What's the difference between un91 and un73?

[Woodsman]

I have acquired a couple of these NOS for two bikes I have. I've been using un73 up to now and get between 4 months and a year out of them (I ride a lot I guess). Anyway, apart from the weight which I assume to be a bit lighter, does anyone know if there is any other difference apart from the cost of course.

Just interested…….

 

[troje]

Cost and weight mainly, right? I haven't noticed any other difference and all of the UN5x, UN7x and Un9x series have last similarly long in my bikes.

 

[xerxes]

18.

 

[hamster]

I had understood that you can split up a UN91 and fit new bearings (an industrial bearing provider should be able to supply), unlike UN7x or 5x.

 

[Woz]

http://www.bikepro.com/products/bottom_ ... un51.shtml

 

[Woodsman]

Great and interesting responses so far, thanks and keep 'em coming.

I have to say the UN91 do feel nice (in hand) and have a different finish to them which adds to the perception, that they are of a higher quality….

I've a Royce on another bike, and the bearings are nothing special, but the whole unit is so precisely made that it feels sublime on the bike - like no other but at 180 quid a pop just couldn't go that route at the moment. Three summers of hard riding wore that unit out - Royce replaced it free of charge so hopefully I'll get another three out of it. It is very light too!

 

[ultrazenith]

That's interesting about the Royce unit. Is it standard company policy to replace worn out units?

 

[Woodsman]

No, Cliff said there was a fault which is why it went so quickly

 

[ultrazenith]

I see. How long are their products meant to last, typically?

 

[Woodsman]

I don't think you'll get that sort of info from them. When I removed it from the frame (for frame repairs) I noticed the bearing outer had been spinning inside one of the cups. Cliff had a term for it, so he insisted I send it back with the warranty card (lifetime on the Ti axle) - sent me a new one. If I get another three years from that I'll still be happy - hopefully more or just needing bearing replacement.