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royce hubs

Posted: 27 Jun 2013, 3:37pm
by mig
does anyone use one?

opinions please!

Re: royce hubs

Posted: 27 Jun 2013, 6:50pm
by Elizabethsdad
I went to Royce Engineering today about getting some work done and Cliff is very knowledgable and passionate chap about all things cycling. There might be better hubs out there but I don't think you would going wrong to get your hubs from Royce.

Re: royce hubs

Posted: 27 Jun 2013, 8:57pm
by mig
i'm advised that they work best with a 75% airspace vs 25% grease in the hub. why would that be?

Re: royce hubs

Posted: 28 Jun 2013, 1:00pm
by Brucey
some (many) bearings are specced as being ~1/3 to ~1/2 grease /total housing volume, e.g.

http://connect.timken.com/packing-tapered-roller-bearing-with-grease

There are two reasons for this in (relatively, vs bicycle hubs) high speed applications;

1) the excess grease comes out.

2) the bearing can overheat.

In a car wheel bearing both are possible, and when the grease comes out, it can find its way onto the brake discs with predictable consequences. Roller bearings work the grease harder than ball bearings, and generate more heat when overpacked by some margin. For really high speed running, wheel bearings should be oil lubricated. Famously this was proven (the hard way) when Art Arfons' wheel bearing on his 'Green Monster' land speed record car failed at ~600mph. The bearing overheated, seized, then sheared the stub axle off, all in about three seconds. It could be that a witness to this prang originated the 'rolled up into a little ball' description of the results. Mr Arfons was lucky to survive.

Overpacking a bicycle wheel bearing may result in a little extra friction, maybe some lubricant loss, but isn't likely to be harmful otherwise in the same way; speeds are just not high enough for that. Obviously using a thixotropic semi-fluid grease gives oil-like levels of friction and seal lip wetting in use, but without the same risk of static leakage past less-than-perfect seals when the bike is stored.

cheers