So I've hated the press fit bottom bracket standard ever since it came out. I think it's utter sh1te.
To the point where I would not consider a frame unless it was good old threaded. Threaded to me is far superior.
I know the manufacturers bang on about bigger contact area to join to and all that b0llocks but there are a lot of high end frames still using threaded and they don't have a problem.
Press fit was basically a standard that was not needed. Luckily I don't and won't own a press sh1t bb/frame. Really can't see any advantage.
This all started because a mate asked me to look at his poorly bike. Upon inspection the BB is snagged. It's a nylon cup sram jobbie that must have cost a few pence to produce and sram want an eye watering £36 for one!
Where is the progression? My shimano threaded BB has lasted me ages, it has metal cups which I can take out with ease without having new and expensive tools. I think the BB was £15.
It's made me realise how much better a threaded BB shell is but it also got me thinking.
Why have we never had threaded headtubes and screw in head set cups. I think they sound be great.
I'd never really thought about it until I felt a press fit BB was a step back. Now over the years I've had about 4 frames warranties die to loose headset cups, starts off with a creak under hard braking and before you know it they were creaking like crazy which is the same thing everyone complains about with press fit bb's... bl00dy creaks!
So has any manufacturer ever done a threaded headtube? There must be a reason why they don't do them and surely it can't just be a cost only thing.
Do you want a hug?
A threaded headset could potentially come undone as the bars regularly turn in both directions unlike a crank which primarily turns in the same direction that a bottom bracket cup tightens. Hence why we have a reverse thread on one bb cup.
POSTED 1 HOUR AGO #
Rorschach - Member
Do you want a hug?
Erm no thanks.
andysredmini - Member
A threaded headset could potentially come undone..
I agree, but couldn't there be some sort of retaining pin/clip to avoid this?
Um, a crank primarily turns in the direction that bb cups undo!
In that case....
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Yes. If they screwed in the other way they'd tend to undo themselves. Precession, innit, and it's the same reason pedals screw in the opposite way to their respective side's BB bearing.
Here, I googled it for you-
https://en.wikipedia.org/wiki/Precession_(mechanical)#Bicycle_bottom_brackets
blimey, [i]somebody[/i] on here sure needs a hug 🙁
😆
Threaded headset?
Why?
Press fit works fine.
Only BB failure i've ever had was a threaded one. I have 4 bikes with PF BB's and all have been fine 2 of them have nearly 2 thousand miles on them.
Different applications, headset is essentially a thrust bearing arrangement, BB is a shaft supporting setup, although both see a fair bit of wonky loading. Personally I haven't ever suffered a creaking or flared head tube, but I might just be lucky.
TBH a threaded head tube could work the reason for it not being done historically was probably the additional cost, and you would have needed a relatively a large dia tube and thread to accommodate a sensible lower bearing and allow the steerer to pass through.
Of course now things like backwards compatibility and sensible pricing are no longer en-vogue in the bicycle industry so I would get the patent in before specialized do OP...
Cost, cost, cost, cost and cost. With carbon moulding and alu hydro forming manufacturers could easily produce dirty great BB shells with threaded elements for the cups to be screwed into. Press fit is one process less in the frame manufacture as no threads need to be cut and it reduces assembly time as you don't gave to screw in a BB. That's what my cynical mind thinks anyway.
Probably also a historic element.
Bb shells (used) to only be one or two lengths,often bought ready threaded and then brazed into the frame.
Head tubes can be a huge number of lengths, so harder to make a stock of different threaded lengths. Would also need to be thicker (heavier) to accommodate the thread.
Head tubes can also distort (ovalise, flare or bend) more due to weld/braze heat of two big tubes on one side only. Press in cups probably more tolerant of this or easier to rectify.
Pressfit is 2-3 less process's in frame manufacture, 100-150g less weight, and a cost saving into the bargain.
I'll only ever use PF again with one of those Praxis Collet type BB's. I hate them.
PF BB shells allow a larger weld area, hence slightly improve overall frame strength to weight ratio.
Sure, I've had to bin a couple of PF92 BBs (XT and some cheap SRAM item) but in the same timescales, the bearings on threaded XTR and RaceFace DH Team BBs also failed on a different bike (Cove frame with faced BB shell).
If you're worried about bearing alignment, I recommend a Hope PF41 (if you can afford it). It'll solve your problems, and the bearings will outlast most PF BBs on the market.
Don't be too put off, PF isn't all that bad 😉
ic-al - Member
Threaded headset?Why?
Press fit works fine
I've had 3 frames warrantied over the years due to bad tolerances and sloppy headset fit.
Just think threaded would be better.
I seriously can't see it coming undone. Done up tight and with Locktite it would come undone.
Anyone ever had there threaded BB come undone from back pedalling?
I've got a bit currently where the headset cups latterly pushed in by hand.
mick_r - Member
Probably also a historic element.Head tubes can be a huge number of lengths, so harder to make a stock of different threaded lengths. Would also need to be thicker (heavier) to accommodate the thread
Very good point.
I'm getting my mate to go for a hope pf46.
I'm a big hope fan boy so expecting the quality to be good compared these cheap sram nylon cup things.
I've had 3 frames warrantied over the years due to bad tolerances and sloppy headset fit.
I've worked on hundreds of bikes or more over decades, I've seen a handful of headtubes get damaged by riding them loose. Seen way more frames trashed by seized threaded BBS!
Anyone ever had there threaded BB come undone from back pedalling?
Seriously, you've lost it.
Yes. If they screwed in the other way they'd tend to undo themselves. Precession, innit, and it's the same reason pedals screw in the opposite way to their respective side's BB bearing
BB bearings unscrew in the normal crank direction. Going back to square taper style BB's if the bearings jam then the BB unscrews out of the frame. On HT2 style they will unscrew and jam against the cranks. If they tightened then you would risk over tightening in the frame and trashing the frame.
Pedals tighten with the normal rotation. If they unscrewed then you could have a very nasty accident resulting from a significant loss of control when your pedal falls out if you are standing out of the saddle.
Have had two frames with BB92 press fit bb's (hope pf41), no creaks and have lasted as long as any good threaded BB.
Anyone ever had there threaded BB come undone from back pedalling?
Seriously, you've lost it
Why? I've seen countless posts from people complaining the chain is dropping off the big cog at the back when they back pedal so people obviously do it whether to adjust pedals on corners or warm up at races a bit.
Are you suggesting their bottom brackets are going to come undone?
There's some weird talk here about threaded BBs coming loose while pedalling....
The only BBs I've ever seen come loose are Italian thread drive-side cups on road bikes (I'm going back a few years here) and that was mainly because they weren't left-hand thread.
Italian BBs have an annoying habit of coming unscrewed because both side are RH threaded.
On the subject of BBs, cartridge square taper ones last years - then Shimano though we'd progress by sticking them outside the shell and unleashed all manner of cr@ppy designs
My pressfit BB is perfect, even after 2k of mucky, wet trail riding 😀
Was expecting it to be a headache but it's outlasted 2 XT BB's on my other bike!
Royce square taper, fit and forget.
There's nothing wrong with pressfit BBs. They creak because the crank axle flexes within the inner races, which can be cured by smearing bearing fit compound on the two machined areas of the crankset axle which sit within the bearings.
The tapering on head tubes isn't universal so we'd end up with another five different headset standards.
Tha last thing required is another range of 'upgrades'. Also, it would come lose and then you could moan about creaking bottom brackets and headsets. My press fit is quiet so Ill keep quiet!
what I learned about press fit BBs is, if they creak..first thing is to check tolerances !!
some BB shells are not exactly round due to the welding ..and while manufacturer save every penny they does not check or correct that..
the shimano PF BB with its plastic bearing shells helps to hide that fault for a while...but to solve the problem the only way is to
mill/ream the shell with a tool like this..
http://www.2soulscycles.com/index.php/store/product/1043-bb92-reamer
for me thats the reason why some are very happy with their PF BBs
and others buy one BB after another and have always problems with it
andyl- did you read and [i]understand[/i] the context of my post, or did you just shoot from the hip? 😆
I was answering jabbi's post, the next-but-one above my orginal post in this thread.
Right side BSA BB threads in left-handed, right side pedal threads into the crank arm right-handed. Left side is the opposite. Mechanical precession. Google it, learn something and try reading before you type.
I'm not a fan of press fit bb's either. I wont buy a frame with a press fit bb shell..
I've done 3685.5 miles on my carbon framed Rocky Mountain, in some utterly filthy conditions, through 4 Norwegian winters and one back in the UK. I've changed the press-fit bb bearings once. Outlived any other I've had.
My Supersix road bike with carbon pf bb has done 5183.7 miles with no bearing change...
Guess I was just lucky and/or ride like a fairy.
kayla1 - Member
andyl- did you read and understand the context of my post, or did you just shoot from the hip?I was answering jabbi's post, the next-but-one above my orginal post in this thread.
Right side BSA BB threads in left-handed, right side pedal threads into the crank arm right-handed. Left side is the opposite. Mechanical precession. Google it, learn something and try reading before you type.
kayla1 did you get out of bed the wrong side this morning?
The posts [b]above[/b] yours seemed to be confused with which way a BB actually unscrews (on purpose, with the tool). Your post was lacking detail and clarity on which way they are actually turned to install and remove which is what I was adding along with the case of when a bearing seizes.
Your posts seem very angry and you seem to have a short temper. Maybe the STW isn't for you? You might give yourself a heart attack with the stress and that would seem to be a bit of a shame... 🙄
Are you suggesting their bottom brackets are going to come undone?
Ah ha! No, just pointing out how ridiculous an idea that is
Actually took longer than expected before this thread went South! Lol
I just don't want another standard!
Seriously, not another! 😀
Not sure what needed answering in my post. andysredmini posted that a bb tightens in the direction of rotation, I was just pointing out that it doesn't. I would have quoted him but it doesn't work on a PS4!
[url= http://www.odysseybmx.com/dailyword/2004/09/79-bottom-brackets-again/ ] BMX had this adventure over a decade ago. and no bugger seems to have learned a thing from it.[/url]
Personally I think PF BB's as implemented in recent years on MTBs and Road bikes are pretty much all toss.
The best solution would actually have been to adopt a version of the US or Mid' bottom bracket and have a couple of nice big robust bearings pressed in to a frame along with a proper support arrangement and axles to suit the applications and limit axles to 3/4" dia...
TBH Euro was fine for most mortals until the axles became silly oversized with ISIS and then HT2.
So now the shell diameters are creeping up (along with the axles), of course aluminium and Carbon frame weights aren't so much of an issue, just bearing mass, but then if you want a bearing with a good load rating, it's going to weigh more and you are going to have to support it properly.
they make it easier to manufacture bikes on a large scale.
this is the main reason they use them.
BB and pedals are threaded to tighten when riding. It certainly looks like they will unscrew during riding when fitting them, but the balls of the bearing reverse the forces so they now tighten.
That's why a jammed bearing will unscrew if they threads aren't too tight
A proper, threaded BB is one of the things that swayed me towards my Kona.
I just can't persuade my head that press fit is a good engineering solution, even though I have no engineering training, and people who do say it is fine.
It can't be right, can it?
(See also Lefty forks. They can't be right, either.) << edit: oh, accidental pun. I hate puns.
If you want to prove the threaded BB tightening thing deliberately and scientifically, you can take a bike with an EBB, install the insert the wrong way round in the frame, and thread the BB in so that's backwards in the frame too.
Both cups will start working themselves out of the insert as you pedal. Hey presto/ QED.
Or you can do it by accident. 😳
Your posts seem very angry and you seem to have a short temper. Maybe the STW isn't for you?
😆
😆 I had had a really crappy morning yesterday, and probably too much coffee. Sorry for being a cow!
edit- genuine apology, by the way.
Dorset_Knob - (See also Lefty forks. They can't be right, either.)
Works for cars, aircraft...etc can't be all wrong.
sq225917 - Praxis Collet type BB's.
Been looking at those as I'm not 100% convinced on press fit though my Cannondale has given me no reason to complain, not sure they will work with my cranks though, don't really want to spend out on cranks if I don't need to...
Cheers, Steve
press fit isn't the problem per se. It's bad implementations and shoddy tolerances.
I got a bb infinite one and it's perfect. Well worth importing from the states. No creaks!