I thought the only differences were a bit of carbon on the SL hub and the axle diameter (12mm on the Pro v 15mm on the SL). I had not heard anything about the bearings or flange, but that may be true as well.

I can't directly compare the two, but have a HED built Jet 60 on a Pro+, and it's been great so far. I chose the Pro+ for the cost savings over the SL+, as the weight difference was pretty minimal. The + series work great with the Garmin 705 if you plan on using that set-up. Good luck in your choice.

 

The Pro+ has a 12mm axle and does not have the carbon windows in the center of the hub shell. The SL+ has a 15mm axle and the carbon windows. There is no difference in bearing quality between the SL and Pro+ but the SL+ bearings are smaller to fit the larger axle. The OD of the bearings is the smae but the ID of the SL bearings is largere which means it has The flange heights and spacing is the same between the 2 models.

 

Okay... that is useful to know. So the real question comes to whether the larger axle, slight weight reduction and smaller bearings represent a $150 difference in cost... Hmmm.

 

Why does an SL have a larger axle than a Pro?? Is it a weight thing? Durability thing?

 

Why does an SL have a larger axle than a Pro?? Is it a weight thing? Durability thing?

I believe they weigh the same, it is suppose to make the wheel stiffer. The bearings on the larger axle will actually wear out faster because they are thinner section then the ones on the 12mm axle. The weight difference between the two hubs is from the hub shell, one has a solid shell and the other has machined windows with carbon.

 

Why does an SL have a larger axle than a Pro?? Is it a weight thing? Durability thing?

what i heard was that 'some people' felt a bit of flex in the smaller axel of the pro.

 

I believe they weigh the same, it is suppose to make the wheel stiffer. The bearings on the larger axle will actually wear out faster because they are thinner section then the ones on the 12mm axle. The weight difference between the two hubs is from the hub shell, one has a solid shell and the other has machined windows with carbon.

According to Saris's 2009 manual, the versions with the 12mm axle use four 6901 bearings. The Shimano versions with the 15mm axle use bearings with a larger OD as well as ID in freehub and DS hub. These will take a higher capacity and should last longer than the 12mm bearings. The Campy version uses smaller bearings in the freehub though, so this one probably won't last as long.

Model Hub Bearings Freehub Type Freehub Bearings

Elite+ and Pro+ or any PowerTap with 12mm Axle 2 x 6901 RS Both 2 x 6901 RS
(6901 2RS 318 12 x 24 x 6)

SL+ and SLC+ 6802RS, 6902RS Shimano 2 x 6902 RS
(6802 2RS 219 15 x 24 x 5)
(6902 2RS 434 15 x 28 x 7)

SL+ and SLC+ 6802RS, 6902RS Campagnolo 2 x 6802 RS
(6802 2RS 219 15 x 24 x 5)
(6902 2RS 434 15 x 28 x 7)

 

So the main bearings in the hub seem pretty straight forward to replace, but how about the freehub? Are these easy to tap out and to replace?

 

powertaps have to be sent in for bearing replacement since it involves recalibration. I have over 20k miles on mine with original bearings and they are still fine. Freehub can be user-serviced, replaced, etc.

 

powertaps have to be sent in for bearing replacement since it involves recalibration. I have over 20k miles on mine with original bearings and they are still fine. Freehub can be user-serviced, replaced, etc.

but why is that? In so far as I am aware, the bearings are not an integral part of the power measurement and merely function as bearing in all wheels do. Not trying to pick holes, I am just reluctant to send a wheel back to their Czech service centre over here in Europe for the sake of a couple of bearings.

 

so I got my answer, if the bearings are pressed in, there should be not problem, the issue that can arise is with shocking the electronics is a hammer and drift are used to fit new bearings

 

the issue that can arise is with shocking the electronics is a hammer and drift are used to fit new bearings

That would be a good technique if you want to ruin the brand new bearings you're trying to press in...

 

so I got my answer, if the bearings are pressed in, there should be not problem, the issue that can arise is with shocking the electronics is a hammer and drift are used to fit new bearings

Or take them out. But even if you don't have the hub bearing tools you should be able to figure something out with a QR, a socket set, and a short piece of PVC pipe.

BTW, IMO the PTs look like a pretty poor design. The external caps are basically loose. The only thing making it a solid structure is the QR pressure on the inner race of the outer bearings. There are spacers on the inside, but everything needs to be perfect to avoid preloading... and we all know how seldom perfection is achieved. Based on others experience, the NDS bearing often has a short life because it is only a 6802 (the rest are 6902) and it has a lower load capacity.

 

All 2010 PRO+ have 15mm axles. The only real difference with the SL and SLC are the weights.