52100 vs 440c sealed bearings

[buck91]

Found an interesting article comparing these two steels. https://www.makeitfrom.com/compare/...ss-Steel/SAE-AISI-52100-G52986-Chromium-Steel

They look almost identical. Also read another study by a nuclear engineer comparing them in a humid, co2 pressurized atmosphere where the 440c outperformed 52100 by a factor of two.

Specifically I’m looking at replacing the bearing in my Velocity A23 wheel set. Trying to decide on the best balance between price performance and longevity. Mainly price and longevity as I would suspect any quality unit would perform well. Maybe a slight slight slight deference between -RS and -LLB designs (rubber seal vs double light labyrinth).

Front: 609 (x2)
Rear: 6001 (x3), 6901 (x1)

 

[MRC01]

... Specifically I’m looking at replacing the bearing in my Velocity A23 wheel set. Trying to decide on the best balance between price performance and longevity. Mainly price and longevity as I would suspect any quality unit would perform well. ...

Those are standard sizes and any quality bearing, for example an NSK or SKF, will do the job well. IME, longevity is determined mainly by how the bearing is used and serviced. Except for impact/abuse, bearings die when they go dry or get contaminated. Especially on mountain bikes. Pop off the bearing seals, clean it out and fill about 2/3 full with a high quality #1 or #2 grease. I do this when they're new, and when I suspect it may have been contaminated (ridden in muddy/dusty/rainy conditions). The bearings in my tandem have 20,000 miles and still spin like new.

 

[853okg]

Those are standard sizes and any quality bearing, for example an NSK or SKF, will do the job well. IME, longevity is determined mainly by how the bearing is used and serviced. Except for impact/abuse, bearings die when they go dry or get contaminated. Especially on mountain bikes. Pop off the bearing seals, clean it out and fill about 2/3 full with a high quality #1 or #2 grease. I do this when they're new, and when I suspect it may have been contaminated (ridden in muddy/dusty/rainy conditions). The bearings in my tandem have 20,000 miles and still spin like new.

I agree, far more important is the quality of the bearing, and you can’t go wrong with SKF, for example. I remember when Bullseye pulleys stopped using high quality German made bearings and substituted inexpensive substitutes. They looked identical but failed before long.