Servicing a Headset

[Slick]

I have replaced cartridge bearings before and whilst they are easy I've usually found the most difficult part is identifying then sourcing the exact one you need. The good thing about them is it's easy to tell when they need replacing as there is a noticeable shake in the steering. My Genesis is showing slightly different symptoms more just a stiffness in the steering and what I assume is a tell tale sign of grease leaking and leaving a stain on the frame. Am I correct in assuming this suggests lose bearings and can I just dismantle in the usual manner and regrease? I don't want to take it apart only to realise I need to replace the bearings and can't use the bike tomorrow morning.

Thanks in advance.

 

[gbb]

Sounds exactly like a dry bearing. I had this on a former bike and when stripped down the bearing was exceedingly dry and stiff and you could see rust red stains. My first reaction was...new bearings required...but I simply removed the bearings, cleaned, dried, regreased......and that bike ran like that, flawlessly for at least a couple years until I sold it.
Don't assume new bearings are required.

 

[Slick]

Sounds exactly like a dry bearing. I had this on a former bike and when stripped down the bearing was exceedingly dry and stiff and you could see rust red stains. My first reaction was...new bearings required...but I simply removed the bearings, cleaned, dried, regreased......and that bike ran like that, flawlessly for at least a couple years until I sold it.
Don't assume new bearings are required.

Your spot on. I opened it up and was surprised to see a cartridge on top but when I dropped the forks I could see the bottom bearings were lose and dry as a bone probably seized. Do I just remove the lose bearings and regrease without touching the race they are set in?

 

[Slick]

Looks like a trip to LBS as the bottom bearings were not seized they were held in place by a rubber band with holes for individual bearings. I've never seen that before but no surprise really as all I've dealt with is the cartridge.

As an aside, the top cartridge bearing feels lije it's in tip top condition. Are they more efficient or just not working as hard?

 

[rogerzilla]

The top bearing doesn't take much load compared to the bottom one. If there is any play in the headset, the top race takes no axial load.

 

[Smokin Joe]

Looks like a trip to LBS as the bottom bearings were not seized they were held in place by a rubber band with holes for individual bearings. I've never seen that before but no surprise really as all I've dealt with is the cartridge.

As an aside, the top cartridge bearing feels lije it's in tip top condition. Are they more efficient or just not working as hard?

The top bearing has very little weight on it so they do suffer minimal wear.

 

[Slick]

Eh, turns out they were both cartridge bearings just the bottom bearing had actually disintegrated and is still stuck in the frame.

 

[Yellow Saddle]

Both bearings take exactly the same amount of weight as they share the load.

The reason the bottom bearing rusted is because the front wheel sprays water into it. The top bearing is protected.

The reason a bottom bearing needs replacement sooner than a top bearing (other than for rust reasons) is because it suffers from fretting. Your weight and road irregularities make the fork flex at the bottom bearing race. This flexing temporarily jambs the bearing balls between the two races and prevents them from rolling properly. They then experience a fretting (filing) movement.

Further, a headset bearing doesn't rotate fully like a wheel or crank bearing. It just oscillates in place, as you ride. That squeezes the grease out from between the three friction surfaces and make the bearing run dry. Combine this with fretting and you get bearing failure.

Although rust isn't the absolute death-knell for a bearing, if it has rusted, it will be rough. It all depends on how well you clean it and what level of roughness you want to put up with. As headset bearings become rough, they become more difficult to adjust and sometimes it is impossible to tune them to that fine margin between binding and knocking.

That elastic band you saw in there is a nylon cage. It keeps the bearings separated and makes them easier to replace and pack.

 

[Slick]

Both bearings take exactly the same amount of weight as they share the load.

The reason the bottom bearing rusted is because the front wheel sprays water into it. The top bearing is protected.

The reason a bottom bearing needs replacement sooner than a top bearing (other than for rust reasons) is because it suffers from fretting. Your weight and road irregularities make the fork flex at the bottom bearing race. This flexing temporarily jambs the bearing balls between the two races and prevents them from rolling properly. They then experience a fretting (filing) movement.

Further, a headset bearing doesn't rotate fully like a wheel or crank bearing. It just oscillates in place, as you ride. That squeezes the grease out from between the three friction surfaces and make the bearing run dry. Combine this with fretting and you get bearing failure.

Although rust isn't the absolute death-knell for a bearing, if it has rusted, it will be rough. It all depends on how well you clean it and what level of roughness you want to put up with. As headset bearings become rough, they become more difficult to adjust and sometimes it is impossible to tune them to that fine margin between binding and knocking.

That elastic band you saw in there is a nylon cage. It keeps the bearings separated and makes them easier to replace and pack.

Looks like I may have bitten off more than I can chew with this.

To get the bearing out that was stuck in the frame I had to knock out the entire cup but I assume that will go back to its natural position under compression when I fit the fork.

Looking at the fork, I'm no longer sure what's fork and what's remains of the bearing or even stuck retaining ring.

I'll post pictures as I think it's the latter as the fork won't sit anywhere near as flush as it should.

 

[Slick]

Looks like fork but I'm starting to think it's remains of the bearing.

 

[Slick]

Showing the way I'm trying to fit the bearing

 

[Slick]

The huge gap.

Looking at the pictures it looks obviously the remains of some other part but when I look at the bike it looks like part of the bike.

 

[Yellow Saddle]

Looks to me like the inner race of the bearing is still stuck in there.

 

[BianchiVirgin]

There is clearly a piece of the old race there. Need to get it off first.

 

[Smokin Joe]

Both bearings take exactly the same amount of weight as they share the load.


.

Surely you've got the weight of the frame and more of the riders weight on the top bearing?