Hollowtech NDS Bung

[Chislenko]

Just out of interest and to see if other people's experiences tally with mine, how tight do people generally do up the plastic bung?

 

[Cycleops]

There's a special wheel often attached to the bearing tool or can come on its own.

 

[Chislenko]

There's a special wheel often attached to the bearing tool or can come on its own.

Yes, I have the wheel as I do a complete strip down of the bikes every year for a proper clean.

 

[richardfm]

This the "special wheel" https://www.condorcycles.com/products/shimano-crank-installation-tool-for-hollowtech-ii

Just use that to do it finger tight

 

[C R]

Just out of interest and to see if other people's experiences tally with mine, how tight do people generally do up the plastic bung?

I think the shimano manuals specify a very low torque, something like 1 or 2 Nm, so not tight at all. The purpose of the plastic nut is to hold the crank arm in the correct location for the locking tab to catch the spindle before tightening the pinch bolts. Once the pinch bolts are tight the plastic nut doesn't serve any purpose.

 

[ianrauk]

You just have to nip it up.

 

[cyberknight]

as mentioned above it a tool to tighten the arm enough to eliminate play in the crank arm, it only needs enough to stop wiggle .

 

[Chislenko]

Yes, in agreement with above posters, I usually do just a couple of turns until I feel a bit of resistance. I was just curious as to other people's methods but we all appear to be "singing from the same hymn sheet" quite a rarity on here🙂

 

[Yellow Saddle]

The purpose of this nut is to put the required axial preload on the bearing. By definition, this will also remove sideways play in the crank. A BB bearing has to support the crank in two directions - perpendicular to the axle and along the axis and without preload the bearing will fail quickly. How quickly? Compare the life of a Shimano Hollowtech BB to that of BB30. Over the average of bikes with serviced in a bike shop, the Shimano set-up lasts about three times longer than BB30.

Now, I'm sure some of you have an aunt Edna who's BB30 bike has done 300 000 kms without any problems, including our American friend here, but as I said, on average as calculated in a bike shop.