Sorry, looks like I did not do a good job at bringing my points across. I did not want to push you to defend bike manufacturers or press-fit BBs. I also don’t think it is bad intentions from the manufacturers.
What I wanted to say was given the prices customers should hold manufacturers accountable, and that currently a lot of BB problems seem to be due to manufacturing not sticking to tolerances. Any BB standard is only as good as its execution, which includes T47. PF can work just fine, I don’t have a glowing hatred for them.
I would be careful assuming companies with in house manufacturing are automatically doing better. Good manufacturing control has far more to do with understanding the product and process than where it’s done.
Of course. But at the very least, I can call them and yell at them directly if there is a problem. Plus, small builders live and die by reputation. Much easier to check than with the big companies.
Thats not to say big companies and bike brands are bad. But if you go the hand built rout, there are lots of options that aren’t available.
Biggest one that I am aware of is difficulty working with 30mm cranks.
Additionally, there can be benefits to the larger overall size, specifically bearing size, to improve feel and longevity of larger bearing balls within them.
BSA threads are too narrow to fit the bearings inside the threading while T47 seems to be big enough to allow inboard bearings. This would allow the frame to be wider between the cranks by almost 20mm which means the frame can be stiffer.
(Though can use outboard bearings the same as BSA)
This problem was highlighted on the Cyclingtips nerd alert podcast a while back - a high end mechanic in Boulder commented that this was a common problem, even on high end bikes. Between this and sometimes clearly visible on camera tolerance issues on BBs on Hambini’s channel there does seem to be a lack of care regarding tolerances in the bike industry.
From seeing a few £3000+ 2021 bikes from 2 big brands up close I would go further. There is a lack of care full stop and an expectation people will buy expensive bikes no matter the quality. One looked to have poor forming of tubes (especially headtubes) with inconsistent assymetrical shapes across bikes of the same and different sizes. Another with translucent paint showed carbon joins (typical) but also what looked like sections where the resin had not properly impregnated the carbon.
Hambini just had an “Open Up” with horrible BB tolerances - that’s a $3000 frame and they can’t be bothered to get it right.
Threaded BBs don’t solve all the problems, but I think gross tolerance errors will be harder to hide.
That’s cool but it doesn’t make sense to face the top of the head tube. The bearing is sitting inside a carbon seat. Facing the top edge does nothing to help that bearing. Otherwise, cool article/video!
I noticed that as well - as opposed to facing a metal head tube where the bearing cups press in, and squaring the headtube would make sense. That said one of the pictures showed a cutter with what looked like a profile for cutting the angled bearing seat for a head tube, so he may be actually facing the entire bearing seat.
I would still prefer to have metal bearing seats, but that seems out of style since it adds a few grams. This is one of those cases where trickle down from the pros is bad - they don’t care about the longevity of the frames - as long as they last about 1 season that is long enough. I expect a much longer lifespan from mine
Facing the top of the head tube is important - worst case the conical spacer binds up and the steerer can’t turn, and it can result in play from he reducer not being pushed in. This can be either, or both, the top bearing cup being machined too deeply or the top of the headtube being out of square (absolutely, versus the bearing cup, or top not being finished straight).
I love BSA and all my bikes including MTB are BSA, I only want threaded. That being said, BSA combined with Di2 seriously limits your crankset options (only 24mm spindle) and this starts to be a problem for me. So I am seriously looking at T47 for n+1.
Our other BB expert Luescher Teknik had a video on BB standards recently, and his opinion of T47 is quite negative: technologically it is inferior to pressfit BBs, and it is an admission by bike manufacturers that they can’t manufacture BBs to spec. According to him (and that makes sense to me) the best solution would be to press the bearings directly into the frame — which is done in many other contexts.
I’m not so sure. It could just complicate everything even further and you exchange one set of problems with a new one. Most worryingly the manufacturers who have adopted T47 are basically admitting they are not even going to try to Build their frames to spec. What makes you think they’ll be more stringent with the threads and all the additional parts? Plus, you will still need to press bearings — into cups this time. So if you have a problem with T47, and the bike manufacturers are still playing fast and loose with tolerances, diagnosing BB issues a is probably going to become more difficult.
The failure mode is better. If pf had issues cause the frame isn’t to spec that is hard to prove. If the metal to carbon bonding failed in t47 that is easy to prove and get warrantied
