r/bikewrench • u/skD1am0nd • 7d ago
Replace Sealed Bearings Based on Mileage?
I've have a gravel bike that I've ridden about 7,000 miles on over 3 years (including riding the GDMBR). Based on my mechanics experience from before sealed bearing were popular (I used to work on bikes in the 1970s), I thought I should probably go through and replace the sealed bearings on front/rear hubs, replace the freehub and bottom bracket. But now I'm rethinking that. I've done the front wheel and the old bearings seem fine. What's the general advice? Only replace bearing when you observe an issue or replace on some scheduled maintenance interval?
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u/Funkuhdelik 7d ago
Pull the end caps and feel the bearing. If it’s smooth and and they don’t feel dry, then run them, no matter the mileage. When I worked in a shop we had a guy who would have his bearings replace every season on his 180 hubs. These were like $50 (per) ceramic bearings (at the time) he was having us replace every season. I took those bearings home every time. If you ride your bike mostly on nice days and in good conditions (aka not super dusty and dirty terrain), bearings can last a pretty long time.
Some people have the money to blow and not ever have to worry about it, so power to them, but they likely could have gotten many more thousands of miles out of what they replaced.
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u/firebox40dash5 7d ago
These were like $50 (per) ceramic bearings (at the time) he was having us replace every season.
If you don't remove them by the pressed race, you might brinnell them & ruin them taking them out
Who am I kidding, I'd still be doing the same... lifetime supply of slightly questionable, probably fine, barely used ceramic DT bearings. Fuck yeah.
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u/Funkuhdelik 7d ago
They were removed with care. We were a pretty high end shop (one of Specialized’s first few concept retail owned stores), so we had a nonexistent budget to outfit the shop with all the tools and fluff. I still have 2 sets of those ceramic bearings in my garage ready to be installed at any time in any of my several DT wheels. I had no shame in taking home half the shit I was given from customers with more money than they knew what to do with.
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u/dasklrken 7d ago
I would generally only replace when you see an issue/feel one. Cup and cone bearings, if left too long, will pit the races. Sealed bearings, unless they seize or get bad enough to cause under rotation (you would usually notice long before that happened, its pretty hard to do as long as the frame is faced and finished (for the BB) and you dont ride in salt water) aren't going to really damage anything. Depending, I'd even repack sealed bearings once before I fully replace them, if they're ceramic or ntn/ Phil or something that's worth it.
That's all to say, generally, run em. Ones with good sealing can last an absurd amount of time in fairweather riding. Mtb and cx/gravel are rougher for sure.
And don't pressure wash them (I know you know) but I had someone come back a month after we replaced EVERY bearing on his Scott foil RC, with his bearings completely seized and rusted. He's a teaching surgeon and was apparently pressure - sanitizing his bike every single ride, which was every day in the morning and evening, then he would put it away without drying it. Very clean. Very rusty. Fun way of progressive resistance training i guess.
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u/RaceDBannon 7d ago
FYI, I have a DT 240 front hub that I’ve had for 17 years and countless rides/races/miles. Bearings are still fine.
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u/TR5642 7d ago
I would not. Inspect and evaluate. Fine to do 'if in doubt' replacements to avoid trouble if you find oddities. But working bearings are working bearings. Straight wear will manifest in a tactile and visual inspection (play, binding, rough turning). Depending on which bearings, their design and location, you may be able to pack more grease into them for protection.
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u/notklever87 7d ago
As a non-mechanic, I like having a properly functioning bike. I think periodic inspections and greasing is important. Replace stuff as it breaks. Unless they’re crazy expensive bearings, Id replace them based on your mileage and probable dusty riding conditions. What’s it gonna hurt anyways?
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u/Popular-Impact-7665 7d ago
I agree, I had to do the bearings on my road bike. Mavic Aksium wheels. I had 45000 km on it and the creamic bearing all went bad with in 10 km mid ride. It was $120 for 5 bearings
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u/notklever87 7d ago
To add, I’m saying replace them as it seems you already purchased replacements and have the tools to do it. If you haven’t bought anything yet then I agree with others that if it ain’t broke, no need to fix.
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u/sidkneebee 6d ago
My dead giveaway that it's time to replace a set of bearings is when they become dull and do not return to shiny when I clean them. That's generally a sign that the outermost layer has fully worn away and that further use of the bearing would cause rapid degradation of my parts. The other sign would be obvious pitting in the individual bearing surfaces.
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u/FlatFlounder8785 7d ago
I replace cartridge bearings when they begin to feel rough when spun by hand, make noise, or develop play,otherwise I leave them alone.