Bicycle Mechanics - Dura-ace front hub - missing bearing
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
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, 11:20 AM
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, 02:35 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.
Powered by vBulletin® Version 4.1.12 Copyright © 2014 vBulletin Solutions, Inc. All rights reserved.