tight bottom bracket

Discuss light weight issues concerning road bikes & parts.
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mlc
Posts: 7
Joined: Sat Feb 19, 2005 12:04 am

by mlc

Have just fitted a new stronglight twister ISIS bb to my time vxr. On torquing up to required setting the axle rotation beocmes very stiff. Is this normal, will it free up with some mileage, or should I just back off the stated torque settings of 40NM?

bobalou
Posts: 1013
Joined: Mon Dec 15, 2003 6:05 am

by bobalou

mlc wrote:Have just fitted a new stronglight twister ISIS bb to my time vxr. On torquing up to required setting the axle rotation beocmes very stiff. Is this normal, will it free up with some mileage, or should I just back off the stated torque settings of 40NM?


The cups should go in by hand for at least a few turns. Inspect the treads of both the cups and the BB shell. I assume these are all brand new? If so then make sure the cups are greased before installing. I don't know about the stronglite ISIS BB, but the ISIS BB's Ive installed have a lip on both cups. Both cups on both sides should tighten all the way with the lip up against the shell. If not I'd be cautious .. not worth stripping any threads!

Depending on the BB, I don't always use grease. Sometimes 1 or 2 layers (or more) of teflon tape, depending on the BB and shell, but that's just me. Nowadays I find lots of cups come from the factory with some teflon imbedded in the cup threads so it can be redundant. If I use teflon tape then I don't use grease but just make sure it's VERY clean first.

BTW, I'm not a mechanic but just done my own wrenching for a long time. You might get some different advice here .. but I just told you what I do. :) Hope it works out.

by Weenie


mises
Posts: 1769
Joined: Tue Dec 23, 2003 9:28 pm
Location: Unknown parameter

by mises

Are you sure it's 40 Nm on both sides? A couple other brands I have used are something like 40 on the drive side and 20 on the non-drive and if you go to high on the non-drive it does the same thing you describe.

mlc
Posts: 7
Joined: Sat Feb 19, 2005 12:04 am

by mlc

misers - at 20NM on the non drive side the tightness seems manageable with no lateral movement. Think I will stick with this and give it a spin and see if things feel O.K.

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