Is it? Outright BB failure is IMHO rare. Even an egregiously misshaped PF BB isn’t failing in the sense that it is dangerous to ride. It’ll just eat bearings for breakfast. And what is the analog of a metal-to-carbon bonding failure on a press-fit BB?
Unless manufacturers get to grips with their tolerances, BB problems will persist. If you are a customer and you are plagued by BB problems on a bike with a T47 BB, it is much harder to diagnose. And once you replace one of the parts the frame manufacturer can shift the blame to the manufacturer of the other parts, the bike shop or you. Perhaps from the vantage point of bike manufacturers the other “solution” is to make BB replacements cheap. An Ultegra BB costs me about $35 in my bike shop (I live in Japan, so prices may vary), which is quite cheap all things considered.
In over 10 years in the bike industry, I can’t think of a single bike that I saw warrantied for BB shell problems. But that was also pre-PressFit.
I personally have had two PF BB’s on which I could not resolve creaking BB’s, including one that was warrantied.
It is also worth noting that everyone keeps criticizing the bike manufacturers for tolerance issues. But there are two components in play…the frame and the BB. It is entirely possible that there are minute variances in tolerance that individually would not be an issue, but the two combined creates problems. IOW, it may not solely be the frame’s fault exclusively.
PF is a classic example of something that sounded good in concept, but in execution was not possible.
What about custom frames (steel/titanium) which potentially have better tolerances with the correct builder? Would it make sense to go for PF BB rather than the commonly spec T47 BB?
Have a look at other industries, tolerances are a solved problem, we have learnt how to produce things in very large volume to exacting tolerances. My Macs, iPads and iPhones have all been produced to exquisite tolerances, and they make many, many more of them.
Press-fit bearings are ubiquitous, they are not some novel, weird concept the bike industry came up with. Indeed, it is the best solution as it minimizes the number of parts and avoids extra manufacturing steps.
Issues with tolerances are not new or unique to carbon frames. The seat tube of my mountain bike (with aluminum frame) is slightly too large, which means my seat post easily slips unless I apply ungodly force with the QR clamp. If manufacturers don’t improve their game when it comes to tolerances with the BB, you can expect problems to crop up in other areas as well.
Have a listen here and here, this is pretty neatly explained by someone who knows more about engineering than I do. But in summary, you have less parts, less manufacturing steps and this is how cartridge bearings are used in most other applications.
Just to be clear: I’m not a PF fanboy, I actually don’t care whether my cranks are held in by pixie dust sprinkled onto the frame. I care about stuff being made right, especially expensive stuff. T47 only sidesteps the issue and does not address other issues that come with manufacturing tolerances (e. g. slipping seatposts). That’s why I dislike T47, it is an admission by bike manufacturers that they can’t build to spec.
For a custom frame, it seems that a T47 shell is required if I want to route the brake hose internally , BSA shell wouldn’t have enough spacing for example.
I haven’t heard about PF being used for custom frames, I assumed that is because of the “bad reputation” of PF that nobody wants to use it when they can actually specify the BB standard that they prefer on their custom frame.
Either way, I have no real preference for a BB system, my only concern for T47 is that for a custom steel frame, the BB shell is relatively heavy compared to a BSA, but I guess weight isn’t really a concern when you are already working with a fairly heavy material like steel or titanium.
Another thing is that T47 is a relatively obscure BB standard, just a bit worried that it will no longer exist a few years down the road and parts would be hard to source.
You are catastrophizing. Manufacturers knew how to make BSA bottom brackets correctly. They couldn’t make PF bottom brackets good enough out of carbon. Some bikes do have great PF bottoms brackets - like Colnago’s solution.
The difference here is that these T47 bottom brackets will be made out of ALUMINUM. They know how to machine that precisely.
I’ve owned maybe 10-12 frames with threaded bottom bracket shells. I’ve never had a single problem that wasn’t quickly cured by removing, cleaning and reinstalling. And “problems” have been mostly non-existent over the years.
You are projecting that there will be all these problems with the new crop of threaded BBs. I don’t see it.
AFAICT, people don’t seem to have problems with steel/ti frames and press fit. Tolerances are more precise. You can hammer out an old PF bottom bracket and install a new one without damaging the bottom bracket shell.
I’ve looked at some Ti frames where T47 is an option and the biggest issue is the upcharge (usually $200-300). I’d be torn between getting an easy to service T47 BB and saving $300.
The other side of the press fit debacle is the shops and consumers. Bicycle shops without high technical skills failed at installing BBs correctly like maybe they used grease instead of retaining compound for installation. Or maybe they didn’t face the bottom bracket before pressing in cups such that cups never sat straight.
Manufacturers also didn’t help the situation. They sometimes gave incorrect or conflicting installation directions. Some said to do it dry. Some said to use grease. Some indicated retaining compound. Sometimes the bottom bracket maker’s directions conflicted with the frame makers. I think in the end, they found that only retaining compound was a sure thing.
I don’t think I am. Lackluster manufacturing tolerances do not merely manifest themselves in BB problems. Slipping seatposts, misaligned direct mount disc brake mounts, etc.
Also, Look seems to make a good job at manufacturing its frames properly.
Which is the same material that my full-suspension mountain bike’s frame is made of, the one with the slipping seat post.
Snark aside, yes, the cups can be manufactured to high tolerances when done right. But that the manufacturers will actually do that is something we should not take for granted. Just have a look at Hanbini’s complaints about the lackluster manufacturing tolerances of SRAM cranks (and the relevant parts are all metal). Perhaps it is easier, but it isn’t a foregone conclusion that the manufacturers will actually do that.
Moreover, the extra layer of abstraction not only introduces additional cost during the manufacturing process and for the consumer (as you have mentioned yourself), but you’d still be relying on frame manufacturing tolerances. Your bearings would still have to be pressed into something … a cup, not the frame, yes. Are the threads (in the frame) properly aligned? Are they round? Is the carbon-metal interface properly manufactured? What if the T47 cups aren’t perfectly manufactured?
To me that’s a clear indication that T47 is a crutch.
I think they charge extra because the extra machining time/cost/tooling in titanium is not trivial. Plus a PF BB is generally not an issue on a something like a Litespeed.
I’m aware if the claims abiut the benefits of a PF BB…what I am trying to get to is that those supposed gains (lighter, stiffer axle) are really insignificant. The overwhelmingly majority of us can’t generate enough wattage to notice (or even cause) and additional flex in a larger diameter axle. And it has been proven time and time again hiw little weight matters in performance.
And just because pressfit is used in other applications does not mean that it is correct for this application.
Again…good in theory, but the evidence is pretty clear that, compared to a threaded BB, you have a much higher rate of problems.
We can point fingers at who is to blame all day long, but it won’t change the fact that the market demand is for a return to threaded BB.
Nope, they changed the seat post free of charge, and I still need to overtighten my seatpost clamp. The second one is slightly better, to stop the first one from slipping even at ridiculous clamping force, I had to slather it with carbon grip paste.
Well, perhaps they gave me two undersized aluminum seatposts, that’s a possiblity, too, I guess
The T47 BB introduces additional manufacturing steps, which at the very least make frames more expensive. And heavier, although if you go for a Ti frame, that’s probably not your first concern.
I was solely comparing the two in terms of manufacturing and cost: less parts generally means less manufacturing steps, less complications and cheaper. Your example of Ti frames with T47 BB being more expensive seems to bear that out.
I think it is difficult to compare frames across different eras. Modern carbon frames have become incredibly light and I reckon that making the frame heavier would help alleviate some of the tolerance issues. Plus, none of us have numbers, although I’d like some.
Edit: Just to be clear, I don’t claim that you are wrong, you could very well be right.
I wonder if the up charge is due to the increased in cost in material as a T47 BB shell would be bigger as compared to a BSA shell or perhaps it is a combination of material cost plus additional machining? That said, I can’t see why there would be additional machining for a steel/ti frame?
It not the material. The Ti shell itself isn’t going to cost more than a PF Ti shell.
It’s threading that shell that takes time and money. When T47 came out taps for threading were very expensive. Even now, left and right Park Tool taps are $700.
Titanium is very hard so they may even need higher quality taps than Park sells. And those taps are also going to wear out tapping titanium over and over so there is a replacement schedule.
Not necessarily…depending on the materials, construction technique, tolerances, etc. fewer parts can often mean MORE manufacturing costs and complications. That would seem to be the case in PF BB’s.
(Also, the Ti frame example was not mine. I am ot familiar with the builder / cost so can’t really say for sure, but it seems reasonable that threaded Ti is a more expensive process)
Well, I kinda do have some numbers. Again, in 10 years working in the bike biz (pre-PF), I can’t think of a single frame I saw warrantied for creaking BB issues. I can think of a few that that had issues with galvanic corrosion, but no manufacturing process is 100% defect free.
Are those numbers anecdotal? yes and no. I worked for the second largest (IBD) bike supplier adn then the largest bike supplier in the business. So while the numbers are not necessarily “scientific” they cover a pretty wide set of data.
Well, we don’t know how well T47 actually fares, we will need to wait a few years, I guess. So I’d be cautious to say that moving to T47 BBs will solve BB problems or improve the situation. As I said, I am very skeptical since the bike manufacturers do not want to solve the underlying problem, not sticking to tolerances, but sidestep it. Plus, top-end frames seem to get more expensive each year.
You could also look at it this way: rather than improving the implementation of a concept that is known to work, manufacturers opted to introduce another standard, where they will have to start from scratch.
Thanks for giving some context, and I did not want to suggest that I want to quibble about numbers in my earlier post. I did and do own bikes with threaded BBs, in my experience (as an end user) they seem to work as well as PF BBs. Although all frames with threaded BBs are/were metal frames, and the move to PF BBs was inherently connected to carbon frames becoming mainstream.
I’ll toss in my own limited personal experience… There are a fair number of people riding Trek Domane in our club (partly because of once a year deal), and I’ve got a 2015 gen1. Never had a problem myself, however I have asked two shops about it and they say its pretty rare but does happen.
This discussion has been interesting as as my bike has taken some abuse over 5 years, and I’d like to run 28 or 32 tires on a daily bases, be able to put even wider tires for some Central Coast hard pack / gravel routes, and get the front isospeed as the gen1 front-end is a little harsh. I’m going to support my LBS which means another Domane is in my future and Trek has gone all-in on T47 for Domane. My takeaway from this discussion might sound dumb but if I get a lemon frame/BB then I’m better off buying the low-end SL 5 model and spending money on a nice set of wheels. I’d lose my mind spending $6-7k on the SLR 6 and just my luck to have creaking issues.
Agreed…which was one of my original points re: PF. It seemed good at the beginning, but it wasn’t until there was enough product out in the field over a sustained period of time that suppliers came to realize there was a problem.
Very often problems only materialize in the long term. Short-term testing (both lab and field) doesn’t always reveal a problem.
exactly, which is why if it becomes an issue I’d want to flip the bike in a year or two. Or feel good about taking advantage of a screaming deal on a used bike or frame. Thanks for helping me decide between buying low-end (plus an upgrade or two) or mid-range.
