You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Random musings whilst having lunch, why do headset bearings last so long? Even on cheap headsets. Put some cheap bearings in your hubs and you’ll probably regret it a month later and they are working as they should, spinning 360 degrees constantly. Pivot bearings go notchy due to not doing full rotations.
Headsets seem to get lots of load, up from the wheel, down from the rider, doesn’t fully rotate but go for ages,
Any ideas why?
I guess because they don't really do a whole lot of work - most headset bearings will never turn a full revolution in their life so all they really need to deal with is static load, straight up through their axis (they are angular-contact so designed to do this). In my experience, it tends to be corrosion that kills them (or over-tightened top-cap!), particularly lower bearings which are more exposed to the crap. Uppers seem to last forever if well sealed, unless the bike has been used on a turbo without the headset being covered with a towel in which case....NGGGGGG!
That said, they don't last forever, but we are perhaps more willing to ride with subtly notchy headset bearings, where a rough wheel bearing is that much more obvious. Also, if a wheel bearing starts to show play (and especially a freehub bearing), it'll be obvious almost immediately.
Pivot bearings are odd things, but they generally seem to die because they either corrode or because they've run dry due to a lack of lubricant (which is very easily washed out). Linkages with lubrication points (e.g. SC VPP lowers), if kept pumped full of grease, do seem to last almost forever. Certainly, on my own bikes I reckon one set of greased lower bearings will outlast 3 or 4 sets of upper "sealed" bearings. Some linkages also seem to apply tortional forces through their linkage, which just tears the bearings apart leaving them sloppy. Others are much better at this (Whyte seem to have this nailed) and, combined with well-sealed bearing locations, means they last for ages and ages without maintenance.