but has functioned reliably enough to avoid monkeying with it. The bearings in the hub have always been rough and the freehub body is severly gouged messing the alignment of some of the cassette sprockes, recently the engagement of the freehub has not been crisp either.

Looking at the new and used market for Powertap wheels, I decided to do a rebuild. I ordered the parts from Ebay:

Bearings ~ $10
Brass Wheelsmith Spoke Nipples ~ $10
Wheelsmith double butted spokes (32) ~ $20
H+ Son SL42 Rim ~ $75
PowerTap replacement freehub body ~ $50

The bearings and freehub arrived promptly and I got to work rebuilding the hub. I had to get creative in getting the old bearings out, but Google was my friend and I found some good HowTo's with a lot of pictures that helped me to avoid damaging anything. Once the bearings were out, I cleaned up everything, pressed the new bearings in with a 17mm socket and rubber mallet, greased the vital bits and installed the new freehub. The hub now feels, sounds and looks like new.

I had to wait on the wheel build until tonight. The nipples were the last item to arrive - and I was itching to twist 'em. In the span of 3 hours, I laced the wheel 2x on each side, tensioned, true, stress relieved and retrued the wheel until I was satisfied. I followed the directions on the Sheldon Brown website and the spoke lenghts were calculated using the ProWheelBuilder calculator. Tension on the drive side is as high as I dared to go and I achived decent tension on the non-drive-side as well. Spoke to spoke tension variance is low as determined by their tone.

Here is the end result:

I have to wait for tomorrow to test ride and be sure that the hub still functions. I will report back.
"Once the bearings were out, I cleaned up everything, pressed the new bearings in with a 17mm socket and rubber mallet..."

Use the vice...er...vise! A 6" bench vise makes a good ersatz bearing press. As does using a long bolt or piece of all-thread with washers and nuts. And, of course, there's always that sweet Chicom Harbor Freight arbor press you've been meaning to add to your tool collection!

I actually had the rubber mallet out yesterday and used it on the from BB of that Santana tandem's eccentric mount. The two set screws used to secure the eccentric's adjustment position after tensioning the primary drive chain raises burrs on the aluminum eccentric...which make the eccentric tough to rotate with a face pin spanner. Brute non-marring force to the rescue! Drove it sideways in both directions enough to expose the burrs and dress them off without having to remove the crank arms.

Nice rim choice, Maydog. Aero, durable and good looking. I use the Park Tool spoke tensiometer as a reference check to keep tension even, but like you I've learned to use my ears over the years of wheelbuiding and get pretty darn close to perfection without the gauge.

I'll bet your power and weight bed those spokes and nipples in just a little bit more! Give us a riding report ASAP!
I did use the bench vise after the bearings were in to make sure they were seated, but the mallet did the job without being too violent.

The rim choice was a toss up between the SL42 and the H+Son Archetype which is lower profile but wider - maybe for my next build.
Depending on the application, I like to use a light ball pein hammer and listen and feel for a full contact seating.

One of these days I'll spring for that big dollar Park Tool bearing press, but for years I've had good enough results with my el cheapo Nashbar press, a few all-thread presses I've made up and the old stand-by set of sockets used as pressing arbors. I've only had my tensiometer for a few years and the one time it actually helped me was in re-setting the tension of my well used Aksiums to match one of the new sets I had laying around...just a direct comparison reading.

Not a damned thing wrong with keeping that PowerTap in service and WheelSmith spokes are every bit as good as DT and Sapim IMO. You should wind up with a great wheel.
I am comfortable with the tonal method of tensioning, I have built a few sets of wheels and repaired several others with good results.

Nowadays there are good free phone apps that can help. I played with using a guitar tuning and frequency spectrum app. In the end it just did it by ear.
Update: I put on a moderately hard 26 miles over lunch and I am quite pleased. The wheel rolls nicely and is very stiff. With a little assistance from the wind, I stole a 2015KOM and several PRs on Strava. I didn't lay a whole lot of power down until the end, where I wound it up to 1200 watts - the wheel took all of that power without any noticeable play.

I must have built it right, there were no clicks, pops or pings when riding and it is still dead true.

Me so happy.

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