# Axle shield tool needed?



## lstocks (Apr 9, 2002)

I was getting ready to install a new crankset in a 2010 Madone frame, and Trek's instructions say to use their "installation tool" to get the two-piece plastic axle shield installed correctly. It says when installed correctly, the two halves go together with an audible click. This installation seems too easy without a tool--is this thing really needed? Thought I'd ask someone who's been down this road before


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## johntrek5 (Nov 8, 2010)

I have slipped them together without any special tool. They just slide into each other, and no big deal. Just make sure you torque correctly.


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## lstocks (Apr 9, 2002)

You mean torquing together the two halves of the crank axle? The Campy set-up I have states 42 Nm --it sounds like from what I see on the boards the cranks on Trek's have a tendency to work themselves loose?

Thanks!


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## johntrek5 (Nov 8, 2010)

I have only put one together with Ultegra with the internal bearings. Basically once you put the plastic sleeve together inside the bottom bracket, insert the bearings andseals, install crank side, then put the crank arm on. Torque from that side. Then torque the crank arm bolts. On the Ultegra it has two hex bolts. I do each one a little at a time. I have heard they can work themselves slightly loose over time. Might not be a bad idea to re torque after a few hundred miles.


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## zac (Aug 5, 2005)

lstocks said:


> I was getting ready to install a new crankset in a 2010 Madone frame, and Trek's instructions say to use their "installation tool" to get the two-piece plastic axle shield installed correctly. It says when installed correctly, the two halves go together with an audible click. This installation seems too easy without a tool--is this thing really needed? Thought I'd ask someone who's been down this road before


No, it is not needed. But the important thing here is to make sure the outer flanges of the shields are seated in the BB shell/socket recess for them, and yes they will make an audible click when they are seated correctly, as the fit is that precise. You should also do a visual inspection to make sure they are properly seated. Additionally, prior to installation, make sure both the flanges and the sockets are perfectly clean, as even a spec of sand will prevent proper seating. 

This very issue, I suspect, may have been a contributor to the "loose" bearing issue that has been reported by so many. If the flanges are not properly seated, they will prevent the bearings from seating properly. Over time this will cause problems as the bearing would be free to precess* in the socket. (*Not sure that is the correct term, but it works).

You can make your own tool if you are so inclined. It is nothing more than a threaded rod with appropriate sized spacers and washers that when inserted through the BB shell and tightened, "pull" first the shields into place, then later the bearings. (Very similar to a headset race setter, but on a smaller scale).

hth
zac


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## lstocks (Apr 9, 2002)

Thanks very much for your information..very helpful!


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