how to put bearings on hubs?

yeah, noob question :o
my bearings always get stuck on the little raised bit (blue)
is there some technique to getting the bearings on? :stuck_out_tongue:

mmkay, bobousse explained it to me, i’ll repost here
basically, the best way to do it is to put a piece of seatpost over the splines so that it is on the inner metal ring, then hit that with a hammer until it goes in :roll_eyes:

When I put mine on I just put the spacer and the crank on and I screwed my crank in it just pulled the bearing in.

Bearings and shafts are supposed to have what is called an “interference” fit. The diameter of the shaft is about 0.0001"-0.0005" larger than the ID of the inner race of the bearing. You should not be able to push it on by hand, it should get stuck. Both methods mentioned will work, the crank tightening method being the preferred one. Oversized spacers (too thick) should be used to insure that the bearing is pushed all of the way on until it engages the lip circled by the red ring in your photo. Then remove the crank and install spacers with the correct thickness.

To really do this correctly, the bearing should be pressed on with a sleeve (like the seat post section) using an arbor press or hydraulic press to drive it. Having the wheel built onto the hub makes that very difficult to do because one then needs a press that will accept that large of a work piece.

I used my old bearings and a rubber mallet to tap the new ones on. A section of seatpost sounds like a pretty good iea too!

I changed a couple of sets of bearings recently and the first set almost refused to come off. I used a piece of seatpost and hammered the new bearings on, and it took so much force it deformed the seatpost. Be careful that as you strike the hammer that the seatpost lines up with the inner bearing race, the steel bit rather than the rubber protective bit. You can put a bit of wood underneath the other end of the axle as you bash to prevent damaging whatever surface you are on.
After the bearings being such a struggle I was hesitant to change the bearings on my 36" but I went for it, and was pleasantly surprised that the bearings slipped off without a fight and the new ones settled on with much less bashing.
So if your bearings seem a bit tight don’t give up they probably just need a bit of extra elbow grease and carefully applied force.

I just tightened the crank with the plastic spacer for my mad4one hub. Make sure you are careful not to strip the threads in the hub as it doesn’t have enough bolt in it. It worked fine for me.

Hammering is a last resort as the sudden knocking force can screw up the bearings a bit, even with the more ideal idea of hitting the inner race with a seatpost. Hitting anything apart from the inner race is a total nono.

My suggestion is the same as some people here: spacer and crank and tightening it on carefully to push the bearing on.

And apply a fine layer of quality grease between all points of contact between any metal surfaces. It should help the bearing slide on a bit and if needing removal it won’t be seized.