Buddy2003

Hi,

A bit of a dorky question, but here goes.

I just replaced the bearings on my elderly Shimano 600 (aka ultegra) front wheel hub (takes 3/16" ball bearings).

How many bearings should it normally take? I read that most front hubs take ten 3/16" bearings. There were 10 bearings fitted, but I noticed that there was a ball-bearing sized gap i.e. there was room for an 11th bearing. Figuring that maybe the last person that renewed them had screwed up, I replaced the ten old bearings with 11 new ones (now no gap). The hub appears to work fine - is the gap required to allow proper bearing operation i.e. should I dismantle again and remove the extra bearing?

fish0n

I believe the gap is supposed to be there.

vpiuva

There should be space. If there was none left after you put that 11th one in there, you've got too many and it will result in premature bearing and cone wear. N-1 is the rule on hubs.

Buddy2003

Okay,

I just did the rear hub and there were 9 bearings (as I had read elsewhere) with no gap??

Any thoughts??

JanMM

The general rule for hubs with loose ball bearings is n-1. If the races and cones were in good shape on this older hub, tho, I would consider putting it back together as you found it, only clean and with new grease and ball bearings.

Buddy2003

Guys,

Thanks for the advice.

FYI, I downloaded a front and rear hub manual from Shimano for Ultegra hubs. This specified 11 x 3/16" BB for front and 9 x 1/4" BB for rear (per side) i.e. as I believe that 600 and ultegra were the same, it looks as if there should be no gap(?), although I hear what you are saying.

well biked

What I do is put bearing balls in until they jumble up, meaning the last one isn't sitting in the cup properly because there's not room, then remove one. This sounds like what you've done. My understanding is that this is n-1, with "n" being the number of balls it takes to begin jumbling. It will vary how much of a gap there is when you remove the one ball after jumbling, sometimes it's very small, sometimes it's nearly wide enough for another ball. The only place I do it differently is with headsets, I do n-2 there. Headsets with n-1 tend to not work smoothly-

Buddy2003

Thanks, the n-1 term is a bit confusing. The way I installed the BB's was so that they were all comfortably seated with no room for another bearing which is what you are saying

HillRider

Yes, if there was no gap at all, you didn't have the bearings positioned in the right places in the race. You had them to close to the axle center line. It's not a problem as they will align properly when the cone is threaded in and adjusted.