Bottom bracket upgrade
 

Are there any benefits to upgrading a BB to a better quality one? I am honestly not looking go ceramic bearings because I've read in plenty of posts and forums where people explain that it isn't worth the cost. How about a higher quality steel bearing BB though? More specifically a Chris king BB. I have the opportunity to get a Chris King BB for $120 for my new Gen 4 supersix evo with 105 components. At that price is it a no brainer? What are the benefits?

Thanks in advance for your input.

...my own opinion, and it is only my own opinion, is that while there might be some extended lifespan in BB sealed units like the ones from Phil Wood, the more moderately priced ones, (even including the ones that are not bottom of the line from Shimano, but their slightly better offerings like the UN-55), go for so long that I am unable to wear them out. There are some deals on outdated square taper ones from Campagnolo, that you can find online, and the VO offerings are good quality, at about 50 bucks (more or less).

There's a practical limit to quality on these, because few manufacturers make their own bearings.

I know nothing about Chris King products, either headsets or BB's. The headsets seem a little pricey to me, for what you get. And you need a special extra tool to install them. Again, only my own opinion. Someone else will probably weigh in shortly.

I read all these posts on ceramic BBs in many forums. I replaced my bb with Ceramic coated BBinfinite, the improvement is huge.
after 1000 km and is smooth as the first day.

Thanks for your input! I am certainly not worried about wearing them out but I guess I just want to know if there are performance benefits to it. I don't race or anything but I like long distance rides. I am currently slowly coming back from an injury with a lot of physical therapy work. If swapping out a bottom bracket will help in any way be more efficient than I will go with it

Could you explain what improvements you've felt? Thanks!

speed increased at same watts (during the first ride at my usual segments, achieved over 100 personal records on Strava), super smooth pedaling, great feeling, would never go back. My bike has ITA bb so replacement was very easy and swift.

Benefits like that would definitely be worth an upgrade! Thanks for your input. I appreciate everyone that takes the time to share their experiences!

I am one who sees BBs as simply a tool for the job. Yes, better tools often last longer and may require less maintenance. Provide marginally better friction loss or maybe a shade stiffer. But usually, I am looking at the details of what it does. Now I have knees that love my feet being close together (low Q-factor). So much so that they announced to me they were going into retirement early if I ignored that request. (Ie, I'd have to get knee replacements to continue riding.)

So, for me, there is strong incentive to use BBs that are both as narrow as possible and fit cranksets with arms as straight as possible. So, I first find that crankset, then obtain the BB that fits it and is narrow. If I cannot find that, I will buy a Phil Wood BB, either stock or custom, that fills the bill. Expensive, yes, but my knees love the setup and I get to keep riding those cheap OEMs (knees). If my knees weren't so fussy, the $30 Shimanos would do the job just as well.

That is very useful information. I have considered slightly shorter cranks because I am going through physical therapy and I have read and watched many videos of the benefits of shorter cranks for people with my current issues. But that's a different topic.

...steel bearings and the bearing race surfaces are highly polished. It would be difficult to measure much difference in efficiency between any two particular BB units, if both are working well. The best ones are probably less efficient, because the seals on them to exclude dirt and water can drag just a tiny bit.

It's too bad you don't have access to a big old box of sealed unit BB's. You could spin them and see what I mean. There are a lot of places you can lose efficiency in a cycling machine. The BB is not one of them, so long as the bearings and races are in good shape, and the lubricating grease is not too thick (you can't control that, it comes with the unit you buy, already built into the sealed bearings).

I noticed a significant improvement in smoothness, in going to external bearings (with a hollowtech II style crank, and this was bargain-basement brand-x parts), because the bearings are larger so have more balls, possibly also bigger balls, and that makes them roll smooth. It's also a huge benefit to be able to adjust the preload to take out slack perhaps every six months, that makes a big difference in the bearings lasting longer.

I've gotten away from cartridge BBs, for the above, and because I put on a lot of miles, and it would only take a year of dry biking to start to get a tiny bit of slack in the bearings, and no way to adjust out. But if you were going premium on an internal cartridge, in addition to the renowned Phil Wood ones, SKF makes internal cartridges with their own bearings, and the crank side has roller bearings, $170 last I looked; They also say the spindle is stainless steel, excellent for seal life as no rust, but this meets specs for city and touring bikes but not racing, as the stainless can be brittle for the hardest hammering riders, they recommend someone else for racing (a surprise, as stainless alloys have advanced a lot, though most are powder-metallurgy process, which is super expensive). SKFs are 10 year warranty, but not rebuildable. If Phil Wood ones can be rebuilt at low cost by just replacing standard cartridge ball bearings, that would be a plus, but I don't know.

Don’t fall for the hype. Performance gains are extremely marginal here. But it is worth having a quality steel bearing BB and Chris King is quality. The real benefits are longevity (better seals) and quiet, smooth running (better tolerances). But the standard BB will likely be fine too.

Another benefit of a higher quality BB is serviceability. Often you can either clean and regrease the bearings or replace them with matching or sometimes higher quality bearings. Buying high quality bearings is easy.
I generally used Dura Ace BB on my Aethos. My complaint is the bearings are not serviceable at all and the bearings do not move as freely as other BB's I've installed in customer's bikes. But it is a relatively inexpensive BB.
I recently switched to a Hope BB and it is a night and day difference. It spins so much more freely and smoothly and is completely serviceable plus I can get the bearings either through a shop source or any business that sells bearings.

A couple of things worth noting here. Firstly the difference you are feeling when spinning them is mostly the seals and grease and that is often a trade-off between free-spinning and weather protection. Secondly, the actual difference in power absorbed is likely to be much less than 1 Watt between them. While I can easily feel differences in resistance of BBs when spinning them slowly by hand without a chain, I certainly can’t tell any difference while riding them, or even turning them over with the chain on.

Better tires will do more for your bike than a better BB. Strava hands out awards to everyone. So don't put much up toward that without numbers.

My cycling improves all through the season, so reports of better numbers after installing them without having done some controlled studies is suspect.

However if you do competitions, the marginal gains can mean the difference. But it's not going to help you much for just a group ride or riding solo. IMO.

Chasing performance with a BB upgrade is futile. As long as it isn’t crunching and creaking then all is good. I just use standard Shimano/SRAM BBs and they are fine and easy to replace.

The more I read and the more research I gather, the more I realize that longevity is what you really get with better quality steel bearings and not performance gains really. Thank you for the info!

I am slowly building a Surly DT, decided to use hybrid ceramic BB (with one ceramic bearing), https://www.somafabshop.com/shop/ird...=967#attr=2680
Not as expensive as a full ceramic BB, they also have sales from time to time.

My motivation for it was longevity and resistance to mud. It is probably a nice thing to have (if it works), OTOH I do not think a regular BB will catastrophically fail (lock up) in a instant. I expect it to creak and grind for a while before it completely fails.

Agree with what the others say about performance. The diameter of the BB is small. BB-MT800 or BB-R60 are less than 4cm in diameter - the radius of the cartridge with the bearings is less than 2 cm. For a 90 rpm cadence the angular speed is 90/60 * 2 * pi = 10 s^{-1}. Then for every kgf (10N) of drag in the bearings the torque is 10 * 0.02 = 0.2 N*m. The power is 0.2 * 10 = 2W.
And in the reality the drag is probably much lower, then the power loss in the BB is less than 1W.

Wow thanks for the amazing information! I very much appreciate everyone that takes the time to respond. I have noticed more and more that the difference for a more expensive BB seems to be longevity and not much if anything at all in the way of performance to gain. Since my bike is only a few months old and I don't ride in the rain, it probably doesn't make much sense to spend on a BB for now.

​​​

When a $18 BB lasts upwards of 20,000 miles or more, why would you need to pay for more longevity?

Um, my standard Shimano bottom bracket has to be way less than 1w of drag. My pedals have as much drag as the bottom bracket.

I happened to have the chain off today, so I did a quick check. These bearings have been in there for a few years already. Just a very light pressure with one finger is enough to turn the crankset. A 20 gram AA battery set onto the pedal end of the crank is also enough to turn it. A fast spin goes three or four revolutions -- actually, I expected to see 6-10 revolutions, but even this amount of drag isn't a factor when riding.

If you had the extra watts from "very light pressure with one finger" added to your riding pedal stroke, it wouldn't be measurable.

Yeah, forget about it until it starts making noises.

Keep in mind that unloaded performance is not a good predictor of loaded performance.

If any quality BB was not still smooth as glass with 600 miles on it, I would be SO pi$$ed at the poor quality. The last BB bearing I had to replace was after about 80,000 miles and I have had them last longer than that. Ceramics offer zero performance benefit at a significant price penalty.

Do people even measure the bottom bracket drag at all and how do they do it?
Hanging equal weights on the two pedals (say 100-150# each) is not a model of a real load.
The real load is asymmetric, which will probably increase the drag.