Bicycle Mechanics - Dura-ace front hub - missing bearing
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I was just servicing the front hub of my dura-ace 7801 wheelset and noticed that there are 16 loose bearings on each side with a gap. This means there is room for one more bearing on each side.
Can I just add another bearing or does the design only call for 16 bearings leaving this gap.
I may be mistaken, but I think there is supposed to be a gap for movement.
I believe you have just found the "n-1" rule of bearings. (n-2 for headsets I believe)
that is to say as many bearings as will fit or start to jumble and remove one. a search will probably tell you more, but for your purposes, the hub likely has the right number of bearings. :)
WH-7801 callout (http://techdocs.shimano.com/media/techdocs/content/cycle/EV/actionsports/WH/EV-WH-7801-F-2515_v1_m56577569830608637.pdf) is for a retainer with 5/32" balls. I take it someone replaced it?
(Yes, use the n-1 rule if no retainer.)
08-27-07, 12:20 PM
There definitely should be extra room in there, just not a lot. 16 seems like a weird number to me, though. I thought bearing numbers went in 9s, 10s, or 11s?
HB-7800 hub takes 14 per side (loose). One I know takes 18. Kinda depends on ball size.
08-27-07, 03:35 PM
" Can I just add another bearing....."
You don't want to add 1 even if it needs it. Replace all of them from the same lot, so they match up.
IF 1 is a slightly different size, bad (grindy) things can happen.
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