Caged headset bearings - what size?

rumbataz

I serviced my headset this week and found that the upper and lower bearings were caged headset bearings. I degreased all the components and greased the bearing races before reassembling everything.

However, I want to replace the bearings as they've been on the bike for 5 years now and it's a straightforward job, now that I've learned how to take apart the headset and reassemble it.

But what I'm confused about is the size of caged headset bearings that I will need as a replacement. What are the dimensions I need to measure on the existing bearings in order to find replacement ones?

cooldad

Just measure the size of the balls and buy a bunch of loose ones. The only reason they use cages is to make assembly quicker and cheaper. They just rust away in the end.

The Rookie

Caged systems reduce the number of expensive balls by using a cheap and shite cage, as CD says just fill it with loose balls, barely costs anymore and far superior.

rumbataz

I'm keen not to mess anything up as the bike runs very well at the moment. To determine the right size of ball bearings, do I just measure the size of one of them that's currently in the cage? What about an allowance for the cage itself? Plus, what would hold them in place on the bottom side of the fork?

I understand that on the top I would place then in the race, but not sure how I would install them on the bottom side.

The Rookie

Just measure the diameter, will be either 1/4" or 3/16", usually (like 95% of the time) the latter.

The cage has no effect on diameter, you just buy more.

You smear grease in the cup (which is needed for lubrication and to reduce water ingress anyway) and push the balls into that, it holds them in place during assembly.

avalanche_expert

I would take one of your cages with the bearings to good local bike shop and get them to supply you with a replacement set.

Avoid the big cycle shops as they tend to be useless with things like this. A local backstreet bike shop will be a better option than the big chains.

That's exactly what I did when sourcing new bearings for mine. I did eventually swap the headset to a sealed cartridge type. Personally I think the cage/loose bearings set up is crap on a MTB.

cooldad

Halfords sell caged bearings really cheap. But as pointed out the cages are pointless, and only used to make the assemblers life easier - so normally a slave in a Chinese factory or something.

rumbataz

I need to dismantle the headset again to see what's what.

I still can't figure out where I would physically place the bearings in lieu of using the cage. The top one seems easier as I just grease the race and then place the loose bearing in it.

However, the bottom one is where things confuse me. Currently, the bottom cage is simply place over the steerer tube and rests on top of the forks. So, I can't see how that could be replaced by loose bearings. There is no 'cup' as such to place them in.

keef66

rumbataz wrote:

I need to dismantle the headset again to see what's what.

I still can't figure out where I would physically place the bearings in lieu of using the cage. The top one seems easier as I just grease the race and then place the loose bearing in it.

However, the bottom one is where things confuse me. Currently, the bottom cage is simply place over the steerer tube and rests on top of the forks. So, I can't see how that could be replaced by loose bearings. There is no 'cup' as such to place them in.

The lower bearing race will be in the head tube but facing downwards.

If you turn the bike upside down you can grease the lower bearing race and pop in the loose bearings before inserting the fork which should then hold them in place. Flip the bike upright again and do the upper ones.

But if you're happier replacing like for like, take the old ones into Halfords and you'll likely find suitably sized caged bearings. Last ones I bought like that even included a tube of grease (which was bugger all use to me since I'm still using the pot I bought when I got my first car in 1981)

rumbataz

^ Nice one - that makes sense. I've got a bit of a tinkering bug at the moment and am happy to experiment on my hybrid as it was a cheap bike so if I mess it up I'm not too bothered.

I've got a digital vernier gauge so I can measure the cage.

Another thing that I need to be clear on: the cages had a 'flat' side. I presume the non-flat side should face the bearing race?

The Rookie

Vernier is for measuring the ball bearings not the cage!

The cage can only go in one way, get it wrong and the graunches on the races.

Top and bottom bearings are the same, you have a cup on the top and a cup on the bottom, bearings go in both the same!