# Ball bearing quality



## Minjin (Dec 31, 2006)

Not sure what forum this should be in. We'll start here I guess...

I have some cheapie pedals (stock pedals from a Redline Monocog) that were getting grindy and starting to seize. I'm too cheap to replace them so I decided to just change out the bearings, one of which was completely crushed and looked more like a pancake. I measured them to about 4mm which means that they are probably the common 5/32" size. When I went to order some on ebay, I got stuck at the decision on quality. Bearings are measured in grades that sort them by sphericity and surface finish. Lower G number means better grade. I did some quick google searching and people seemed to suggest that high end bicycle components use G25 and that that is the recommended grade. Fast forward to today and I got my G25s and I'm comparing them side by side with one of the good old bearings using a loupe. Frankly, the new ones don't look as good. They appear to have a much rougher finish, which confuses me because I can't imagine that these cheap pedals came with awesome bearings.

So, should I have ordered G10 or lower instead of the G25? What grade do you guys normally use? Do bearings in use get more polished as they are used? Could that explain it?

edit: Oh, and yes I bought chrome steel bearings not carbon steel.
edit2: because everyone likes pictures


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## mtnbiker72 (Jan 22, 2007)

First off...there is no way you can visually tell the difference between a Grade 300 and a Grade 25 bearing without some serious magnification.

Secondly, your bearings are only half the equation, the races are the other. If they aren't polished to the same grade as the bearings then it isn't going to make much difference. For cheap hubs, pedals, headsets, etc that use open ball bearings...Grade 25 is well above the level of polish on the races, frankly Grade 300 is usually above the polish of the races.


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## whitfield96 (Mar 18, 2011)

Similar question ~ Bearing quality. 

I can buy 6802-rs bearing for my rear suspension ~ prices range from $3.66 - $76.95 (Per Bearing)

I want to buy quality but how much do I really need?


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